Biopace Rings and Pedal Stroke

[Uncle Jam's Army]

A lot of the recent pedal stroke discussions have made me think about "Biopace" rings. Biopace was a huge flop in the 80's, but elliptical/oval rings seem to be more common now, with some wild shapes (Osymetric rings). I know the idea behind them (getting over the dead spot quicker) and even used Rotor Q-rings on a SRAM crank I had for a few months two years ago. After a ride or two, I really didn't notice any difference in them.

What say you? A useful tool for a more efficient pedal stroke or bunk?

[skouri1]

they shift worse. that's about the only thing you can say about them for sure. :)

[josephr]

Sheldon Brown was a fan....I have them on one bike currently but its my 'retro' bike so its more because its period correct. On the mtn bike I had before my current, I replaced the small ring with a biopace and it seemed to help spinning/climbing. But everything I ride now is round. I thought about the Oysemetrics, but a little out of my budget.

http://sheldonbrown.com/biopace.html

[joco]

Its interesting when you look at all the oval rings... Osymmetric rings are 90 degrees offset from other rings.

[berserk87]

I rode Biopace rings on an old Bianchi that I had when I was a noob and could not tell any difference between these and regular round rings. Then again, I was a noob - the bike was a 63cm and I ride a 56 - so that's where I was back then.

I have a pal that has tried and finally abandoned the Rotor Q thing. The front shifting was especially crappy and he never could get it to play nice. Other than that I can't recall that he thought it made any difference in terms of performance.

[Ken Robb]

My 1989 MB-3 Bridgestone came with Bio-Pace rings in a 3x7 and I thought they were fine but replaced them with round rings due to unavailability of BP rings.

[Northmeadow]

I'm pretty sure I saw Chris Froome riding some type of not-round ring in Ruta Del Sol

[kramnnim]

Its interesting when you look at all the oval rings... Osymmetric rings are 90 degrees offset from other rings.

They are 90 degrees off from Biopace, but are the same as Rotor Q Rings...

Froome has been using them for a while...

[ultraman6970]

In racing world biopace chainrings did not work, you can't spin with them, you cant do sudden changes in the pace with them either, you cant keep high cadence with them... they just suck IME.

For a regular joe that is not racing probably they will work, but at least to me and like all the guys that raced when I was racing, nobody used them but maybe xtreme climbs, besides that are just useless...

As for the new oval chainrings no clue, havent used one and for what the cost probably I wont use one ever.

[Hank Scorpio]

I read something fairly recently where a "supposed" independent lab tested the Q-rings against traditional round rings and they found that once a rider acclimated to the rings there were gains to be had from recreational cyclist through more competitive levels. The test was sponsored by Rotor and it may have been in Bicycling magazine which has about as much cycling credibility as MAD magazine. I will see if I can locate the article.

Oh here is the white paper found on Rotors own site

http://www.rotorbikeusa.com/images/science/pdf/sscivol06no01paper04.pdf

[cnighbor1]

A lot of the recent pedal stroke discussions have made me think about "Biopace" rings. Biopace was a huge flop in the 80's, but elliptical/oval rings seem to be more common now, with some wild shapes (Osymetric rings). I know the idea behind them (getting over the dead spot quicker) and even used Rotor Q-rings on a SRAM crank I had for a few months two years ago. After a ride or two, I really didn't notice any difference in them.

What say you? A useful tool for a more efficient pedal stroke or bunk?
I like Biopace ring on the big ring only has you can turn one bigger gear than normal Using latest design which was less Oval. One needs to be a smooth pedal style and not just mash down after going over the top is my experience
I have some FS

[cnighbor1]

In racing world biopace chainrings did not work, you can't spin with them, you cant do sudden changes in the pace with them either, you cant keep high cadence with them... they just suck IME.

For a regular joe that is not racing probably they will work, but at least to me and like all the guys that raced when I was racing, nobody used them but maybe xtreme climbs, besides that are just useless...

As for the new oval chainrings no clue, havent used one and for what the cost probably I wont use one ever.
Except the winner of the tour de France won on radical oval big chainring
Peter Wiggins

[JAllen]

I had them on an older KHS mtn bike. I didn't have the bike for very long, but I definitely liked them. I'd be very interested in outfitting something with them. I'd also like to try them on a SS.

[cnighbor1]

Except the winner of the tour de France won on radical oval big chainring
Peter Wiggins

wrong dude it is Chris Froome

[kramnnim]

I think Wiggins used them when he won, and Froome did as well. But Wiggins went back to round.

[Grant McLean]

I think Wiggins used them when he won, and Froome did as well. But Wiggins went back to round.

Yes, Wiggins used them on his bike during the 2012 season he won the Tour,
and the gold in the Olympic TT.

http://www.muddymoles.org.uk/images/olympics-wiggins-tt.jpg

[wtex]

I've been tuning up the bikes for spring which includes swapping between a 2010 Centaur group, 7900 group, and a Sante Biopace group on a Schwinn Circuit. Anyway, until this thread came up, I had forgotten the Circuit had Biopace, so whatever ovalization is at play I have not noticed at all when riding.

