Elliptical Chainrings

[Steve Freides]

Seems more people are riding elliptical chainrings than I remember in
years past. Not a new thing but has never become a majority preference
in the TdF, either.

Comments? Everything I've ever read, including a quick Google just now,
says there is no evidence to support the idea that they're in any way
better.

-S-

[Phil H]

Post by Steve Freides
Seems more people are riding elliptical chainrings than I remember in
years past. Not a new thing but has never become a majority preference
in the TdF, either.
Comments? Everything I've ever read, including a quick Google just now,
says there is no evidence to support the idea that they're in any way

There is a resurgence of these things since the orientation (clocking) of the ellipse was found to be off. Marketing.....get a winner to ride them and sell a million.
Phil H

Post by Steve Freides
better.
-S-

[Sir Gregory Hall, Esq·]

Seems more people are riding elliptical chainrings than I remember in years
past. Not a new thing but has never become a majority preference in the
TdF, either.
Comments? Everything I've ever read, including a quick Google just now,
says there is no evidence to support the idea that they're in any way
better.

Elliptical chainrings are a GIMMICK. Why?

Because gearing depends upon the number of teeth on
the chainring and the number of teeth on the cassette.

When spinning the crankshaft it doesn't matter one iota
what shape the chainring is. All that matters is the
relationship between the number of teeth on the
chainring and the number of teeth on the particular
cassette ring.

Any idiot who thinks otherwise is just that, an idiot!

[Davey Crockett]

" Sir Gregory Hall, Esq·" a écrit profondement:

| Elliptical chainrings are a GIMMICK. Why?
| Because gearing depends upon the number of teeth on
| the chainring and the number of teeth on the cassette.
| When spinning the crankshaft it doesn't matter one iota
| what shape the chainring is. All that matters is the
| relationship between the number of teeth on the
| chainring and the number of teeth on the particular
| cassette ring.
| Any idiot who thinks otherwise is just that, an idiot!

The original concept, way back, was that the eliptical shape
allowed one to transmit the same, or reasoably the same, power to
the drive train whether the cranks were at TDC, BDC or any other
aspect.

(TDC=Top Dead Center)

Davey remembers Jeff Bernard proudly sporting the "BioPace" decal
on his regular (round) chainring. He didn't believe the Shimano BS
either apparently.

[Steve Freides]

Post by Davey Crockett

Post by Sir Gregory Hall, Esq·
Elliptical chainrings are a GIMMICK. Why?
Because gearing depends upon the number of teeth on
the chainring and the number of teeth on the cassette.
When spinning the crankshaft it doesn't matter one iota
what shape the chainring is. All that matters is the
relationship between the number of teeth on the
chainring and the number of teeth on the particular
cassette ring.
Any idiot who thinks otherwise is just that, an idiot!

The original concept, way back, was that the eliptical shape
allowed one to transmit the same, or reasoably the same, power to
the drive train whether the cranks were at TDC, BDC or any other
aspect.
(TDC=Top Dead Center)

Wouldn't it make more sense, then for the pedaling circle to be
elliptical, rather than the chainrings? I'm not quite sure how one
would achieve that end, but Sir Gregory Hall seems to have a point
here - if you're still pedaling circles, it doesn't matter how the
chainrings are shaped.

Post by Davey Crockett
Davey remembers Jeff Bernard proudly sporting the "BioPace" decal
on his regular (round) chainring. He didn't believe the Shimano BS
either apparently.

Ah, yes, I did try BioPace back in the day. NB: they, nor any other
non-round chainrings, are terribly useful on a fixed gear.

-S-

[Mower Man]

Post by Steve Freides

Post by Davey Crockett

Post by Sir Gregory Hall, Esq·
Elliptical chainrings are a GIMMICK. Why?
Because gearing depends upon the number of teeth on
the chainring and the number of teeth on the cassette.
When spinning the crankshaft it doesn't matter one iota
what shape the chainring is. All that matters is the
relationship between the number of teeth on the
chainring and the number of teeth on the particular
cassette ring.
Any idiot who thinks otherwise is just that, an idiot!

The original concept, way back, was that the eliptical shape
allowed one to transmit the same, or reasoably the same, power to
the drive train whether the cranks were at TDC, BDC or any other
aspect.
(TDC=Top Dead Center)

Wouldn't it make more sense, then for the pedaling circle to be
elliptical, rather than the chainrings? I'm not quite sure how one
would achieve that end, but Sir Gregory Hall seems to have a point
here - if you're still pedaling circles, it doesn't matter how the
chainrings are shaped.

Post by Davey Crockett
Davey remembers Jeff Bernard proudly sporting the "BioPace" decal
on his regular (round) chainring. He didn't believe the Shimano BS
either apparently.

Ah, yes, I did try BioPace back in the day. NB: they, nor any other
non-round chainrings, are terribly useful on a fixed gear.
-S-

Isn't it the point that elliptical chain rings actually vary the gear
ratio? Forget the number of teeth, they're only there 'cos a chain is
used. Think of diameter. Variable diameter. Honest. Think drive belt?
Big pulley vs small pulley?

[Steve Freides]

Post by Mower Man

Post by Steve Freides

Post by Davey Crockett

Post by Sir Gregory Hall, Esq·
Elliptical chainrings are a GIMMICK. Why?
Because gearing depends upon the number of teeth on
the chainring and the number of teeth on the cassette.
When spinning the crankshaft it doesn't matter one iota
what shape the chainring is. All that matters is the
relationship between the number of teeth on the
chainring and the number of teeth on the particular
cassette ring.
Any idiot who thinks otherwise is just that, an idiot!

The original concept, way back, was that the eliptical shape
allowed one to transmit the same, or reasoably the same, power to
the drive train whether the cranks were at TDC, BDC or any other
aspect.
(TDC=Top Dead Center)

Wouldn't it make more sense, then for the pedaling circle to be
elliptical, rather than the chainrings? I'm not quite sure how one
would achieve that end, but Sir Gregory Hall seems to have a point
here - if you're still pedaling circles, it doesn't matter how the
chainrings are shaped.

Post by Davey Crockett
Davey remembers Jeff Bernard proudly sporting the "BioPace" decal
on his regular (round) chainring. He didn't believe the Shimano BS
either apparently.

Ah, yes, I did try BioPace back in the day. NB: they, nor any other
non-round chainrings, are terribly useful on a fixed gear.
-S-

Isn't it the point that elliptical chain rings actually vary the gear
ratio? Forget the number of teeth, they're only there 'cos a chain is
used. Think of diameter. Variable diameter. Honest. Think drive belt?
Big pulley vs small pulley?

But big pulley versus small pulley, first of all, means something
different for belt drive than for one with teeth. If one pedal
revolution gets you 39 teeth spaced evenly apart, what's the difference
what the shape is? For a belt driven system, a change in shape could at
least mean a change in circumference.

-S-

[none) (Yannick Tremblay]

Post by Steve Freides

Post by Mower Man
Isn't it the point that elliptical chain rings actually vary the gear
ratio? Forget the number of teeth, they're only there 'cos a chain is
used. Think of diameter. Variable diameter. Honest. Think drive belt?
Big pulley vs small pulley?

But big pulley versus small pulley, first of all, means something
different for belt drive than for one with teeth. If one pedal
revolution gets you 39 teeth spaced evenly apart, what's the difference
what the shape is? For a belt driven system, a change in shape could at
least mean a change in circumference.

For 1 complete revolution, there is no difference. Absolutely correct.

However what about 1/4 of a revolution or 1/8 of a revolution? Then
the diameter of the "big pulley" does differs.

Yan

[Friso]

Post by none) (Yannick Tremblay

Post by Steve Freides

Post by Mower Man
Isn't it the point that elliptical chain rings actually vary the gear
ratio? Forget the number of teeth, they're only there 'cos a chain is
used. Think of diameter. Variable diameter. Honest. Think drive belt?
Big pulley vs small pulley?

But big pulley versus small pulley, first of all, means something
different for belt drive than for one with teeth. If one pedal
revolution gets you 39 teeth spaced evenly apart, what's the difference
what the shape is? For a belt driven system, a change in shape could at
least mean a change in circumference.

For 1 complete revolution, there is no difference. Absolutely correct.
However what about 1/4 of a revolution or 1/8 of a revolution? Then
the diameter of the "big pulley" does differs.

I think that's the point of Biopace and this new system (has it got a
name yet?). The strength needed to rotate 1 cycle is equal, but with an
elliptical chainring this strength is supposed to be more equally
distributed.

Given the way everything is shaking and non-smooth there must be an
effect. I would think this effect is negative, also given the silent
passing of Biopace, but given the performance of Froome that doesn't
make sense.

I wonder: is it still possible to stand up on your pedals when you're
going uphill, or is this why Froome is almost always sitting?

[Sir Gregory Hall, Esq·]

Post by Friso

Post by none) (Yannick Tremblay

Post by Steve Freides

Post by Mower Man
Isn't it the point that elliptical chain rings actually vary the gear
ratio? Forget the number of teeth, they're only there 'cos a chain is
used. Think of diameter. Variable diameter. Honest. Think drive belt?
Big pulley vs small pulley?

But big pulley versus small pulley, first of all, means something
different for belt drive than for one with teeth. If one pedal
revolution gets you 39 teeth spaced evenly apart, what's the difference
what the shape is? For a belt driven system, a change in shape could at
least mean a change in circumference.

For 1 complete revolution, there is no difference. Absolutely correct.
However what about 1/4 of a revolution or 1/8 of a revolution? Then
the diameter of the "big pulley" does differs.

I think that's the point of Biopace and this new system (has it got a
name yet?). The strength needed to rotate 1 cycle is equal, but with an
elliptical chainring this strength is supposed to be more equally
distributed.
Given the way everything is shaking and non-smooth there must be an
effect. I would think this effect is negative, also given the silent
passing of Biopace, but given the performance of Froome that doesn't
make sense.
I wonder: is it still possible to stand up on your pedals when you're
going uphill, or is this why Froome is almost always sitting?

Froome mostly sits because any energy used moving the body
up and down when standing is energy wasted compared to
not lifting the body and staying seated. A bicycle is a machine
which should be used for best mechanical advantage. Standing
and running on the machine as opposed to being seated on the
machine and spinning both pushing and pulling causes the machine
to become more efficient. Lifting the pedals while seated causes
more total energy to be put into the machine than lifting when
standing which mostly works against the inertia of the body mass
thus moving the body up and down with the push-pull and this
disrupts the smooth turning of circles which is more efficient
than some jerky motion.

Froome seems to have this insight. Then there's the factor
of wind resistance. Every pro should know that standing
causes more wind resistance. Why stand when it's going
to cost you watts and wear you out prematurely?

It's high time pro cyclists started relying less on drugs and
more on using their heads.

[Sir Gregory Hall, Esq·]

Post by Sir Gregory Hall, Esq·

Post by Friso

Post by none) (Yannick Tremblay

Post by Steve Freides

Post by Mower Man
Isn't it the point that elliptical chain rings actually vary the gear
ratio? Forget the number of teeth, they're only there 'cos a chain is
used. Think of diameter. Variable diameter. Honest. Think drive belt?
Big pulley vs small pulley?

But big pulley versus small pulley, first of all, means something
different for belt drive than for one with teeth. If one pedal
revolution gets you 39 teeth spaced evenly apart, what's the difference
what the shape is? For a belt driven system, a change in shape could at
least mean a change in circumference.

For 1 complete revolution, there is no difference. Absolutely correct.
However what about 1/4 of a revolution or 1/8 of a revolution? Then
the diameter of the "big pulley" does differs.

I think that's the point of Biopace and this new system (has it got a
name yet?). The strength needed to rotate 1 cycle is equal, but with an
elliptical chainring this strength is supposed to be more equally
distributed.
Given the way everything is shaking and non-smooth there must be an
effect. I would think this effect is negative, also given the silent
passing of Biopace, but given the performance of Froome that doesn't
make sense.
I wonder: is it still possible to stand up on your pedals when you're
going uphill, or is this why Froome is almost always sitting?

Froome mostly sits because any energy used moving the body
up and down when standing is energy wasted compared to
not lifting the body and staying seated. A bicycle is a machine
which should be used for best mechanical advantage. Standing
and running on the machine as opposed to being seated on the
machine and spinning both pushing and pulling causes the machine
to become (correction) LESS efficient. Lifting the pedals while seated
causes
more total energy to be put into the machine than lifting when
standing which mostly works against the inertia of the body mass
thus moving the body up and down with the push-pull and this
disrupts the smooth turning of circles which is more efficient
than some jerky motion.
Froome seems to have this insight. Then there's the factor
of wind resistance. Every pro should know that standing
causes more wind resistance. Why stand when it's going
to cost you watts and wear you out prematurely?
It's high time pro cyclists started relying less on drugs and
more on using their heads.
--
Sir Gregory

[Steve Freides]

Post by Sir Gregory Hall, Esq·
Froome mostly sits because any energy used moving the body
up and down when standing is energy wasted compared to
not lifting the body and staying seated.

Froome's height is 6 feet, 13 inches. History tells us that smaller
racers like to stand more often. Froome, who looks like Lurch, sits -
follows past precedent. The little Columbian guy, however, often
stands.

Whether it's mass or height, I couldn't say, but clearly here, size does
matter.

-S-

[Doug Anderson]

Post by Steve Freides

Post by Sir Gregory Hall, Esq·
Froome mostly sits because any energy used moving the body
up and down when standing is energy wasted compared to
not lifting the body and staying seated.

Froome's height is 6 feet, 13 inches.

Maybe he isn't quite that tall.

