Elliptical Chainrings

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-

On Wednesday, July 10, 2013 9:33:17 AM UTC-7, Steve Freides wrote:
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


better.



-S-

"Steve Freides" wrote in message
...
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!

--
Sir Gregory

" 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.

--
Davey Crockett
Fly your Flag
http://inconnu.freeshell.org/rbr/portugal-flag.gif
**** the New World Order.

Davey Crockett wrote:
" 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)

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.

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-

On 18/07/2013 9:26 PM, Steve Freides wrote:
Davey Crockett wrote:
" 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)

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.

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?
--
Chris

'Fashion is a form of ugliness so intolerable that we have to alter it
every six months.'

(Oscar Wilde.)

Mower Man wrote:
On 18/07/2013 9:26 PM, Steve Freides wrote:
Davey Crockett wrote:
" 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)

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.

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-

In article ,
Steve Freides wrote:
Mower Man wrote:

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

Yannick Tremblay yatremblay@bel1lin202.(none) wrote:
In article ,
Steve Freides wrote:
Mower Man wrote:

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?

none (Yannick Tremblay) wrote:
In article ,
Steve Freides wrote:
Mower Man wrote:

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-