"BIOPACE" ?? chain rings

My chain used to frequently fall off when I changed rings, or it would not change at all if I backed
off the adjustment. I never noticed any other difference.

Richard "Ben Wight" <[email hidden]> wrote in message "]news:[email hidden]...

Quoted message said:

I think this is what they are called, the out of round (oval) chain rings that from what I
understand allow more torque to be applied for a greater range of the revolution of the
chain wheel.

Is the use of these chain wheels common? Are they used much in racing? If not, why?

Ben Wight

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

Quoted message said:

I think this is what they are called, the out of round (oval) chain rings that from what I
understand allow more torque to be applied for a greater range of the revolution of the
chain wheel.

Is the use of these chain wheels common? Are they used much in racing? If not, why?

A fad, that came and went - and a long time ago now! Shimano eventually came up with their
revolutionary Biopace #2 chainrings... they were *round*.

Commonly used? Not unless you have a 1989 bike. Used in racing? Even less. They make stuff all
difference to your cycling performance, even for the roadies who are after that extra second in a
race sprint.

Cheers Peter

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

Quoted message said:

I think this is what they are called, the out of round (oval) chain rings that from what I
understand allow more torque to be applied for a greater range of the revolution of the
chain wheel.

Is the use of these chain wheels common? Are they used much in racing? If not, why?

See this by the great man:

sheldonbrown.combiopace.htmlOpen ↗

[QUOTE]Originally posted by Rman
[B]

Quoted message said:

I think this is what they are called, the out of round (oval) chain rings that from what I
understand allow more torque to be applied for a greater range of the revolution of the
chain wheel. [/B]

Ben Wight said:

I think this is what they are called, the out of round (oval) chain rings that from what I
understand allow more torque to be applied for a greater range of the revolution of the
chain wheel.

Is the use of these chain wheels common? Are they used much in racing? If not, why?

Because they were a crock. You can just about make a case that it's a good idea to use an oval
chainring to increase the gear in the middle of the pedal stroke and decrease it to get the foot
over top dead center more easily, though nobody has ever been able to show that cyclist's go
measurablt faster with such a setup. However, Biopace increased the gear at the top of the stroke
and decreased it in the middle.

Racers, used to spinning, hated the way it felt, and mountainbikers didn't like the fact that it
forced a 28t inner ring when every sensible person used a 24. This is in the days when 12-28
clusters were standard, and 110/74 pitch chainsets meant 24 was as low as you could go.

And some people with dodgy knees found it made them worse.

Shimano quietly dropped it when shaped teeth and shift gates for front indexing were introduced,
claiming they couldn't get the shifting to work yet, but it would be back. Anyone holding their
breath is now long dead and very smelly.

--
John Stevenson Cyclingnews.com

Peter Signorini said:

Shimano eventually came up with their revolutionary Biopace #2 chainrings... they were *round*.

Biopace II was still elliptical, just not very so. You could still tell the difference from round
rings if you concentrated, but all it really did was convince sceptics there was no point in the
first place.

--
John Stevenson Cyclingnews.com

I went through two sets of Shimano BioPace chainrings, before they became unavailable. I loved them
and they suited me fine. Perhaps, as Sheldon Brown says, because I'm also a runner and frequently
run shortly after riding. I found that the small ring needed to be set in a different position to
the crank than the large ring-----probably because the cranking action tends to be different with
faster turnover in the lower range. My last BioPace set was lost in a fire and I've had more pains
since then, age having nothing to do with it. I do think the concept of elliptical cranks needs to
be further explored and hopefully an improved version might result. Certainly more knowledge about
the offsetting of the small from the large ring would be good.

Steve McDonald

Check out this site for details on properly ergo designed and engineered oval (eliptical) chainrings

argonet.co.ukovals.htmOpen ↗

This site also says "In the 1980's, Shimano flooded the market with their 'Biopace'
pseudo-oval chainrings and made many false claims about their effectiveness. Unfortunately they
orientated them back-to-front, giving cyclists a higher gear to push through the dead-spots!"

Cheers

Col

Ben Wight said:

I think this is what they are called, the out of round (oval) chain rings that from what I
understand allow more torque to be applied for a greater range of the revolution of the
chain wheel.

Is the use of these chain wheels common? Are they used much in racing? If not, why?

Ben Wight