[Mower Man]

Post by Doug Anderson

Post by Steve Freides

Post by Sir Gregory Hall, Esq·
Froome mostly sits because any energy used moving the body
up and down when standing is energy wasted compared to
not lifting the body and staying seated.

Froome's height is 6 feet, 13 inches.

Maybe he isn't quite that tall.

Another LOB. How - given that there are 12 inches to a foot (FFS why do
you lot not use the metric system? Sooooo much simpler) is 6 feet 13
inches really 7 feet one inch?

LOB = Met Police slang, "Load of Bollocks".

[Steve Freides]

Post by Mower Man

Post by Doug Anderson

Post by Steve Freides

Post by Sir Gregory Hall, Esq·
Froome mostly sits because any energy used moving the body
up and down when standing is energy wasted compared to
not lifting the body and staying seated.

Froome's height is 6 feet, 13 inches.

Maybe he isn't quite that tall.

Another LOB. How - given that there are 12 inches to a foot (FFS why
do you lot not use the metric system? Sooooo much simpler) is 6 feet
13 inches really 7 feet one inch?
LOB = Met Police slang, "Load of Bollocks".

It was said tongue in cheek. Nudge, nudge, you know what I mean ... I
just meant that he's on the tall side.

-S-

[Mark J.]

Post by Doug Anderson

Post by Steve Freides

Post by Sir Gregory Hall, Esq·
Froome mostly sits because any energy used moving the body
up and down when standing is energy wasted compared to
not lifting the body and staying seated.

Froome's height is 6 feet, 13 inches.

Maybe he isn't quite that tall.

I knew a bike shop manager who described himself as 5 foot, 20 inches
tall. He really was.

Mark J.

[Sir Gregory Hall, Esq·]

Post by Sir Gregory Hall, Esq·
Froome mostly sits because any energy used moving the body
up and down when standing is energy wasted compared to
not lifting the body and staying seated.

Froome's height is 6 feet, 13 inches. History tells us that smaller racers
like to stand more often. Froome, who looks like Lurch, sits - follows past
precedent. The little Columbian guy, however, often stands.
Whether it's mass or height, I couldn't say, but clearly here, size does
matter.

The little Colombian climber would be better off if he would
stay in the saddle and develop his spin technique to put
forth max power with fewer calories burned. Probably he looks
at the power meter and comes to the conclusion that he creates
more power standing.

Should this be the case, then he needs to consider calories
burned vs. power output. The human body is a machine that
runs best when it stays within certain parameters. Standing
and pedaling uses more calories even if it should, for a time,
create higher wattage. Standing is probably the best thing
in a short sprint whereas over the long-haul, climbing included,
staying in the saddle will allow greater overall speeds for the
long-haul due to energy conserved. It's a fact that the human
body is able to burn calories faster than they can be replaced.

This is what bonking is all about. So, it would behoove a wise
pro cyclist to not ride so close to the ragged edge. Sitting
when climbing can develop just as much power as standing
if one develops the right technique and with that power comes
with a greater efficiency. That's called win-win in a grand classic.

[Steve Freides]

Post by Sir Gregory Hall, Esq·
The little Colombian climber would be better off if he would
stay in the saddle and develop his spin technique to put
forth max power with fewer calories burned.

You are arguing with facts. I don't know _why_ little climbers like to
stand, but it's indisputable that they do. Speaking for myself, even
though I'm not that little, I do find standing sometimes just feels
right when climbing. (I weigh 68 kg or about 150 lbs.)

-S-

[Mower Man]

Post by Steve Freides

Post by Sir Gregory Hall, Esq·
Froome mostly sits because any energy used moving the body
up and down when standing is energy wasted compared to
not lifting the body and staying seated.

Froome's height is 6 feet, 13 inches. History tells us that smaller
racers like to stand more often. Froome, who looks like Lurch, sits -
follows past precedent. The little Columbian guy, however, often
stands.
Whether it's mass or height, I couldn't say, but clearly here, size does
matter.
-S-

Hold on - how many inches are there in a foot?

Answer -

a) Over 12 inches
b) fewer (note - NOT less) than 12 inches
c) 12

OMG.

[none) (Yannick Tremblay]

Post by Friso

Post by none) (Yannick Tremblay

Post by Steve Freides

Post by Mower Man
Isn't it the point that elliptical chain rings actually vary the gear
ratio? Forget the number of teeth, they're only there 'cos a chain is
used. Think of diameter. Variable diameter. Honest. Think drive belt?
Big pulley vs small pulley?

But big pulley versus small pulley, first of all, means something
different for belt drive than for one with teeth. If one pedal
revolution gets you 39 teeth spaced evenly apart, what's the difference
what the shape is? For a belt driven system, a change in shape could at
least mean a change in circumference.

For 1 complete revolution, there is no difference. Absolutely correct.
However what about 1/4 of a revolution or 1/8 of a revolution? Then
the diameter of the "big pulley" does differs.

I think that's the point of Biopace and this new system (has it got a
name yet?). The strength needed to rotate 1 cycle is equal, but with an
elliptical chainring this strength is supposed to be more equally
distributed.

The key is that the human ability to deliver power and generate torque
varies depending on the position of the pedals.

If you had a human with perfect spinning pedalling movement able to
generate the same amount of torque at every points over 360 degs then
these system would be useless. But they are an attempt to compensate
for the imperfect human engine (and pedals).

Post by Friso
Given the way everything is shaking and non-smooth there must be an
effect. I would think this effect is negative, also given the silent
passing of Biopace, but given the performance of Froome that doesn't
make sense.

Why would you think that they have a negative effect?

Shimano, Rotors, and the like have made scientific studies on the
subject. We could dismiss some of it as marketing gimmick, other as
flawed science but I would not dismiss the Sky team and David
Brailsford.

The UK cycling team has achieved so much success in the Olympics and
WC in large part by preparing and training better, harder and more
scientifically than anyone else. Team Sky is most probably the most
scientifically trained and tested team. I would be incredibly
surprised if Chris Froome has not spent hundreds of hours on a
training bikes in the lab trying different setup including circular
chain rig and ovoid chain rig. The difference may have been only 0.5%
or even less but Brailsford believes in summing all these small minor
advantages and making it a winning difference.

I wouldn't even be surprised that the exact angle of the ovoid for
Froome differs between his mountain climbing bike and his time trial
bike and that they all differ from Wiggins ones all of that based on
labs measurement for the specific athlete under specific conditions.
Brailsford and his team are that anal with regards to details.

In act, the above probably highlight one of the problem with Biopace
in that it was one setup that may have been good for a certain type of
rider with a certain pedalling style but not for a different rider with
a different pedalling style.

Post by Friso
I wonder: is it still possible to stand up on your pedals when you're
going uphill, or is this why Froome is almost always sitting?

Hmm, not sure. In theory "dancing on a bike" is not very good and a
waste of effort in the long term although climbers like to do it for
short efforts. I don't seem to recall someone like Indurain standing
up too often either. I'd put it down to riding style.

Yani

[Friso]

Post by none) (Yannick Tremblay

Post by Friso

Post by none) (Yannick Tremblay

Post by Steve Freides

Post by Mower Man
Isn't it the point that elliptical chain rings actually vary the gear
ratio? Forget the number of teeth, they're only there 'cos a chain is
used. Think of diameter. Variable diameter. Honest. Think drive belt?
Big pulley vs small pulley?

But big pulley versus small pulley, first of all, means something
different for belt drive than for one with teeth. If one pedal
revolution gets you 39 teeth spaced evenly apart, what's the difference
what the shape is? For a belt driven system, a change in shape could at
least mean a change in circumference.

For 1 complete revolution, there is no difference. Absolutely correct.
However what about 1/4 of a revolution or 1/8 of a revolution? Then
the diameter of the "big pulley" does differs.

I think that's the point of Biopace and this new system (has it got a
name yet?). The strength needed to rotate 1 cycle is equal, but with an
elliptical chainring this strength is supposed to be more equally
distributed.

The key is that the human ability to deliver power and generate torque
varies depending on the position of the pedals.
If you had a human with perfect spinning pedalling movement able to
generate the same amount of torque at every points over 360 degs then
these system would be useless. But they are an attempt to compensate
for the imperfect human engine (and pedals).

Post by Friso
Given the way everything is shaking and non-smooth there must be an
effect. I would think this effect is negative, also given the silent
passing of Biopace, but given the performance of Froome that doesn't
make sense.

Why would you think that they have a negative effect?

First, thanks for your posts, they give a really good insight in why
this might (or might not) work.

The reason why I think it has a negative effect is non-scientific.
It doesn't look smooth, the chain is jumping, body is shaking. Part of
it is just Froome's style. Maybe the 'juming of the chain' is just the
effect of the low gears Froome is using. I mainly think that
not-smooth is not-100% effective.

Post by none) (Yannick Tremblay
Shimano, Rotors, and the like have made scientific studies on the
subject. We could dismiss some of it as marketing gimmick, other as
flawed science but I would not dismiss the Sky team and David
Brailsford.
The UK cycling team has achieved so much success in the Olympics and
WC in large part by preparing and training better, harder and more
scientifically than anyone else. Team Sky is most probably the most
scientifically trained and tested team. I would be incredibly
surprised if Chris Froome has not spent hundreds of hours on a
training bikes in the lab trying different setup including circular
chain rig and ovoid chain rig. The difference may have been only 0.5%
or even less but Brailsford believes in summing all these small minor
advantages and making it a winning difference.
I wouldn't even be surprised that the exact angle of the ovoid for
Froome differs between his mountain climbing bike and his time trial
bike and that they all differ from Wiggins ones all of that based on
labs measurement for the specific athlete under specific conditions.
Brailsford and his team are that anal with regards to details.
In act, the above probably highlight one of the problem with Biopace
in that it was one setup that may have been good for a certain type of
rider with a certain pedalling style but not for a different rider with
a different pedalling style.

That might very well be true. I would like to add another point to the
equation, which is the placebo effect. All this training and figuring
out the right ovoid might give Froome the idea that he is very ahead of
the rest, while strictly looking at the scientific facts he isn't. But
a it gives more 'morale' and therefore has a positive effect on his
perormance in the Tour.

Post by none) (Yannick Tremblay

Post by Friso
I wonder: is it still possible to stand up on your pedals when you're
going uphill, or is this why Froome is almost always sitting?

Hmm, not sure. In theory "dancing on a bike" is not very good and a
waste of effort in the long term although climbers like to do it for
short efforts. I don't seem to recall someone like Indurain standing
up too often either. I'd put it down to riding style.
Yani

[Steve Freides]

Post by none) (Yannick Tremblay

Post by Steve Freides

Post by Mower Man
Isn't it the point that elliptical chain rings actually vary the
gear ratio? Forget the number of teeth, they're only there 'cos a
chain is used. Think of diameter. Variable diameter. Honest. Think
drive belt? Big pulley vs small pulley?

But big pulley versus small pulley, first of all, means something
different for belt drive than for one with teeth. If one pedal
revolution gets you 39 teeth spaced evenly apart, what's the
difference what the shape is? For a belt driven system, a change in
shape could at least mean a change in circumference.

For 1 complete revolution, there is no difference. Absolutely
correct.
However what about 1/4 of a revolution or 1/8 of a revolution? Then
the diameter of the "big pulley" does differs.
Yan

You misread what I wrote. I don't assume that a change in circumference
matters, either - you could accomplish the same thing with a larger or
smaller, but still round, pulley.

The reason tests cannot confirm that this idea works is simple - it
doesn't. Neither the rear wheel nor your legs care about the shape of
the chainring. When you're pulling one tooth's worth of chain, that's
what you're doing, period.

-S-

[Sir Gregory Hall, Esq·]

"Steve Freides" <***@kbnj.com> wrote in message news:ksbgmf$7f0$***@speranza.aioe.org...

[trim]

Post by Steve Freides
You misread what I wrote. I don't assume that a change in circumference
matters, either - you could accomplish the same thing with a larger or
smaller, but still round, pulley.
The reason tests cannot confirm that this idea works is simple - it doesn't.
Neither the rear wheel nor your legs care about the shape of the chainring.
When you're pulling one tooth's worth of chain, that's what you're doing,
period!

BINGO!!!

[none) (Yannick Tremblay]

Post by Steve Freides

Post by none) (Yannick Tremblay

Post by Steve Freides

Post by Mower Man
Isn't it the point that elliptical chain rings actually vary the
gear ratio? Forget the number of teeth, they're only there 'cos a
chain is used. Think of diameter. Variable diameter. Honest. Think
drive belt? Big pulley vs small pulley?

But big pulley versus small pulley, first of all, means something
different for belt drive than for one with teeth. If one pedal
revolution gets you 39 teeth spaced evenly apart, what's the
difference what the shape is? For a belt driven system, a change in
shape could at least mean a change in circumference.

For 1 complete revolution, there is no difference. Absolutely correct.
However what about 1/4 of a revolution or 1/8 of a revolution? Then
the diameter of the "big pulley" does differs.
Yan

You misread what I wrote. I don't assume that a change in circumference
matters, either - you could accomplish the same thing with a larger or
smaller, but still round, pulley.
The reason tests cannot confirm that this idea works is simple - it
doesn't. Neither the rear wheel nor your legs care about the shape of
the chainring. When you're pulling one tooth's worth of chain, that's
what you're doing, period.

"When you're pulling one tooth's worth of chain"

Yes absolutely, for the *rear* cog. But how many degree of rotation
of the pedals are needed to move 1 tooth at the back?

On a circular chain rig, pulling 1 tooth of the front 36 rig
will pull 1 teeth of the rear 18 cog. This occurs on a 10 degree
rotation of the pedals regardless of the pedal position and causes a
20 degree rotation of the rear wheel.