[Tony]

they shift worse. that's about the only thing you can say about them for sure. :)

The shifting for me has been outstanding! It happens so quickly and quietly sometime I"ll look down to see if it really shifted . I'm using Rotor Aero Q rings on a DA 7700 crank, FD and a 10 speed Sram chain. Both rings are set in the 3 position.

[ultraman6970]

Yes he did, but remember one thing... biopace and the new generation of oval chainrings are maybe 20 to 25 years appart. Biopace sucked in the road IME and other guys that were racing with me, nobody liked them but maybe the guys that were having serious issues climbing and controling cadence while climbing that were the least.

As i said before no idea about the new oval chainrings, look like thy work, at least they worked for wiggo... but hard to tell, too expensive investment just to test them. Again.. biopace sucked for me, no idea about the new ones, the shape is different to biopace also :P

Except the winner of the tour de France won on radical oval big chainring
Peter Wiggins

[jlwdm]

Is Perer Wiggins related to Bradley Wiggins?

Jeff

[Ti Designs]

Biopace was a huge flop in the 80's, but...

Did even worse at the track...



Non-round chainrings are simply an attempt to better adapt a machine (the bike) to the characteristics of it's motor (the rider). Before we look at a complex system, let's look at a simple one - a four cylinder engine (I've built and tested a few race engines, I know they're anything but simple, but for this case...) All four cylinders are the same, they are all offset by 90 degrees, add a little flywheel and you have one steady torque output. Now look at the human body, the four main muscle groups that power the pedal stroke are very different in their ability to generate torque or velocity. Imagine an engine with one long stroke cylinder next to one large bore, short stroke cylinder. The long stroke cylinder generates a lot of torque but is very limited in how fast it can reciprocate. The short stroke cylinder doesn't reach it's power band until it's past the limits of the long stroke cylinder - that's pretty much what you have with the two largest muscle groups. From an engineering standpoint, the two muscle groups are 90 degrees out of phase, and there are two sides, so the gear ratio of one muscle group is the X-axis of the chainring, the gear ratio of the other is the Y-axis.

Add the human body into any engineering project and things start going wrong. As a machine, the human body has the worst quality control ever - some are 6'4", others 5'1", and the ECU doesn't work very well (most people don't learn how to pedal very well). Biopace was an attempt to increase the gear in the downward phase of the pedal stroke. The problem is most people borrow the skill set from walking, they push down with their quads (which generate speed far better than torque). So they're going up hills, tension on their quads goes past the muscle's tensile strength and they feel sore the next day...

In studying the pedal stroke, I've built a machine that can test for instantaneous torque - how much torque there is at any point in the pedal stroke. Given a map of where the actual torque is applied to the pedal, a chainring shape can be designed to work with that. That chainring shape doesn't travel well, my characteristic torque curve probably isn't the same as yours...

So now I have to look at the duty cycle of the large muscle groups and the effect of changing speed of the pedals with each rotation. For acceleration, or the widest range of cadence, changing the speed of the pedals doesn't work well, but for steady state power it could. Let's say I wanted to put all of the load on the largest muscle group (going back to that video on flat pedals vs. clipless), I could slow the pedals on the down stroke to increase the duty cycle of my glutes. The problem with muscles is that they don't get blood flow under tension, so you have to pay attention to the ratio of time under tension to the total time of the pedal stroke - the duty cycle.

All of my testing had been on one person (me) using a round chainring to get a torque map (which changes a lot from one day to the next). I must admit that matching that curve to a chainring is tempting...

[dnc]

Did even worse at the track...

Biopace was an attempt to increase the gear in the downward phase of the pedal stroke.



Using Biopace cranksets

Dear Lennard,
Bradley Wiggins used Biopace chainrings in the crucial time trial in the Amgen Tour of California. He quoted an advantage of some 40 seconds over the course. With the amount of data collected and analyzed nowadays, this is no longer subjective.

I was given a Biopace crankset a long time ago and tried it for a while. With multiple bikes, the differences switching is just too small and takes away from the enjoyment.
I am a firm believer that there is nothing new under the sun. Do you know what the wisdom is for people that have tried this?
— Curious Bill

Dear Bill,
There is an extremely critical distinction between Shimano Biopace chainrings and the Osymetric chainrings used by Wiggins in his 2012 Tour de France and Olympic victories and by Chris Froome in the same Tour, as well as the Rotor chainrings used by other top riders. However, I was under the impression that Wiggins used round chainrings in the Folsom TT in the 2014 Amgen Tour; here it is in action.

Biopace, like the Houdaille Powercam crank concurrent with it back in the early 1980s, gave the rider a smaller gear during the power phase of the pedal stroke and a higher gear over the top and bottom of the stroke. In other words, the time spent in the power phase was reduced, and the time spent at the “dead spots” was increased. This never was shown definitively to offer an advantage.

[Ti Designs]

Biopace was an attempt to increase the gear in the downward phase of the pedal stroke.

Biopace gave the rider a smaller gear during the power phase of the pedal stroke and a higher gear over the top and bottom of the stroke.

Well, one of us is wrong. Since increasing the gear in the power stroke makes sense, and decreasing the gear is really stupid, I'm gonna guess that I'm wrong.

[milkbaby]

^Yes, Biopace is 90 degrees offset from the current wave of non-symmetric rings like Rotor and Osymetric. Not sure why it was tho...