Using elliptic chain wheel.

Quoted message said:

I'm going to make elliptic chain wheel for my bike.
I'll take any sugestions and advises.

See: http://sheldonbrown.com/biopace

Sheldon "Point Symmetrical Egg Curve" Brown
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Sheldon Brown said:

See: http://sheldonbrown.com/biopace

Sheldon "Point Symmetrical Egg Curve" Brown

Sorry; I have to disagree with you based upon my own experiences with
Biopace. I never had any knee troubles at all until I used Biopace
chain rings. Replaced them with round chain rings and have been
pedalling happily and painlessly ever since.

Your mileage may vary.

Greg

In article <[email hidden]>,
[email hidden] says...

Quoted message said:

I'm going to make elliptic chain wheel for my bike.
I'll take any sugestions and advises.

Why? What do you suppose you will gain by doing this? If you really want, I'm
sure you could find someone selling dirt cheap, or giving away, biopace
chainrings.
--------------
Alex

"Alex Rodriguez" wrote: (clip)I'm sure you could find someone selling dirt
cheap, or giving away, biopace chainrings.
^^^^^^^^^^^^^^^^
I used to have a 27 speed mountain bike with elliptical chainrings. I can
testify that they do work, and they are NOT the same as biopace. First of
all, Biopace are not elliptical--they are some weird shape which was
designed to make your foot match the speed of a walking foot. I got this
information from a very good bike mechanic who worked for Shimano at the
time Biopace was being developed. He left Shimano and produced elliptical
rings which operate on a totally different theory. To wit:

As your pedal passes through the top of the rotation, you have the least
pedalling strength. So he positions the ellipse to put you in a TALLER
gear, to get you through that position faster. As the pedal comes around to
the front of the circle, you have the maximum leverage and muscular
advantage, so the ellipse is positioned to LOWER your gearing, so you spend
more time in the part of the stroke where you are strong. This really shows
up when you are climbing a steep hill near the limit of your ability. In
effect, it gives you gearing which is lower than the tooth-count ratio would
indicate. He also made the claim that this system has less tendency to
produce wheel spin on loose surfaces. I don't remember the explanation, but
I do recall that it seemed to work for me.

Biopace can not be converted into an approximation of this elliptical setup,
because you can't turn a chainring with five bolts 90 degrees.

Alex Rodriguez said:

In article <[email hidden]>,
[email hidden] says...

Quoted message said:

I'm going to make elliptic chain wheel for my bike.
I'll take any sugestions and advises.

Why? What do you suppose you will gain by doing this? If you really want, I'm
sure you could find someone selling dirt cheap, or giving away, biopace
chainrings.

Possibly, but they certainly wouldn't be elliptical since the biopace
rings are a completely different shape. Various makers have produced
true elliptical chain wheels in the past, including Roger Durham, and
you may be able to find some used ones. One issue was incompatibility
with front derailleurs; friends who used them generally used very wide
range rear cog sets and sometimes had a bailout granny ring that they
shifted into by hand (i.e. lifting the chain and dropping it onto the
small ring).

-----BEGIN PGP SIGNED MESSAGE-----

In article <[email hidden]>,

Peter said:

Alex Rodriguez said:

In article <[email hidden]>,
[email hidden] says...

Quoted message said:

I'm going to make elliptic chain wheel for my bike.
I'll take any sugestions and advises.

Why? What do you suppose you will gain by doing this? If you really want, I'm
sure you could find someone selling dirt cheap, or giving away, biopace
chainrings.

Possibly, but they certainly wouldn't be elliptical since the biopace
rings are a completely different shape. Various makers have produced
true elliptical chain wheels in the past, including Roger Durham, and
you may be able to find some used ones. One issue was incompatibility
with front derailleurs; friends who used them generally used very wide
range rear cog sets and sometimes had a bailout granny ring that they
shifted into by hand (i.e. lifting the chain and dropping it onto the
small ring).

_ There's some company that now makes custom designed chainwheels
for your individual pedaling style. Bobby Julich is racing on
them in the Pro Tour.

http://tinyurl.com/5622c

_ Booker C. Bense

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I made one once using some 1/8" aluminum. I cut a chainring in half,
and made a plate with appropriate holes to secure the two halves of
the chainring. The plate had a circular hole to fit the BCD of the
crankset and was drilled so it could bolt to the crankset.

I used to use it on a recumbent bike where it made pedaling feel a lot
like climbing stairs. I liked it.

Yes,

I agree but difference between non personalized biopace chain rings and
personalized elliptical chain rings is too small about equable
pedalling. And I'm sure that not personalized biopace chain rings are
less efficient.

Best Regards
Gerasim
E-mail: [email hidden]

Thanks Leo,
I agree but difference between non personalized biopace chain rings and
personalized elliptical chain rings is too small about equable
pedalling. And I'm sure that not personalized biopace chain rings are
less efficient.

Best Regards
Gerasim
E-mail: [email hidden]

Yes, I agree with you.
For begining I made computer moving model.
Regards
Gerasim(e-mail: [email hidden])

<[email hidden]> wrote in message
news:[email hidden]...

Quoted message said:

Yes, I agree with you.
For begining I made computer moving model.
Regards
Gerasim(e-mail: [email hidden])

Julich's bike with elliptical rings with O.Symetric Harmony rings:

Excerpt From Cycling News:
http://www.cyclingnews.com/tech/2005/probikes/?id=julich_csc_cervelo
Julich's Soloist is hung with CSC's standard equipment package (we'll get to
that in a moment) but with one dramatic difference. Julich uses French
O.Symetric Harmonic elliptical chainrings, a component selection that we
always get letters about whenever we run a clear side-on pic of Julich's
bike.

To get the obvious question out of the way, this isn't a resurrection of
Shimano's Biopace rings of the 1980s. An elliptical chainring changes the
effective gear ratio as you pedal. Biopace reduced the gear ratio as crank
passed through the horizontal; the O.Symetric Harmonic increases it. The
idea is that the sector of the pedal stroke where the crank is horizontal or
nearly so is where you can push hardest, so it makes sense to increase the
gear at that point, then drop it to get your foot through top and bottom
dead center quickly. It's the same idea as British component maker Chris
Bell's Eggrings and, well, just about every other inventor who has come up
with elliptical chainrings since shortly after chain drives were invented.

However, while the idea has come and gone many times in the last 100 years
or so, it clearly seems to work for Bobby Julich, who has used the
O.Symetric rings to land an Olympic bronze medal, and to contribute to CSC's
team time trial victory in the Tour Méditerranéen.

http://www.osymetric.com/design.htm

Bill

I believe this has already been done by Shimano, as my first bike
approx.13yrs ago had elliptical chainrings, which they called 'biopace'

Regards,
Justin

<[email hidden]> wrote in message
news:[email hidden]...

Quoted message said:

I'm going to make elliptic chain wheel for my bike.
I'll take any sugestions and advises.
Thanks
Gerasim

"Justin Carline" wrote: I believe this has already been done by Shimano, as
my first bike approx.13yrs ago had elliptical chainrings, which they called
'biopace'
^^^^^^^^^^^^^^^^
No. Read my post and Bill's, above.