On an ovoid chain rig however, this is not the case. While the ovoid
rotate 10 degree, its active diameter also changes. The change in
active diameter of the front can be observed by looking at the
derailler moving in an out as the front rig rotates. It is kind of
equivalent to the front rig dynamically changing between, say 35 and 37
teeth during a full rotation. (This is possible because only about
half of the front rig is touching the chain at any point in time and
there is slack in the chain). For some section of the rotation the
chain is being pulled by the rotation and is getting pulled also by
the increase in diameter while for other sections, the chain will be
pulled by the rotation but some of this will be cancelled by the
reduction in diameter. So while 360 deg front = 720 degs rear,
for some part of the rotation, 10 degree front could result in 19.5 or
20.5 degs rear (because the chain is also being pulled by the increase
in diameter) rather than a constant 20 degree. There is a difference
and this difference can be measured.

The mechanics of ovoid/biopace/etc are pretty easy to demonstrate
experimentally or prove mathematically.

What is a lot less clear are the real benefits to the cyclists.


Yan

[Sir Gregory Hall, Esq·]

Post by none) (Yannick Tremblay
On an ovoid chain rig however, this is not the case. While the ovoid
rotate 10 degree, its active diameter also changes.

Active diameter doesn't matter. Only the gear ratio matters and
that gear ration depends on number of teeth.

Post by none) (Yannick Tremblay
The change in
active diameter of the front can be observed by looking at the
derailler moving in an out as the front rig rotates. It is kind of
equivalent to the front rig dynamically changing between, say 35 and 37
teeth during a full rotation. (This is possible because only about
half of the front rig is touching the chain at any point in time and
there is slack in the chain).

Wrong! The gear ration doesn't change. Only the slack in the chain
changes depending upon the position of the shape of the chainring.
The derailleur pulleys are a chain tensioner so of course when the
chain becomes slack it takes up the slack. This doesn't mean the
gear ratio is changing. One could use a square or rectangular
chainring but if it had 53 teeth then the shape of it won't change
the gear ratio. It is gear ratio that determines mechanical advantage
not gear shape. Oddly shaped gears only result in reduced efficiency
compared to circular gears.

[Mower Man]

Post by Sir Gregory Hall, Esq·

Post by none) (Yannick Tremblay
On an ovoid chain rig however, this is not the case. While the ovoid
rotate 10 degree, its active diameter also changes.

Active diameter doesn't matter. Only the gear ratio matters and
that gear ration depends on number of teeth.

Post by none) (Yannick Tremblay
The change in
active diameter of the front can be observed by looking at the
derailler moving in an out as the front rig rotates. It is kind of
equivalent to the front rig dynamically changing between, say 35 and 37
teeth during a full rotation. (This is possible because only about
half of the front rig is touching the chain at any point in time and
there is slack in the chain).

Wrong! The gear ration doesn't change. Only the slack in the chain
changes depending upon the position of the shape of the chainring.
The derailleur pulleys are a chain tensioner so of course when the
chain becomes slack it takes up the slack. This doesn't mean the
gear ratio is changing. One could use a square or rectangular
chainring but if it had 53 teeth then the shape of it won't change
the gear ratio. It is gear ratio that determines mechanical advantage
not gear shape. Oddly shaped gears only result in reduced efficiency
compared to circular gears.

Wrong. It does. And it's so obvious as to beggar belief. The slack in
the chain is utterly irrelevant, too.

What is all this 53 tooth numbers stuff about? Old fashioned wrong
headed nonsense. The chain just is a convenient non slip way to drive
one rotating thing from another. If it was a Vee belt, what would you
then think? I assure you that the theory is the same, exactly the same.

Did you do "moments" in physics? You should have in the context of this
discussion. :-)

[Steve Freides]

Post by Mower Man
Wrong. It does. And it's so obvious as to beggar belief. The slack in
the chain is utterly irrelevant, too.

Let us consider what's happening at a point in the rotation of the
chainrings where it's clearly not round. Are you suggesting there is a
different amount of pedal travel in order to advance the chain at the
rear wheel by one link? That's the crux of the issue - you are arguing,
I believe, that the amount of pedal travel varies throughout a pedaling
circle as the shape of the chainring changes - because if it doesn't,
then there is no difference.

What really could make a difference is if the shape of the chainring
effectively changed the gear ratio during a single pedal revolution. If
that happened, then we'd be talking about something tangible, the
reduction of force required by a lower gear at the point the rider's
legs were weakest. Now that sounds like it could be truly useful.

-S-

[Mower Man]

Post by Steve Freides

Post by Mower Man
Wrong. It does. And it's so obvious as to beggar belief. The slack in
the chain is utterly irrelevant, too.

Let us consider what's happening at a point in the rotation of the
chainrings where it's clearly not round. Are you suggesting there is a
different amount of pedal travel in order to advance the chain at the
rear wheel by one link? That's the crux of the issue - you are arguing,
I believe, that the amount of pedal travel varies throughout a pedaling
circle as the shape of the chainring changes - because if it doesn't,
then there is no difference.
What really could make a difference is if the shape of the chainring
effectively changed the gear ratio during a single pedal revolution. If
that happened, then we'd be talking about something tangible, the
reduction of force required by a lower gear at the point the rider's
legs were weakest. Now that sounds like it could be truly useful.
-S-

It is. At TDC and BDC it does.

[Steve Freides]

Post by Mower Man

Post by Steve Freides

Post by Mower Man
Wrong. It does. And it's so obvious as to beggar belief. The slack
in the chain is utterly irrelevant, too.

Let us consider what's happening at a point in the rotation of the
chainrings where it's clearly not round. Are you suggesting there
is a different amount of pedal travel in order to advance the chain
at the rear wheel by one link? That's the crux of the issue - you
are arguing, I believe, that the amount of pedal travel varies
throughout a pedaling circle as the shape of the chainring changes -
because if it doesn't, then there is no difference.
What really could make a difference is if the shape of the chainring
effectively changed the gear ratio during a single pedal revolution.
If that happened, then we'd be talking about something tangible, the
reduction of force required by a lower gear at the point the rider's
legs were weakest. Now that sounds like it could be truly useful.
-S-

It is. At TDC and BDC it does.

How?

Assuming the proverbial 53-tooth chainring, doesn't one full revolution
of the pedals have to move 53 links of chain? Yes, of course it does.

But the more relevant question to this discussion is: Doesn't _any_ 1/53
of a revolution of the pedals have to move 1 link of chain?

-S-

[Sir Gregory Hall, Esq·]

Post by Mower Man

Post by Steve Freides

Post by Mower Man
Wrong. It does. And it's so obvious as to beggar belief. The slack
in the chain is utterly irrelevant, too.

Let us consider what's happening at a point in the rotation of the
chainrings where it's clearly not round. Are you suggesting there
is a different amount of pedal travel in order to advance the chain
at the rear wheel by one link? That's the crux of the issue - you
are arguing, I believe, that the amount of pedal travel varies
throughout a pedaling circle as the shape of the chainring changes -
because if it doesn't, then there is no difference.
What really could make a difference is if the shape of the chainring
effectively changed the gear ratio during a single pedal revolution.
If that happened, then we'd be talking about something tangible, the
reduction of force required by a lower gear at the point the rider's
legs were weakest. Now that sounds like it could be truly useful.

It is. At TDC and BDC it does.

How?
Assuming the proverbial 53-tooth chainring, doesn't one full revolution of
the pedals have to move 53 links of chain? Yes, of course it does.
But the more relevant question to this discussion is: Doesn't _any_ 1/53 of
a revolution of the pedals have to move 1 link of chain?

BINGO!!!!!!!!!!!! And then there's this: Advocates talk about a leverage
advantage due to the major axis of the ellipse being, in effect, a longer
lever arm. But, I maintain leverage is accounted for at the pedal and
is a result of crank arm length. Until and unless the elliptical sprocket
becomes larger along its major axis than the length of the crank arm
then no additional leverage can result from it.

[i***@yahoo.ca]

Post by Sir Gregory Hall, Esq·

Post by Mower Man

Post by Steve Freides

Post by Mower Man
Wrong. It does. And it's so obvious as to beggar belief. The slack
in the chain is utterly irrelevant, too.

Let us consider what's happening at a point in the rotation of the
chainrings where it's clearly not round. Are you suggesting there
is a different amount of pedal travel in order to advance the chain
at the rear wheel by one link? That's the crux of the issue - you
are arguing, I believe, that the amount of pedal travel varies
throughout a pedaling circle as the shape of the chainring changes -
because if it doesn't, then there is no difference.
What really could make a difference is if the shape of the chainring
effectively changed the gear ratio during a single pedal revolution.
If that happened, then we'd be talking about something tangible, the
reduction of force required by a lower gear at the point the rider's
legs were weakest. Now that sounds like it could be truly useful.

It is. At TDC and BDC it does.

How?
Assuming the proverbial 53-tooth chainring, doesn't one full revolution of
the pedals have to move 53 links of chain? Yes, of course it does.
But the more relevant question to this discussion is: Doesn't _any_ 1/53 of
a revolution of the pedals have to move 1 link of chain?

BINGO!!!!!!!!!!!! And then there's this: Advocates talk about a leverage
advantage due to the major axis of the ellipse being, in effect, a longer
lever arm. But, I maintain leverage is accounted for at the pedal and
is a result of crank arm length. Until and unless the elliptical sprocket
becomes larger along its major axis than the length of the crank arm
then no additional leverage can result from it.

I think that the idea was to change whre/how the leverage was applied. Just like when applying force to a stuck nut or bolt, the amount of leverage that can be applied by the body using the wrench increases or decreases depending where the leverage arm is located. Think of the bolt/nut as being in the center of a clock face. Depending on the hour number the handle of the lever is pointing towards can make a big difference in how much pressure one can exert on that lever. The lever length doesn't change nor does the diameter of the turning circle of that lever but the amount of leverage that can be applied does change because more force can be applied.

Cheers

[Sir Gregory Hall, Esq·]

Post by Sir Gregory Hall, Esq·

Post by Mower Man

Post by Steve Freides

Post by Mower Man
Wrong. It does. And it's so obvious as to beggar belief. The slack
in the chain is utterly irrelevant, too.

Let us consider what's happening at a point in the rotation of the
chainrings where it's clearly not round. Are you suggesting there
is a different amount of pedal travel in order to advance the chain
at the rear wheel by one link? That's the crux of the issue - you
are arguing, I believe, that the amount of pedal travel varies
throughout a pedaling circle as the shape of the chainring changes -
because if it doesn't, then there is no difference.
What really could make a difference is if the shape of the chainring
effectively changed the gear ratio during a single pedal revolution.
If that happened, then we'd be talking about something tangible, the
reduction of force required by a lower gear at the point the rider's
legs were weakest. Now that sounds like it could be truly useful.

It is. At TDC and BDC it does.

How?
Assuming the proverbial 53-tooth chainring, doesn't one full revolution of
the pedals have to move 53 links of chain? Yes, of course it does.
But the more relevant question to this discussion is: Doesn't _any_ 1/53 of
a revolution of the pedals have to move 1 link of chain?

BINGO!!!!!!!!!!!! And then there's this: Advocates talk about a leverage
advantage due to the major axis of the ellipse being, in effect, a longer
lever arm. But, I maintain leverage is accounted for at the pedal and
is a result of crank arm length. Until and unless the elliptical sprocket
becomes larger along its major axis than the length of the crank arm
then no additional leverage can result from it.

I think that the idea was to change whre/how the leverage was applied. Just
like when applying force to a stuck nut or bolt, the amount of leverage that
can be applied by the body using the wrench increases or decreases depending
where the leverage arm is located. Think of the bolt/nut as being in the
center of a clock face. Depending on the hour number the handle of the lever
is pointing towards can make a big difference in how much pressure one can
exert on that lever. The lever length doesn't change nor does the diameter of
the turning circle of that lever but the amount of leverage that can be
applied does change because more force can be applied.

Cheers



=====================[reply]===========================

That's all well and good but let's place an 11 tooth sprocket on the bolt or
nut. Then let's place a 53-tooth chainring on the wrench and connect them with
a chain. Then let's spin the wrench. The force applied to the wrench is
directly applied to the 53-tooth chainring and transferred via the chain to
the 11-tooth sprocket on the bolt or nut.

It is the gear ratio alone that and applies X amount of torque. It doesn't
matter one iota if the 53-tooth chainring is elliptical in shape as long as
the wrench is longer than the major axis of the elliptical chainring. The
false illusion of a different gear ration due to the placement of the
elliptical chainring belies the fact that it is still only the gear ratio that
affects the torque value.

Cheerio!

[i***@yahoo.ca]

Post by i***@yahoo.ca

Post by Sir Gregory Hall, Esq·

Post by Mower Man

Post by Steve Freides

Post by Mower Man
Wrong. It does. And it's so obvious as to beggar belief. The slack
in the chain is utterly irrelevant, too.

Let us consider what's happening at a point in the rotation of the
chainrings where it's clearly not round. Are you suggesting there
is a different amount of pedal travel in order to advance the chain
at the rear wheel by one link? That's the crux of the issue - you
are arguing, I believe, that the amount of pedal travel varies
throughout a pedaling circle as the shape of the chainring changes -
because if it doesn't, then there is no difference.
What really could make a difference is if the shape of the chainring
effectively changed the gear ratio during a single pedal revolution.
If that happened, then we'd be talking about something tangible, the
reduction of force required by a lower gear at the point the rider's
legs were weakest. Now that sounds like it could be truly useful.

It is. At TDC and BDC it does.

How?
Assuming the proverbial 53-tooth chainring, doesn't one full revolution of
the pedals have to move 53 links of chain? Yes, of course it does.
But the more relevant question to this discussion is: Doesn't _any_ 1/53
of
a revolution of the pedals have to move 1 link of chain?

BINGO!!!!!!!!!!!! And then there's this: Advocates talk about a leverage
advantage due to the major axis of the ellipse being, in effect, a longer
lever arm. But, I maintain leverage is accounted for at the pedal and
is a result of crank arm length. Until and unless the elliptical sprocket
becomes larger along its major axis than the length of the crank arm
then no additional leverage can result from it.

I think that the idea was to change whre/how the leverage was applied. Just
like when applying force to a stuck nut or bolt, the amount of leverage that
can be applied by the body using the wrench increases or decreases depending
where the leverage arm is located. Think of the bolt/nut as being in the
center of a clock face. Depending on the hour number the handle of the lever
is pointing towards can make a big difference in how much pressure one can
exert on that lever. The lever length doesn't change nor does the diameter of
the turning circle of that lever but the amount of leverage that can be
applied does change because more force can be applied.
Cheers
=====================[reply]===========================
That's all well and good but let's place an 11 tooth sprocket on the bolt or
nut. Then let's place a 53-tooth chainring on the wrench and connect them with
a chain. Then let's spin the wrench. The force applied to the wrench is
directly applied to the 53-tooth chainring and transferred via the chain to
the 11-tooth sprocket on the bolt or nut.
It is the gear ratio alone that and applies X amount of torque. It doesn't
matter one iota if the 53-tooth chainring is elliptical in shape as long as
the wrench is longer than the major axis of the elliptical chainring. The
false illusion of a different gear ration due to the placement of the
elliptical chainring belies the fact that it is still only the gear ratio that
affects the torque value.
Cheerio!

A lot of times when trying to loosen a tight nut or bolt, if you place the handle of the wrench lower than 12 o'clock you can exert more pressure onto the handle but *NOTHING* else has changed. That's what the eliptical chainring does. It allows more force to be applied at the former deadzones of TDC and BDC. The gear size (effective diameter of a direct drive wheel) doesn't change nor does the length of tthe lever - just the amount of force that can be applied to that lever.

Cheers

[Sir Gregory Hall, Esq·]

Post by i***@yahoo.ca

Post by Sir Gregory Hall, Esq·

Post by Mower Man

Post by Steve Freides

Post by Mower Man
Wrong. It does. And it's so obvious as to beggar belief. The slack
in the chain is utterly irrelevant, too.

Let us consider what's happening at a point in the rotation of the
chainrings where it's clearly not round. Are you suggesting there
is a different amount of pedal travel in order to advance the chain
at the rear wheel by one link? That's the crux of the issue - you
are arguing, I believe, that the amount of pedal travel varies
throughout a pedaling circle as the shape of the chainring changes -
because if it doesn't, then there is no difference.
What really could make a difference is if the shape of the chainring
effectively changed the gear ratio during a single pedal revolution.
If that happened, then we'd be talking about something tangible, the
reduction of force required by a lower gear at the point the rider's
legs were weakest. Now that sounds like it could be truly useful.

It is. At TDC and BDC it does.

How?
Assuming the proverbial 53-tooth chainring, doesn't one full revolution of
the pedals have to move 53 links of chain? Yes, of course it does.
But the more relevant question to this discussion is: Doesn't _any_ 1/53
of
a revolution of the pedals have to move 1 link of chain?

BINGO!!!!!!!!!!!! And then there's this: Advocates talk about a leverage
advantage due to the major axis of the ellipse being, in effect, a longer
lever arm. But, I maintain leverage is accounted for at the pedal and
is a result of crank arm length. Until and unless the elliptical sprocket
becomes larger along its major axis than the length of the crank arm
then no additional leverage can result from it.

I think that the idea was to change whre/how the leverage was applied. Just
like when applying force to a stuck nut or bolt, the amount of leverage that
can be applied by the body using the wrench increases or decreases depending
where the leverage arm is located. Think of the bolt/nut as being in the
center of a clock face. Depending on the hour number the handle of the lever
is pointing towards can make a big difference in how much pressure one can
exert on that lever. The lever length doesn't change nor does the diameter of
the turning circle of that lever but the amount of leverage that can be
applied does change because more force can be applied.
Cheers
=====================[reply]===========================
That's all well and good but let's place an 11 tooth sprocket on the bolt or
nut. Then let's place a 53-tooth chainring on the wrench and connect them with
a chain. Then let's spin the wrench. The force applied to the wrench is
directly applied to the 53-tooth chainring and transferred via the chain to
the 11-tooth sprocket on the bolt or nut.
It is the gear ratio alone that and applies X amount of torque. It doesn't
matter one iota if the 53-tooth chainring is elliptical in shape as long as
the wrench is longer than the major axis of the elliptical chainring. The
false illusion of a different gear ration due to the placement of the
elliptical chainring belies the fact that it is still only the gear ratio that
affects the torque value.
Cheerio!

A lot of times when trying to loosen a tight nut or bolt, if you place the
handle of the wrench lower than 12 o'clock you can exert more pressure onto
the handle but *NOTHING* else has changed. That's what the eliptical chainring
does. It allows more force to be applied at the former deadzones of TDC and
BDC. The gear size (effective diameter of a direct drive wheel) doesn't change
nor does the length of tthe lever - just the amount of force that can be
applied to that lever.

Cheers



===================[reply]======================

I understand what you're claiming but I reject it outright.
Why? Because what one may gain one place on the
ellipses one necessarily loses it in another and the
inefficiencies inherent in the system (such as the derailleur
tensioner spring being unwound and wound to take
up erratic chain slack) compound the loss. With a
circular chainring such inefficiencies and losses are
minimized.

As for being able to apply more force to a lever in
a certain optimal position that would be great provided
the lever always maintained that optimal position. It
does not and the loss becomes greater in the
less optimal positions. You end up with net loss in
power transfer over the more efficient circular
shape.

Cheerio

[i***@yahoo.ca]

Post by i***@yahoo.ca

Post by i***@yahoo.ca

Post by Sir Gregory Hall, Esq·

Post by Steve Freides

Post by Mower Man

Post by Steve Freides

Post by Mower Man
Wrong. It does. And it's so obvious as to beggar belief. The slack
in the chain is utterly irrelevant, too.

Let us consider what's happening at a point in the rotation of the
chainrings where it's clearly not round. Are you suggesting there
is a different amount of pedal travel in order to advance the chain
at the rear wheel by one link? That's the crux of the issue - you
are arguing, I believe, that the amount of pedal travel varies
throughout a pedaling circle as the shape of the chainring changes -
because if it doesn't, then there is no difference.
What really could make a difference is if the shape of the chainring
effectively changed the gear ratio during a single pedal revolution.
If that happened, then we'd be talking about something tangible, the
reduction of force required by a lower gear at the point the rider's
legs were weakest. Now that sounds like it could be truly useful.

It is. At TDC and BDC it does.

How?
Assuming the proverbial 53-tooth chainring, doesn't one full revolution
of
the pedals have to move 53 links of chain? Yes, of course it does.
But the more relevant question to this discussion is: Doesn't _any_ 1/53
of
a revolution of the pedals have to move 1 link of chain?

BINGO!!!!!!!!!!!! And then there's this: Advocates talk about a leverage
advantage due to the major axis of the ellipse being, in effect, a longer
lever arm. But, I maintain leverage is accounted for at the pedal and
is a result of crank arm length. Until and unless the elliptical sprocket
becomes larger along its major axis than the length of the crank arm
then no additional leverage can result from it.

I think that the idea was to change whre/how the leverage was applied. Just
like when applying force to a stuck nut or bolt, the amount of leverage that
can be applied by the body using the wrench increases or decreases depending
where the leverage arm is located. Think of the bolt/nut as being in the
center of a clock face. Depending on the hour number the handle of the lever
is pointing towards can make a big difference in how much pressure one can
exert on that lever. The lever length doesn't change nor does the diameter
of
the turning circle of that lever but the amount of leverage that can be
applied does change because more force can be applied.
Cheers
=====================[reply]===========================
That's all well and good but let's place an 11 tooth sprocket on the bolt or
nut. Then let's place a 53-tooth chainring on the wrench and connect them
with
a chain. Then let's spin the wrench. The force applied to the wrench is
directly applied to the 53-tooth chainring and transferred via the chain to
the 11-tooth sprocket on the bolt or nut.
It is the gear ratio alone that and applies X amount of torque. It doesn't
matter one iota if the 53-tooth chainring is elliptical in shape as long as
the wrench is longer than the major axis of the elliptical chainring. The
false illusion of a different gear ration due to the placement of the
elliptical chainring belies the fact that it is still only the gear ratio
that
affects the torque value.
Cheerio!

A lot of times when trying to loosen a tight nut or bolt, if you place the
handle of the wrench lower than 12 o'clock you can exert more pressure onto
the handle but *NOTHING* else has changed. That's what the eliptical chainring
does. It allows more force to be applied at the former deadzones of TDC and
BDC. The gear size (effective diameter of a direct drive wheel) doesn't change
nor does the length of tthe lever - just the amount of force that can be
applied to that lever.
Cheers
===================[reply]======================
I understand what you're claiming but I reject it outright.
Why? Because what one may gain one place on the
ellipses one necessarily loses it in another and the
inefficiencies inherent in the system (such as the derailleur
tensioner spring being unwound and wound to take
up erratic chain slack) compound the loss. With a
circular chainring such inefficiencies and losses are
minimized.
As for being able to apply more force to a lever in
a certain optimal position that would be great provided
the lever always maintained that optimal position. It
does not and the loss becomes greater in the
less optimal positions. You end up with net loss in
power transfer over the more efficient circular
shape.
Cheerio

No, I don't think you lose it elsewhere because elsewhere the chainring is back to be more nearlt the normal circular ring.

I also think that the friction loss in the derailleur is minimal and that the added apploed force at the crankset is far greater than those losses.

Someplace where I really noticed the Bio Pace benefit was seated hill climbing.

Cheers

[Sir Gregory Hall, Esq·]

<***@yahoo.ca> wrote in message news:07bfc11c-90b7-4d62-bd87-***@googlegroups.com...


[big trim]

Post by i***@yahoo.ca
No, I don't think you lose it elsewhere because elsewhere the
chainring is back to be more nearlt the normal circular ring.
I also think that the friction loss in the derailleur is minimal and
that the added apploed force at the crankset is far greater than
those losses.
Someplace where I really noticed the Bio Pace benefit was
seated hill climbing.

This is all to say if you cut off six inches from one end of a
blanket and sew it on the other end you will end up with a
longer blanket.

Simply not so!

[Steve Freides]

Post by i***@yahoo.ca
A lot of times when trying to loosen a tight nut or bolt, if you
place the handle of the wrench lower than 12 o'clock you can exert
more pressure onto the handle but *NOTHING* else has changed. That's
what the eliptical chainring does. It allows more force to be applied
at the former deadzones of TDC and BDC. The gear size (effective
diameter of a direct drive wheel) doesn't change nor does the length
of tthe lever - just the amount of force that can be applied to that
lever.

We need to send you back to science class. How does the shape of the
chainring allow you to apply a different amount of force.

-S-

[atriage]

Post by Steve Freides

Post by i***@yahoo.ca
A lot of times when trying to loosen a tight nut or bolt, if you
place the handle of the wrench lower than 12 o'clock you can exert
more pressure onto the handle but *NOTHING* else has changed. That's
what the eliptical chainring does. It allows more force to be applied
at the former deadzones of TDC and BDC. The gear size (effective
diameter of a direct drive wheel) doesn't change nor does the length
of tthe lever - just the amount of force that can be applied to that
lever.

We need to send you back to science class. How does the shape of the
chainring allow you to apply a different amount of force.

Did you go to any kind of school at all?
http://www.thefreedictionary.com/torque

[Steve Freides]

Post by atriage

Post by Steve Freides

Post by i***@yahoo.ca
A lot of times when trying to loosen a tight nut or bolt, if you
place the handle of the wrench lower than 12 o'clock you can exert
more pressure onto the handle but *NOTHING* else has changed. That's
what the eliptical chainring does. It allows more force to be
applied at the former deadzones of TDC and BDC. The gear size
(effective diameter of a direct drive wheel) doesn't change nor
does the length of tthe lever - just the amount of force that can
be applied to that lever.

We need to send you back to science class. How does the shape of the
chainring allow you to apply a different amount of force.

Did you go to any kind of school at all?
http://www.thefreedictionary.com/torque

Several, in fact.

-S-

[Mower Man]

Post by Steve Freides

Post by Mower Man

Post by Steve Freides

Post by Mower Man
Wrong. It does. And it's so obvious as to beggar belief. The slack
in the chain is utterly irrelevant, too.

Let us consider what's happening at a point in the rotation of the
chainrings where it's clearly not round. Are you suggesting there
is a different amount of pedal travel in order to advance the chain
at the rear wheel by one link? That's the crux of the issue - you
are arguing, I believe, that the amount of pedal travel varies
throughout a pedaling circle as the shape of the chainring changes -
because if it doesn't, then there is no difference.
What really could make a difference is if the shape of the chainring
effectively changed the gear ratio during a single pedal revolution.
If that happened, then we'd be talking about something tangible, the
reduction of force required by a lower gear at the point the rider's
legs were weakest. Now that sounds like it could be truly useful.
-S-

It is. At TDC and BDC it does.

How?
Assuming the proverbial 53-tooth chainring, doesn't one full revolution
of the pedals have to move 53 links of chain? Yes, of course it does.
But the more relevant question to this discussion is: Doesn't _any_ 1/53
of a revolution of the pedals have to move 1 link of chain?
-S-

You need to abandon the idea that the number of links is the thing. It's
not. It's the effective diameter of the chainwheel.

[Bertrand]

Post by Steve Freides
Assuming the proverbial 53-tooth chainring, doesn't one full revolution
of the pedals have to move 53 links of chain? Yes, of course it does.
But the more relevant question to this discussion is: Doesn't _any_ 1/53
of a revolution of the pedals have to move 1 link of chain?

No, that's the key. The angle the crank moves is equal to the chain spacing
(1/2 inch) divided by what I'll call the "effective radius" of the
chainring - the distance from the center of the crank to the point where the
chainring contacts the chain (exerts force on the chain), at the top. When
Froome's crank arms are horizontal, the contact point of the chain is far
from the center, so a smaller change in crank angle pulls one link of chain,
corresponding to a higher gear.

[atriage]

Post by Bertrand

Post by Steve Freides
Assuming the proverbial 53-tooth chainring, doesn't one full revolution
of the pedals have to move 53 links of chain? Yes, of course it does.
But the more relevant question to this discussion is: Doesn't _any_ 1/53
of a revolution of the pedals have to move 1 link of chain?

No, that's the key. The angle the crank moves is equal to the chain
spacing (1/2 inch) divided by what I'll call the "effective radius" of
the chainring - the distance from the center of the crank to the point
where the chainring contacts the chain (exerts force on the chain), at
the top. When Froome's crank arms are horizontal, the contact point of
the chain is far from the center, so a smaller change in crank angle
pulls one link of chain, corresponding to a higher gear.

Correct and nicely explained.

[Phil H]

Post by atriage

Post by Bertrand

Post by Steve Freides
Assuming the proverbial 53-tooth chainring, doesn't one full revolution
of the pedals have to move 53 links of chain? Yes, of course it does.
But the more relevant question to this discussion is: Doesn't _any_ 1/53
of a revolution of the pedals have to move 1 link of chain?

No, that's the key. The angle the crank moves is equal to the chain
spacing (1/2 inch) divided by what I'll call the "effective radius" of
the chainring - the distance from the center of the crank to the point
where the chainring contacts the chain (exerts force on the chain), at
the top. When Froome's crank arms are horizontal, the contact point of
the chain is far from the center, so a smaller change in crank angle
pulls one link of chain, corresponding to a higher gear.

Correct and nicely explained.

The teeth are not really relevant in gearing except to provide a method of calculating the geat ratios. All they do really is prevent the drive belt (chain) from slipping on the gears. It is the effective diameters of the gears and chain rings that provide the gear ratios and with an eliptical chain ring, because the radius varies then so does the instantaneous effective gear ratio. Although an eliptical and a round chain ring can have the same number of teeth, that just means the average ratio for both is the same over one revolution. The eliptical will have postitions where the ratio is both higher and lower making the average ratio the same over one revolution. In reality, and this is why I don't think they work, the foot speed varies over one revolution of the crank even though the rider speed stays almost constant. This constant accelerating and decelerating of the feet and pedals can't be efficient. My 2 cents FWIW.

[atriage]

[snip]

Post by Phil H
This constant accelerating and decelerating of the feet and pedals can't be efficient. My 2 cents FWIW.

I suspect that whether or not that matters comes down to how it feels to
the rider. These guys report that it felt jerky at first but that they
got used to it quite quickly. I'm vaguely thinking of getting one since
they hardly break the bank. What concerns me most about them is the
chain whip they produce which I instinctively don't like.


http://www.artscyclery.com/reviews/RTQRS/RTQRSreview.html


"The difference in feel was immediately noticeable and my pedal stroke
felt uneven at first, but not in a jarring way. On my first ride I
noticed I was able to engage my hamstring muscles more effectively near
the bottom of the pedal stoke. By the third ride, I was spinning faster
than before and any feelings of unevenness were gone. My pedal stroke is
now as smooth as ever, and I don’t notice the rotor rings at all. It
genuinely feels like the power producing area of my pedal stroke is
larger than with normal rings."

[atriage]

Post by atriage
[snip]

Post by Phil H
This constant accelerating and decelerating of the feet and pedals
can't be efficient. My 2 cents FWIW.

I suspect that whether or not that matters comes down to how it feels to
the rider. These guys report that it felt jerky at first but that they
got used to it quite quickly. I'm vaguely thinking of getting one since
they hardly break the bank. What concerns me most about them is the
chain whip they produce which I instinctively don't like.
http://www.artscyclery.com/reviews/RTQRS/RTQRSreview.html

Here's some bike porn featuring Q rings.
http://www.cyclingweekly.co.uk/news/product/539556/tour-de-france-bike-maxime-mederel-s-bh-aero.html

[Mower Man]

Post by atriage

Post by Bertrand

Post by Steve Freides
Assuming the proverbial 53-tooth chainring, doesn't one full revolution
of the pedals have to move 53 links of chain? Yes, of course it does.
But the more relevant question to this discussion is: Doesn't _any_ 1/53
of a revolution of the pedals have to move 1 link of chain?

No, that's the key. The angle the crank moves is equal to the chain
spacing (1/2 inch) divided by what I'll call the "effective radius" of
the chainring - the distance from the center of the crank to the point
where the chainring contacts the chain (exerts force on the chain), at
the top. When Froome's crank arms are horizontal, the contact point of
the chain is far from the center, so a smaller change in crank angle
pulls one link of chain, corresponding to a higher gear.

Correct and nicely explained.

+1

[i***@yahoo.ca]

Post by Mower Man

Post by Steve Freides

Post by Mower Man
Wrong. It does. And it's so obvious as to beggar belief. The slack in
the chain is utterly irrelevant, too.

Let us consider what's happening at a point in the rotation of the
chainrings where it's clearly not round. Are you suggesting there is a
different amount of pedal travel in order to advance the chain at the
rear wheel by one link? That's the crux of the issue - you are arguing,
I believe, that the amount of pedal travel varies throughout a pedaling
circle as the shape of the chainring changes - because if it doesn't,
then there is no difference.
What really could make a difference is if the shape of the chainring
effectively changed the gear ratio during a single pedal revolution. If
that happened, then we'd be talking about something tangible, the
reduction of force required by a lower gear at the point the rider's
legs were weakest. Now that sounds like it could be truly useful.
-S-

It is. At TDC and BDC it does.
--
Chris
'Fashion is a form of ugliness so intolerable that we have to alter it
every six months.'
(Oscar Wilde.)

I remember Shimano saying that Bio Pace was designed to eliminate the dead zone at TDC and BDC. In other words BP allowed tthe bicyclist to maintain the same pressure on the crank arms throughout the entire revolution. The design of the eliptical rings was such that in effect there was no longer a real TDC or BDC.

Cheers

[Mower Man]

Post by i***@yahoo.ca

Post by Mower Man

Post by Steve Freides

Post by Mower Man
Wrong. It does. And it's so obvious as to beggar belief. The slack in
the chain is utterly irrelevant, too.

Let us consider what's happening at a point in the rotation of the
chainrings where it's clearly not round. Are you suggesting there is a
different amount of pedal travel in order to advance the chain at the
rear wheel by one link? That's the crux of the issue - you are arguing,
I believe, that the amount of pedal travel varies throughout a pedaling
circle as the shape of the chainring changes - because if it doesn't,
then there is no difference.
What really could make a difference is if the shape of the chainring
effectively changed the gear ratio during a single pedal revolution. If
that happened, then we'd be talking about something tangible, the
reduction of force required by a lower gear at the point the rider's
legs were weakest. Now that sounds like it could be truly useful.
-S-

It is. At TDC and BDC it does.
--
Chris
'Fashion is a form of ugliness so intolerable that we have to alter it
every six months.'
(Oscar Wilde.)

I remember Shimano saying that Bio Pace was designed to eliminate the dead zone at TDC and BDC. In other words

BP allowed tthe bicyclist to maintain the same pressure on the crank
arms throughout the entire revolution.

The design of the eliptical rings was such that in effect there was no
longer a real TDC or BDC.

Post by i***@yahoo.ca
Cheers

Kind of, yes!

[none) (Yannick Tremblay]

Post by Steve Freides

Post by Mower Man
Wrong. It does. And it's so obvious as to beggar belief. The slack in
the chain is utterly irrelevant, too.

Let us consider what's happening at a point in the rotation of the
chainrings where it's clearly not round. Are you suggesting there is a
different amount of pedal travel in order to advance the chain at the
rear wheel by one link? That's the crux of the issue - you are arguing,
I believe, that the amount of pedal travel varies throughout a pedaling
circle as the shape of the chainring changes - because if it doesn't,
then there is no difference.

The pedal still travel over a perfect circle but not the chain.
So for a given travel of the pedal, the chain travel a different
amount or if you prefer, to achieve a given amount of travel of the
chain, the amount of travel needed by the pedals varies.

Post by Steve Freides
What really could make a difference is if the shape of the chainring
effectively changed the gear ratio during a single pedal revolution. If
that happened, then we'd be talking about something tangible, the
reduction of force required by a lower gear at the point the rider's
legs were weakest. Now that sounds like it could be truly useful.

We are talking about definite physical, mechanical differences. This
is a hard fact.

OK, last try at explaining this:

The precise maths for the elipse of ovoid require inifite series and
usenet is maybe not the ideal place to go there so please allow me to
try to simplify by using a square.

1- chain, teeth, strap, pulley, gear, etc

Some peoples have been focusing in teeth too much.

Can we all agree that any of the following is equivalent:

Front = 40 teeth Rear = 20 teeth
Front = 400 teeth Rear = 200 teeth
Front = 4000 teeth Rear = 2000 teeth
Front = 4 million teeth Rear = 2 millions teeth
Front = 4 billion teeth Rear = 2 billion teeth

There's no difference in the gearing for any of the above.

So for the sake of simplicity, I'll continue this with a case of a
front rig with 8000 teeth with each teeth being 0.1mm.

2- The pedal move along a circle.

I think we all agree with this.

3- The chain rig is solidly attach to the pedal. Rotating the pedal
10 degrees rotate the chain rig 10 degrees around its point of
rotation regardless of the shape.

4- The chain is always in contact with the front part of the rig so it
will follow the perimeter of the rig.

5- Circular chain rig:
my 8000 teeth chain rig is 800.0 mm in circumference, it has a radius
of 127.3mm and a diameter of 254.6 mm (i.e. 800.0/Pi)

If you rotate the pedal 1/16th of a rotation (22.5 degree), the rig
will rotate 22.5 degree and the chain will be pulled by the length of
an arc of 22.5 degree with a radius of 127.3mm which is 50.0mm. As
this is a perfect circle, this is also 1/16th of the total
circumference. This will pull 500 teeth on the chain.

Since this is a perfect circle, all possible segments of 22.5 degree
are identical to any other segment.

6- Square chain rig

Now let's replace our circle chain rig with a square one.
This is a square with each side 200.0mm long.

(bad ascii art for orientation reference:
___
| . |
|___|

The perimeter of the square is 4*200.0mm = 800.0mm. This is the same
perimeter as our circular chain rig. This square also has 8000
teeth and a full 360 deg rotation with pull 8000 teeth on the chain.

If you draw a vertical or horizontal line from the center of the
square to the edge, it will be 100.0mm

If you draw a diagonal line to the corner, it will be 141.4mm
(i.e. ( 1/sin(45) ) * 100.0mm )

The pedal however are still going around in a circle. So what happens
if we compute the length of a partial rotation of the square. The
simplest way to compute this is to draw right-angle triangle and use
trigonometry.

Let's try 45 degrees: We can draw that this will go from the
horizontal to the 45 deg angle and visually we can se that this will
be 100.0mm. Trigonometry also shows that this is 100.0mm
(tan(45)*100.0mm) as expected.

What about 22.5 degree: From 0 to 22.5 degree, the length of the
perimeter section is tan(22.5) * 100.0 = 41.4mm.

The length of the section from 22.5 to 45 degree is:
(tan(45)*100.0mm) - (tan(22.5)*100.0mm) = 58.6mm

22.5 degree rotation centered over the center of the flat bit:
The length of the section from -11.25 to +11.25 is:
(tan(-11.25)*100.0mm)+(tan(11.25)*100.0mm)= 39.8mm

22.5 degree rotation centered over the corner:
The length of the section from 33.75 to 56.25 is:
((tan(45)*100.0)-(tan(33.75)*100.0)) * 2 = 66.36mm

So basically, if we turn the pedals 22.5 degree (along the circular
movement of the pedal), the amount the chain will be pulled depends on
the position of the square.

0 to 22.5 deg => 41.4mm =~ 414 teeth
22.5 to 45 deg => 58.6mm =~ 586 teeth
45 to 67.5 => 58.6mm =~ 586 teeth
67.5 to 90 => 41.4mm =~ 414 teeth

-11.25 to 11.25 deg => 39.8mm =~ 398 teeth
11.25 to 33.75 deg => 46.9mm =~ 469 teeth
33.75 to 56.25 => 66.4mm =~ 664 teeth
56.25 to 78.75 => 46.9mm =~ 469 teeth

There is still exactly 200.0mm per 90 degree but some subsections result
in more mm. There's still exactly 2000 teeth per 90 degree rotation and
8000 teeth per 360 degree.

7: elipse, ovoid or any other shape:

The same principle applies. The maths just become a bit more
complicated and you may need infinite series to get the exact result.
Visually, it is noticeable looking at:
Loading Image...
that the speed of travel of the point on the circle is constant but the
speed of travel of the point on the elipse varies, sometime being
faster and sometimes slower. This is also what happens would happen
to a chain on an elipse.

If you want more details, you could look at papers such as:
http://www.noncircularchainring.be/pdf/Biomechanical%20study%20chainrings%20-%20release%202.pdf
The purely mechanical section of this paper is irrefutable. They
compute the angular velocity of various chainrig using AutoCAD and
MATLAB. The biomechanical section where they produce an equation to
model the human is where there is room for interpretation.

Some manufacturers also have literature on their site on the subject.

Yannick
(sorry about the long message but this is not pantomine, this is
science and facts)

[Steve Freides]

Post by none) (Yannick Tremblay
So basically, if we turn the pedals 22.5 degree (along the circular
movement of the pedal), the amount the chain will be pulled depends on
the position of the square.
0 to 22.5 deg => 41.4mm =~ 414 teeth
22.5 to 45 deg => 58.6mm =~ 586 teeth
45 to 67.5 => 58.6mm =~ 586 teeth
67.5 to 90 => 41.4mm =~ 414 teeth
-11.25 to 11.25 deg => 39.8mm =~ 398 teeth
11.25 to 33.75 deg => 46.9mm =~ 469 teeth
33.75 to 56.25 => 66.4mm =~ 664 teeth
56.25 to 78.75 => 46.9mm =~ 469 teeth
There is still exactly 200.0mm per 90 degree but some subsections
result in more mm. There's still exactly 2000 teeth per 90 degree
rotation and 8000 teeth per 360 degree.
The same principle applies. The maths just become a bit more
complicated and you may need infinite series to get the exact result.
http://en.wikipedia.org/wiki/File:Parametric_ellipse.gif
that the speed of travel of the point on the circle is constant but
the speed of travel of the point on the elipse varies, sometime being
faster and sometimes slower. This is also what happens would happen
to a chain on an elipse.
http://www.noncircularchainring.be/pdf/Biomechanical%20study%20chainrings%20-%20release%202.pdf
The purely mechanical section of this paper is irrefutable. They
compute the angular velocity of various chainrig using AutoCAD and
MATLAB. The biomechanical section where they produce an equation to
model the human is where there is room for interpretation.
Some manufacturers also have literature on their site on the subject.
Yannick
(sorry about the long message but this is not pantomine, this is
science and facts)

This makes some sense to me. What you are saying is that a non-round
chainring will pull more, or fewer, chain links/teeth through a
particular section of the pedalling circle, effectively changing the
gearing during the time - more chain pulled is the same as having a
stiffer, bigger gear, and less chain pulled is the same as having a
smaller gear.

So the net effect, you're saying, is to give an easier to pedal, smaller
gear where we we are weakest in the pedalling cicle, and a stiffer gear
where we have more strength - is that what you're saying?

-S-

[none) (Yannick Tremblay]

Post by Steve Freides

Post by none) (Yannick Tremblay
So basically, if we turn the pedals 22.5 degree (along the circular
movement of the pedal), the amount the chain will be pulled depends on
the position of the square.
0 to 22.5 deg => 41.4mm =~ 414 teeth
22.5 to 45 deg => 58.6mm =~ 586 teeth
45 to 67.5 => 58.6mm =~ 586 teeth
67.5 to 90 => 41.4mm =~ 414 teeth
-11.25 to 11.25 deg => 39.8mm =~ 398 teeth
11.25 to 33.75 deg => 46.9mm =~ 469 teeth
33.75 to 56.25 => 66.4mm =~ 664 teeth
56.25 to 78.75 => 46.9mm =~ 469 teeth
There is still exactly 200.0mm per 90 degree but some subsections
result in more mm. There's still exactly 2000 teeth per 90 degree
rotation and 8000 teeth per 360 degree.
The same principle applies. The maths just become a bit more
complicated and you may need infinite series to get the exact result.
http://en.wikipedia.org/wiki/File:Parametric_ellipse.gif
that the speed of travel of the point on the circle is constant but
the speed of travel of the point on the elipse varies, sometime being
faster and sometimes slower. This is also what happens would happen
to a chain on an elipse.
http://www.noncircularchainring.be/pdf/Biomechanical%20study%20chainrings%20-%20release%202.pdf
The purely mechanical section of this paper is irrefutable. They
compute the angular velocity of various chainrig using AutoCAD and
MATLAB. The biomechanical section where they produce an equation to
model the human is where there is room for interpretation.
Some manufacturers also have literature on their site on the subject.
Yannick
(sorry about the long message but this is not pantomine, this is
science and facts)

This makes some sense to me. What you are saying is that a non-round
chainring will pull more, or fewer, chain links/teeth through a
particular section of the pedalling circle, effectively changing the
gearing during the time - more chain pulled is the same as having a
stiffer, bigger gear, and less chain pulled is the same as having a
smaller gear.

Yes

Post by Steve Freides
So the net effect, you're saying, is to give an easier to pedal, smaller
gear where we we are weakest in the pedalling cicle, and a stiffer gear
where we have more strength - is that what you're saying?

Yes
(depending on the specific shape of the rig and the specific
alignment.)

[Sir Gregory Hall, Esq·]

Post by none) (Yannick Tremblay

Post by Steve Freides

Post by none) (Yannick Tremblay
So basically, if we turn the pedals 22.5 degree (along the circular
movement of the pedal), the amount the chain will be pulled depends on
the position of the square.
0 to 22.5 deg => 41.4mm =~ 414 teeth
22.5 to 45 deg => 58.6mm =~ 586 teeth
45 to 67.5 => 58.6mm =~ 586 teeth
67.5 to 90 => 41.4mm =~ 414 teeth
-11.25 to 11.25 deg => 39.8mm =~ 398 teeth
11.25 to 33.75 deg => 46.9mm =~ 469 teeth
33.75 to 56.25 => 66.4mm =~ 664 teeth
56.25 to 78.75 => 46.9mm =~ 469 teeth
There is still exactly 200.0mm per 90 degree but some subsections
result in more mm. There's still exactly 2000 teeth per 90 degree
rotation and 8000 teeth per 360 degree.
The same principle applies. The maths just become a bit more
complicated and you may need infinite series to get the exact result.
http://en.wikipedia.org/wiki/File:Parametric_ellipse.gif
that the speed of travel of the point on the circle is constant but
the speed of travel of the point on the elipse varies, sometime being
faster and sometimes slower. This is also what happens would happen
to a chain on an elipse.
http://www.noncircularchainring.be/pdf/Biomechanical%20study%20chainrings%20-%20release%202.pdf
The purely mechanical section of this paper is irrefutable. They
compute the angular velocity of various chainrig using AutoCAD and
MATLAB. The biomechanical section where they produce an equation to
model the human is where there is room for interpretation.
Some manufacturers also have literature on their site on the subject.
Yannick
(sorry about the long message but this is not pantomine, this is
science and facts)

This makes some sense to me. What you are saying is that a non-round
chainring will pull more, or fewer, chain links/teeth through a
particular section of the pedalling circle, effectively changing the
gearing during the time - more chain pulled is the same as having a
stiffer, bigger gear, and less chain pulled is the same as having a
smaller gear.

Yes

Post by Steve Freides
So the net effect, you're saying, is to give an easier to pedal, smaller
gear where we we are weakest in the pedalling cicle, and a stiffer gear
where we have more strength - is that what you're saying?

Yes
(depending on the specific shape of the rig and the specific
alignment.)

It sounds good in theory but the theory cannot be proven
because it's wrong. The ONLY thing that determines
gearing in number of teeth. Not changing the number
of teeth (as in upshifting and downshifting to change
the number of teeth) will cause the gear ratio to remain
the same. Any illusion that an elliptical chainring pulling
more or less chain teeth at any given time is an illusion.
It's not the diameter of the chainring at the ingress
or egress of the chain from the chainring time that matters
but rather the number of teeth that will maintain the
same gear ratio no matter the shape.

An ellipse with 53 teeth is no different than a circle with
53 teeth when it comes to gear ratio. There is no way
to get some increased or reduced gear ratio without
changing the number of teeth.

[atriage]

Post by Sir Gregory Hall, Esq·

Post by none) (Yannick Tremblay

Post by Steve Freides

Post by none) (Yannick Tremblay
So basically, if we turn the pedals 22.5 degree (along the circular
movement of the pedal), the amount the chain will be pulled depends on
the position of the square.
0 to 22.5 deg => 41.4mm =~ 414 teeth
22.5 to 45 deg => 58.6mm =~ 586 teeth
45 to 67.5 => 58.6mm =~ 586 teeth
67.5 to 90 => 41.4mm =~ 414 teeth
-11.25 to 11.25 deg => 39.8mm =~ 398 teeth
11.25 to 33.75 deg => 46.9mm =~ 469 teeth
33.75 to 56.25 => 66.4mm =~ 664 teeth
56.25 to 78.75 => 46.9mm =~ 469 teeth
There is still exactly 200.0mm per 90 degree but some subsections
result in more mm. There's still exactly 2000 teeth per 90 degree
rotation and 8000 teeth per 360 degree.
The same principle applies. The maths just become a bit more
complicated and you may need infinite series to get the exact result.
http://en.wikipedia.org/wiki/File:Parametric_ellipse.gif
that the speed of travel of the point on the circle is constant but
the speed of travel of the point on the elipse varies, sometime being
faster and sometimes slower. This is also what happens would happen
to a chain on an elipse.
http://www.noncircularchainring.be/pdf/Biomechanical%20study%20chainrings%20-%20release%202.pdf
The purely mechanical section of this paper is irrefutable. They
compute the angular velocity of various chainrig using AutoCAD and
MATLAB. The biomechanical section where they produce an equation to
model the human is where there is room for interpretation.
Some manufacturers also have literature on their site on the subject.
Yannick
(sorry about the long message but this is not pantomine, this is
science and facts)

This makes some sense to me. What you are saying is that a non-round
chainring will pull more, or fewer, chain links/teeth through a
particular section of the pedalling circle, effectively changing the
gearing during the time - more chain pulled is the same as having a
stiffer, bigger gear, and less chain pulled is the same as having a
smaller gear.

Yes

Post by Steve Freides
So the net effect, you're saying, is to give an easier to pedal, smaller
gear where we we are weakest in the pedalling cicle, and a stiffer gear
where we have more strength - is that what you're saying?

Yes
(depending on the specific shape of the rig and the specific
alignment.)

It sounds good in theory but the theory cannot be proven
because it's wrong. The ONLY thing that determines
gearing in number of teeth. Not changing the number
of teeth (as in upshifting and downshifting to change
the number of teeth) will cause the gear ratio to remain
the same. Any illusion that an elliptical chainring pulling
more or less chain teeth at any given time is an illusion.
It's not the diameter of the chainring at the ingress
or egress of the chain from the chainring time that matters
but rather the number of teeth that will maintain the
same gear ratio no matter the shape.
An ellipse with 53 teeth is no different than a circle with
53 teeth when it comes to gear ratio. There is no way
to get some increased or reduced gear ratio without
changing the number of teeth.

My God you're stupid.

[Sir Gregory Hall, Esq·]

Post by atriage

Post by Sir Gregory Hall, Esq·

Post by none) (Yannick Tremblay

Post by Steve Freides

Post by none) (Yannick Tremblay
So basically, if we turn the pedals 22.5 degree (along the circular
movement of the pedal), the amount the chain will be pulled depends on
the position of the square.
0 to 22.5 deg => 41.4mm =~ 414 teeth
22.5 to 45 deg => 58.6mm =~ 586 teeth
45 to 67.5 => 58.6mm =~ 586 teeth
67.5 to 90 => 41.4mm =~ 414 teeth
-11.25 to 11.25 deg => 39.8mm =~ 398 teeth
11.25 to 33.75 deg => 46.9mm =~ 469 teeth
33.75 to 56.25 => 66.4mm =~ 664 teeth
56.25 to 78.75 => 46.9mm =~ 469 teeth
There is still exactly 200.0mm per 90 degree but some subsections
result in more mm. There's still exactly 2000 teeth per 90 degree
rotation and 8000 teeth per 360 degree.
The same principle applies. The maths just become a bit more
complicated and you may need infinite series to get the exact result.
http://en.wikipedia.org/wiki/File:Parametric_ellipse.gif
that the speed of travel of the point on the circle is constant but
the speed of travel of the point on the elipse varies, sometime being
faster and sometimes slower. This is also what happens would happen
to a chain on an elipse.
http://www.noncircularchainring.be/pdf/Biomechanical%20study%20chainrings%20-%20release%202.pdf
The purely mechanical section of this paper is irrefutable. They
compute the angular velocity of various chainrig using AutoCAD and
MATLAB. The biomechanical section where they produce an equation to
model the human is where there is room for interpretation.
Some manufacturers also have literature on their site on the subject.
Yannick
(sorry about the long message but this is not pantomine, this is
science and facts)

This makes some sense to me. What you are saying is that a non-round
chainring will pull more, or fewer, chain links/teeth through a
particular section of the pedalling circle, effectively changing the
gearing during the time - more chain pulled is the same as having a
stiffer, bigger gear, and less chain pulled is the same as having a
smaller gear.

Yes

Post by Steve Freides
So the net effect, you're saying, is to give an easier to pedal, smaller
gear where we we are weakest in the pedalling cicle, and a stiffer gear
where we have more strength - is that what you're saying?

Yes
(depending on the specific shape of the rig and the specific
alignment.)

It sounds good in theory but the theory cannot be proven
because it's wrong. The ONLY thing that determines
gearing in number of teeth. Not changing the number
of teeth (as in upshifting and downshifting to change
the number of teeth) will cause the gear ratio to remain
the same. Any illusion that an elliptical chainring pulling
more or less chain teeth at any given time is an illusion.
It's not the diameter of the chainring at the ingress
or egress of the chain from the chainring time that matters
but rather the number of teeth that will maintain the
same gear ratio no matter the shape.
An ellipse with 53 teeth is no different than a circle with
53 teeth when it comes to gear ratio. There is no way
to get some increased or reduced gear ratio without
changing the number of teeth.

My God you're stupid.

I bet this *stupid* guy can kick your ass on a bike.

[atriage]

Post by Sir Gregory Hall, Esq·

Post by atriage

Post by Sir Gregory Hall, Esq·

Post by none) (Yannick Tremblay

Post by Steve Freides

Post by none) (Yannick Tremblay
So basically, if we turn the pedals 22.5 degree (along the circular
movement of the pedal), the amount the chain will be pulled depends on
the position of the square.
0 to 22.5 deg => 41.4mm =~ 414 teeth
22.5 to 45 deg => 58.6mm =~ 586 teeth
45 to 67.5 => 58.6mm =~ 586 teeth
67.5 to 90 => 41.4mm =~ 414 teeth
-11.25 to 11.25 deg => 39.8mm =~ 398 teeth
11.25 to 33.75 deg => 46.9mm =~ 469 teeth
33.75 to 56.25 => 66.4mm =~ 664 teeth
56.25 to 78.75 => 46.9mm =~ 469 teeth
There is still exactly 200.0mm per 90 degree but some subsections
result in more mm. There's still exactly 2000 teeth per 90 degree
rotation and 8000 teeth per 360 degree.
The same principle applies. The maths just become a bit more
complicated and you may need infinite series to get the exact result.
http://en.wikipedia.org/wiki/File:Parametric_ellipse.gif
that the speed of travel of the point on the circle is constant but
the speed of travel of the point on the elipse varies, sometime being
faster and sometimes slower. This is also what happens would happen
to a chain on an elipse.
http://www.noncircularchainring.be/pdf/Biomechanical%20study%20chainrings%20-%20release%202.pdf
The purely mechanical section of this paper is irrefutable. They
compute the angular velocity of various chainrig using AutoCAD and
MATLAB. The biomechanical section where they produce an equation to
model the human is where there is room for interpretation.
Some manufacturers also have literature on their site on the subject.
Yannick
(sorry about the long message but this is not pantomine, this is
science and facts)

This makes some sense to me. What you are saying is that a non-round
chainring will pull more, or fewer, chain links/teeth through a
particular section of the pedalling circle, effectively changing the
gearing during the time - more chain pulled is the same as having a
stiffer, bigger gear, and less chain pulled is the same as having a
smaller gear.

Yes

Post by Steve Freides
So the net effect, you're saying, is to give an easier to pedal, smaller
gear where we we are weakest in the pedalling cicle, and a stiffer gear
where we have more strength - is that what you're saying?

Yes
(depending on the specific shape of the rig and the specific
alignment.)

It sounds good in theory but the theory cannot be proven
because it's wrong. The ONLY thing that determines
gearing in number of teeth. Not changing the number
of teeth (as in upshifting and downshifting to change
the number of teeth) will cause the gear ratio to remain
the same. Any illusion that an elliptical chainring pulling
more or less chain teeth at any given time is an illusion.
It's not the diameter of the chainring at the ingress
or egress of the chain from the chainring time that matters
but rather the number of teeth that will maintain the
same gear ratio no matter the shape.
An ellipse with 53 teeth is no different than a circle with
53 teeth when it comes to gear ratio. There is no way
to get some increased or reduced gear ratio without
changing the number of teeth.

My God you're stupid.

I bet this *stupid* guy can kick your ass on a bike.

You sure could if you're as good as you *imagine* you are. What you
really are however is an aging deluded twat.

[Mower Man]

Post by atriage

Post by Sir Gregory Hall, Esq·

Post by none) (Yannick Tremblay

Post by Steve Freides

Post by none) (Yannick Tremblay
So basically, if we turn the pedals 22.5 degree (along the circular
movement of the pedal), the amount the chain will be pulled depends on
the position of the square.
0 to 22.5 deg => 41.4mm =~ 414 teeth
22.5 to 45 deg => 58.6mm =~ 586 teeth
45 to 67.5 => 58.6mm =~ 586 teeth
67.5 to 90 => 41.4mm =~ 414 teeth
-11.25 to 11.25 deg => 39.8mm =~ 398 teeth
11.25 to 33.75 deg => 46.9mm =~ 469 teeth
33.75 to 56.25 => 66.4mm =~ 664 teeth
56.25 to 78.75 => 46.9mm =~ 469 teeth
There is still exactly 200.0mm per 90 degree but some subsections
result in more mm. There's still exactly 2000 teeth per 90 degree
rotation and 8000 teeth per 360 degree.
The same principle applies. The maths just become a bit more
complicated and you may need infinite series to get the exact result.
http://en.wikipedia.org/wiki/File:Parametric_ellipse.gif
that the speed of travel of the point on the circle is constant but
the speed of travel of the point on the elipse varies, sometime being
faster and sometimes slower. This is also what happens would happen
to a chain on an elipse.
http://www.noncircularchainring.be/pdf/Biomechanical%20study%20chainrings%20-%20release%202.pdf
The purely mechanical section of this paper is irrefutable. They
compute the angular velocity of various chainrig using AutoCAD and
MATLAB. The biomechanical section where they produce an equation to
model the human is where there is room for interpretation.
Some manufacturers also have literature on their site on the subject.
Yannick
(sorry about the long message but this is not pantomine, this is
science and facts)

This makes some sense to me. What you are saying is that a non-round
chainring will pull more, or fewer, chain links/teeth through a
particular section of the pedalling circle, effectively changing the
gearing during the time - more chain pulled is the same as having a
stiffer, bigger gear, and less chain pulled is the same as having a
smaller gear.

Yes

Post by Steve Freides
So the net effect, you're saying, is to give an easier to pedal, smaller
gear where we we are weakest in the pedalling cicle, and a stiffer gear
where we have more strength - is that what you're saying?

Yes
(depending on the specific shape of the rig and the specific
alignment.)

It sounds good in theory but the theory cannot be proven
because it's wrong. The ONLY thing that determines
gearing in number of teeth. Not changing the number
of teeth (as in upshifting and downshifting to change
the number of teeth) will cause the gear ratio to remain
the same. Any illusion that an elliptical chainring pulling
more or less chain teeth at any given time is an illusion.
It's not the diameter of the chainring at the ingress
or egress of the chain from the chainring time that matters
but rather the number of teeth that will maintain the
same gear ratio no matter the shape.
An ellipse with 53 teeth is no different than a circle with
53 teeth when it comes to gear ratio. There is no way
to get some increased or reduced gear ratio without
changing the number of teeth.

My God you're stupid.

+1

[atriage]

Post by atriage

Post by Sir Gregory Hall, Esq·

Post by none) (Yannick Tremblay

Post by Steve Freides

Post by none) (Yannick Tremblay
So basically, if we turn the pedals 22.5 degree (along the circular
movement of the pedal), the amount the chain will be pulled depends on
the position of the square.
0 to 22.5 deg => 41.4mm =~ 414 teeth
22.5 to 45 deg => 58.6mm =~ 586 teeth
45 to 67.5 => 58.6mm =~ 586 teeth
67.5 to 90 => 41.4mm =~ 414 teeth
-11.25 to 11.25 deg => 39.8mm =~ 398 teeth
11.25 to 33.75 deg => 46.9mm =~ 469 teeth
33.75 to 56.25 => 66.4mm =~ 664 teeth
56.25 to 78.75 => 46.9mm =~ 469 teeth
There is still exactly 200.0mm per 90 degree but some subsections
result in more mm. There's still exactly 2000 teeth per 90 degree
rotation and 8000 teeth per 360 degree.
The same principle applies. The maths just become a bit more
complicated and you may need infinite series to get the exact result.
http://en.wikipedia.org/wiki/File:Parametric_ellipse.gif
that the speed of travel of the point on the circle is constant but
the speed of travel of the point on the elipse varies, sometime being
faster and sometimes slower. This is also what happens would happen
to a chain on an elipse.
http://www.noncircularchainring.be/pdf/Biomechanical%20study%20chainrings%20-%20release%202.pdf
The purely mechanical section of this paper is irrefutable. They
compute the angular velocity of various chainrig using AutoCAD and
MATLAB. The biomechanical section where they produce an equation to
model the human is where there is room for interpretation.
Some manufacturers also have literature on their site on the subject.
Yannick
(sorry about the long message but this is not pantomine, this is
science and facts)

This makes some sense to me. What you are saying is that a non-round
chainring will pull more, or fewer, chain links/teeth through a
particular section of the pedalling circle, effectively changing the
gearing during the time - more chain pulled is the same as having a
stiffer, bigger gear, and less chain pulled is the same as having a
smaller gear.

Yes

Post by Steve Freides
So the net effect, you're saying, is to give an easier to pedal, smaller
gear where we we are weakest in the pedalling cicle, and a stiffer gear
where we have more strength - is that what you're saying?

Yes
(depending on the specific shape of the rig and the specific
alignment.)

It sounds good in theory but the theory cannot be proven
because it's wrong. The ONLY thing that determines
gearing in number of teeth. Not changing the number
of teeth (as in upshifting and downshifting to change
the number of teeth) will cause the gear ratio to remain
the same. Any illusion that an elliptical chainring pulling
more or less chain teeth at any given time is an illusion.
It's not the diameter of the chainring at the ingress
or egress of the chain from the chainring time that matters
but rather the number of teeth that will maintain the
same gear ratio no matter the shape.
An ellipse with 53 teeth is no different than a circle with
53 teeth when it comes to gear ratio. There is no way
to get some increased or reduced gear ratio without
changing the number of teeth.

My God you're stupid.

+1

At first I thought he was a troll but it seems he really believes the
shit he posts.

[Phil H]

Post by atriage

Post by atriage

Post by Sir Gregory Hall, Esq·

Post by none) (Yannick Tremblay

Post by Steve Freides

Post by none) (Yannick Tremblay
So basically, if we turn the pedals 22.5 degree (along the circular
movement of the pedal), the amount the chain will be pulled
depends on
the position of the square.
0 to 22.5 deg => 41.4mm =~ 414 teeth
22.5 to 45 deg => 58.6mm =~ 586 teeth
45 to 67.5 => 58.6mm =~ 586 teeth
67.5 to 90 => 41.4mm =~ 414 teeth
-11.25 to 11.25 deg => 39.8mm =~ 398 teeth
11.25 to 33.75 deg => 46.9mm =~ 469 teeth
33.75 to 56.25 => 66.4mm =~ 664 teeth
56.25 to 78.75 => 46.9mm =~ 469 teeth
There is still exactly 200.0mm per 90 degree but some subsections
result in more mm. There's still exactly 2000 teeth per 90 degree
rotation and 8000 teeth per 360 degree.
The same principle applies. The maths just become a bit more
complicated and you may need infinite series to get the exact result.
http://en.wikipedia.org/wiki/File:Parametric_ellipse.gif
that the speed of travel of the point on the circle is constant but
the speed of travel of the point on the elipse varies, sometime being
faster and sometimes slower. This is also what happens would happen
to a chain on an elipse.
http://www.noncircularchainring.be/pdf/Biomechanical%20study%20chainrings%20-%20release%202.pdf
The purely mechanical section of this paper is irrefutable. They
compute the angular velocity of various chainrig using AutoCAD and
MATLAB. The biomechanical section where they produce an equation to
model the human is where there is room for interpretation.
Some manufacturers also have literature on their site on the subject.
Yannick
(sorry about the long message but this is not pantomine, this is
science and facts)

This makes some sense to me. What you are saying is that a non-round
chainring will pull more, or fewer, chain links/teeth through a
particular section of the pedalling circle, effectively changing the
gearing during the time - more chain pulled is the same as having a
stiffer, bigger gear, and less chain pulled is the same as having a
smaller gear.

Yes

Post by Steve Freides
So the net effect, you're saying, is to give an easier to pedal,
smaller
gear where we we are weakest in the pedalling cicle, and a stiffer
gear
where we have more strength - is that what you're saying?

Yes
(depending on the specific shape of the rig and the specific
alignment.)

It sounds good in theory but the theory cannot be proven
because it's wrong. The ONLY thing that determines
gearing in number of teeth. Not changing the number
of teeth (as in upshifting and downshifting to change
the number of teeth) will cause the gear ratio to remain
the same. Any illusion that an elliptical chainring pulling
more or less chain teeth at any given time is an illusion.
It's not the diameter of the chainring at the ingress
or egress of the chain from the chainring time that matters
but rather the number of teeth that will maintain the
same gear ratio no matter the shape.
An ellipse with 53 teeth is no different than a circle with
53 teeth when it comes to gear ratio. There is no way
to get some increased or reduced gear ratio without
changing the number of teeth.

My God you're stupid.

+1

At first I thought he was a troll but it seems he really believes the
shit he posts.

You and none may have gone past the point of invoking the following ground rule.........."when you argue with a fool, chances are they are doing the same thing". Your bail out point may vary but its way passed mine.
Phil H

[Davey Crockett]

Phil H a écrit profondement:

| > At first I thought he was a troll but it seems he really believes the
| >
| > shit he posts.
| You and none may have gone past the point of invoking the following
| ground rule.........."when you argue with a fool, chances are they are
| doing the same thing". Your bail out point may vary but its way passed
| mine.
| Phil H

Loading Image...


And trim the garbage out too.

[atriage]

Post by Davey Crockett
| > At first I thought he was a troll but it seems he really believes the
| >
| > shit he posts.
| You and none may have gone past the point of invoking the following
| ground rule.........."when you argue with a fool, chances are they are
| doing the same thing". Your bail out point may vary but its way passed
| mine.
| Phil H
http://azurservers.com/rbr/aoi.jpg
And trim the garbage out too.

You wanna trim you trim, whether or not I do will depend entirely on
whether I can be arsed to at that particular moment. You have no input
on the decision.

[atriage]

Post by Phil H

Post by atriage
At first I thought he was a troll but it seems he really believes the
shit he posts.

Your bail out point may vary but its way passed mine.

Yeah mine does vary, it's my civic duty to make sure twats like Greg are
kept abreast of the current situation regarding their status. You may
also note that there is virtually no traffic actually concerned with
racing here anymore so ant post is gonna be OT. RBR has become a chat
room with a vaguely cycle oriented theme which I find entertaining
enough. Entertainment being the only actual point of usenet.

[none) (Yannick Tremblay]

Post by Sir Gregory Hall, Esq·

Post by none) (Yannick Tremblay

Post by Steve Freides

Post by none) (Yannick Tremblay
So basically, if we turn the pedals 22.5 degree (along the circular
movement of the pedal), the amount the chain will be pulled depends on
the position of the square.
0 to 22.5 deg => 41.4mm =~ 414 teeth
22.5 to 45 deg => 58.6mm =~ 586 teeth
45 to 67.5 => 58.6mm =~ 586 teeth
67.5 to 90 => 41.4mm =~ 414 teeth
-11.25 to 11.25 deg => 39.8mm =~ 398 teeth
11.25 to 33.75 deg => 46.9mm =~ 469 teeth
33.75 to 56.25 => 66.4mm =~ 664 teeth
56.25 to 78.75 => 46.9mm =~ 469 teeth
There is still exactly 200.0mm per 90 degree but some subsections
result in more mm. There's still exactly 2000 teeth per 90 degree
rotation and 8000 teeth per 360 degree.
The same principle applies. The maths just become a bit more
complicated and you may need infinite series to get the exact result.
http://en.wikipedia.org/wiki/File:Parametric_ellipse.gif
that the speed of travel of the point on the circle is constant but
the speed of travel of the point on the elipse varies, sometime being
faster and sometimes slower. This is also what happens would happen
to a chain on an elipse.
http://www.noncircularchainring.be/pdf/Biomechanical%20study%20chainrings%20-%20release%202.pdf
The purely mechanical section of this paper is irrefutable. They
compute the angular velocity of various chainrig using AutoCAD and
MATLAB. The biomechanical section where they produce an equation to
model the human is where there is room for interpretation.
Some manufacturers also have literature on their site on the subject.
Yannick
(sorry about the long message but this is not pantomine, this is
science and facts)

This makes some sense to me. What you are saying is that a non-round
chainring will pull more, or fewer, chain links/teeth through a
particular section of the pedalling circle, effectively changing the
gearing during the time - more chain pulled is the same as having a
stiffer, bigger gear, and less chain pulled is the same as having a
smaller gear.

Yes

Post by Steve Freides
So the net effect, you're saying, is to give an easier to pedal, smaller
gear where we we are weakest in the pedalling cicle, and a stiffer gear
where we have more strength - is that what you're saying?

Yes
(depending on the specific shape of the rig and the specific
alignment.)

It sounds good in theory but the theory cannot be proven
because it's wrong. The ONLY thing that determines
gearing in number of teeth. Not changing the number
of teeth (as in upshifting and downshifting to change
the number of teeth) will cause the gear ratio to remain
the same. Any illusion that an elliptical chainring pulling
more or less chain teeth at any given time is an illusion.
It's not the diameter of the chainring at the ingress
or egress of the chain from the chainring time that matters
but rather the number of teeth that will maintain the
same gear ratio no matter the shape.
An ellipse with 53 teeth is no different than a circle with
53 teeth when it comes to gear ratio. There is no way
to get some increased or reduced gear ratio without
changing the number of teeth.

I am sorry. I've gone through the long explanation for the benefit of
peoples that were confused but wanted to learn. You are welcome to
close your eyes, put your fingers in your ear and yell "NO! NO! NO!"
forever.

Your anti-eliptical chain rig position would be a lot more credible if
you'd accept the hard proven facts that there is a mechanical difference in
the pedal-front rig-chain-cassette-whell assembly but that this
mechanical difference does lead to a biomechanical advantage once you
add the cyclist into the equation.

This last part has certainly not been proven despite some attempts at
modelling it and some experimental studies (some of them sponsored by
manufacturers).

Unfortunately your current position is like claiming that the Earth is
flat.

Regards
Yan

[Mower Man]

Post by Steve Freides

Post by none) (Yannick Tremblay

Post by Steve Freides

Post by Mower Man
Isn't it the point that elliptical chain rings actually vary the
gear ratio? Forget the number of teeth, they're only there 'cos a
chain is used. Think of diameter. Variable diameter. Honest. Think
drive belt? Big pulley vs small pulley?

But big pulley versus small pulley, first of all, means something
different for belt drive than for one with teeth. If one pedal
revolution gets you 39 teeth spaced evenly apart, what's the
difference what the shape is? For a belt driven system, a change in
shape could at least mean a change in circumference.

For 1 complete revolution, there is no difference. Absolutely correct.
However what about 1/4 of a revolution or 1/8 of a revolution? Then
the diameter of the "big pulley" does differs.
Yan

You misread what I wrote. I don't assume that a change in circumference
matters, either - you could accomplish the same thing with a larger or
smaller, but still round, pulley.
The reason tests cannot confirm that this idea works is simple - it
doesn't. Neither the rear wheel nor your legs care about the shape of
the chainring. When you're pulling one tooth's worth of chain, that's
what you're doing, period.
-S-

I think you've failed to understand my post? Disregard the bloody chain,
it's totally irrelevant. Think of the diameter of the chainring. An
elliptical ring's diameter varies. It's that simple. If the chainring
was the diameter of it's smallest point, gearing would be lower.
Conversely, at it's largest point, higher.

The chain is just a way (one way) of joining two things in a non slip
way. Bet there's an internal combustion engine that uses this stuff to
vary camshaft timing. (Research on way?)

As for your remarks about "change in circumference", that's exactly what
an elliptical ring does. Changes gearing with every revolution.

[Sir Gregory Hall, Esq·]

Post by none) (Yannick Tremblay

Post by Steve Freides

Post by Mower Man
Isn't it the point that elliptical chain rings actually vary the gear
ratio? Forget the number of teeth, they're only there 'cos a chain is
used. Think of diameter. Variable diameter. Honest. Think drive belt?
Big pulley vs small pulley?

But big pulley versus small pulley, first of all, means something
different for belt drive than for one with teeth. If one pedal
revolution gets you 39 teeth spaced evenly apart, what's the difference
what the shape is? For a belt driven system, a change in shape could at
least mean a change in circumference.

For 1 complete revolution, there is no difference. Absolutely correct.
However what about 1/4 of a revolution or 1/8 of a revolution? Then
the diameter of the "big pulley" does differs.

True, but *overall* diameter doesn't change as the number
of teeth remains the same. So, the gear ratio remains the
same. And, as long as the chainring radius is no greater than
that of the crank arm there isn't even any leverage difference
as if often the (erroneous) claim, due to the fact that it's
the length of the crank arms that determines the lever arm.

[none) (Yannick Tremblay]

Post by Sir Gregory Hall, Esq·

Post by none) (Yannick Tremblay

Post by Steve Freides

Post by Mower Man
Isn't it the point that elliptical chain rings actually vary the gear
ratio? Forget the number of teeth, they're only there 'cos a chain is
used. Think of diameter. Variable diameter. Honest. Think drive belt?
Big pulley vs small pulley?

But big pulley versus small pulley, first of all, means something
different for belt drive than for one with teeth. If one pedal
revolution gets you 39 teeth spaced evenly apart, what's the difference
what the shape is? For a belt driven system, a change in shape could at
least mean a change in circumference.

For 1 complete revolution, there is no difference. Absolutely correct.
However what about 1/4 of a revolution or 1/8 of a revolution? Then
the diameter of the "big pulley" does differs.

True, but *overall* diameter doesn't change as the number
of teeth remains the same. So, the gear ratio remains the
same. And, as long as the chainring radius is no greater than
that of the crank arm there isn't even any leverage difference
as if often the (erroneous) claim, due to the fact that it's
the length of the crank arms that determines the lever arm.

Please, this is pure mathematics and mechanics.

The "active" "current" diameter of the front rig changes dynamically
during a rotation which means that the current amount of rotation
of the pedal that is needs to achieve some specific rotation of
the rear wheel with the pedal-crank-rig-chain-cog-wheel assembly
changes dynamically. In average over 360 degree it is the same but
instantaneously it differs.

The problem and complexity occurs when you start introducing a bloody
human in the equation and these pesky things are pretty much impossible
to model mathematically and are notoriously irregular between
individuals.

Serously, by all mean disagree that it has any benefits to humans (I
am certainly not convinced either) but lets not disagree on
mathematics.

Yan

[Mower Man]

Post by none) (Yannick Tremblay

Post by Sir Gregory Hall, Esq·

Post by none) (Yannick Tremblay

Post by Steve Freides

Post by Mower Man
Isn't it the point that elliptical chain rings actually vary the gear
ratio? Forget the number of teeth, they're only there 'cos a chain is
used. Think of diameter. Variable diameter. Honest. Think drive belt?
Big pulley vs small pulley?

But big pulley versus small pulley, first of all, means something
different for belt drive than for one with teeth. If one pedal
revolution gets you 39 teeth spaced evenly apart, what's the difference
what the shape is? For a belt driven system, a change in shape could at
least mean a change in circumference.

For 1 complete revolution, there is no difference. Absolutely correct.
However what about 1/4 of a revolution or 1/8 of a revolution? Then
the diameter of the "big pulley" does differs.

True, but *overall* diameter doesn't change as the number
of teeth remains the same. So, the gear ratio remains the
same. And, as long as the chainring radius is no greater than
that of the crank arm there isn't even any leverage difference
as if often the (erroneous) claim, due to the fact that it's
the length of the crank arms that determines the lever arm.

Please, this is pure mathematics and mechanics.
The "active" "current" diameter of the front rig changes dynamically
during a rotation which means that the current amount of rotation
of the pedal that is needs to achieve some specific rotation of
the rear wheel with the pedal-crank-rig-chain-cog-wheel assembly
changes dynamically. In average over 360 degree it is the same but
instantaneously it differs.
The problem and complexity occurs when you start introducing a bloody
human in the equation and these pesky things are pretty much impossible
to model mathematically and are notoriously irregular between
individuals.
Serously, by all mean disagree that it has any benefits to humans (I
am certainly not convinced either) but lets not disagree on
mathematics.
Yan

Congratulations. "Instantaneously". Very nearly the right word.

"Progressively" and "variably" would have been even better.

I think that there are benefits as we humans are:

a) good at stamping down

b) not too bad at pulling up on the cleats

c) not very good at pushing over TDC or BDC.

d) ...er, that's it.

[Mower Man]

Post by none) (Yannick Tremblay

Post by Steve Freides

Post by Mower Man
Isn't it the point that elliptical chain rings actually vary the gear
ratio? Forget the number of teeth, they're only there 'cos a chain is
used. Think of diameter. Variable diameter. Honest. Think drive belt?
Big pulley vs small pulley?

But big pulley versus small pulley, first of all, means something
different for belt drive than for one with teeth. If one pedal
revolution gets you 39 teeth spaced evenly apart, what's the difference
what the shape is? For a belt driven system, a change in shape could at
least mean a change in circumference.

For 1 complete revolution, there is no difference. Absolutely correct.
However what about 1/4 of a revolution or 1/8 of a revolution? Then
the diameter of the "big pulley" does differs.
Yan

Spot on. That's how it works.

[Mower Man]

Post by Steve Freides

Post by Mower Man

Post by Steve Freides

Post by Davey Crockett

Post by Sir Gregory Hall, Esq·
Elliptical chainrings are a GIMMICK. Why?
Because gearing depends upon the number of teeth on
the chainring and the number of teeth on the cassette.
When spinning the crankshaft it doesn't matter one iota
what shape the chainring is. All that matters is the
relationship between the number of teeth on the
chainring and the number of teeth on the particular
cassette ring.
Any idiot who thinks otherwise is just that, an idiot!

The original concept, way back, was that the eliptical shape
allowed one to transmit the same, or reasoably the same, power to
the drive train whether the cranks were at TDC, BDC or any other
aspect.
(TDC=Top Dead Center)

Wouldn't it make more sense, then for the pedaling circle to be
elliptical, rather than the chainrings? I'm not quite sure how one
would achieve that end, but Sir Gregory Hall seems to have a point
here - if you're still pedaling circles, it doesn't matter how the
chainrings are shaped.

Post by Davey Crockett
Davey remembers Jeff Bernard proudly sporting the "BioPace" decal
on his regular (round) chainring. He didn't believe the Shimano BS
either apparently.

Ah, yes, I did try BioPace back in the day. NB: they, nor any other
non-round chainrings, are terribly useful on a fixed gear.
-S-

Isn't it the point that elliptical chain rings actually vary the gear
ratio? Forget the number of teeth, they're only there 'cos a chain is
used. Think of diameter. Variable diameter. Honest. Think drive belt?
Big pulley vs small pulley?

But big pulley versus small pulley, first of all, means something
different for belt drive than for one with teeth. If one pedal
revolution gets you 39 teeth spaced evenly apart, what's the difference
what the shape is? For a belt driven system, a change in shape could at
least mean a change in circumference.
-S-

See next post - totally correct!