So I watched the time trial of the Tour de Romandie. I was following it from Day 1. I also noticed that Bradley Wiggins was using an elliptical chainrings. I remember 20 years+ ago, Shimano came out these elliptical chainrings for their mountain bike cranks. It was very popular early on but they eventually dropped it and went back to the circular CRs. What's your take on the elliptical CRs, science or BS?
Last edited by ARPRINCE; 05-01-12 at 08:49 AM.
they make sense, pros use them so some of them must like em. It wouldn't benefit me, I'm slow regardless of what I put on my bike.
No spoilers please. You can edit out the part about winning.
Edit: Thanks
Last edited by Homebrew01; 05-01-12 at 08:50 AM.
Bikes: Old steel race bikes, old Cannondale race bikes, less old Cannondale race bike, crappy old mtn bike
Who said anything about winning?Originally Posted by Homebrew01
Anyway, I was doing some research and found the crankset. They called the CRs BIOPACE. Brings back memorires.)
Biopace was elliptical the other way. This is completely different.Who said anything about winning?
Anyway, I was doing some research and found the crankset. They called the CRs BIOPACE. Brings back memorires.
I may be fat but I'm slow enough to make up for it.
Some love them, some hate them, YMMV.
I like to put them on single speed bikes and watch the head scratchers who walk by my parked bike.
(click for album of my bikes)
Just call me "Dan".
I need some of those rings. They'll go well with my pet rock.
Would it matter?
Yes, there is science to the elliptical chain ring thing. It changes the effective gearing throughout the stroke. I think, as others have said, the Biopace rings didn't phase them right (i.e., didn't put the high mechanical advantage in the right part of the rotation).
I stop for people / whose right of way I honor / but not for no one.
Originally Posted by bragi
"However, it's never a good idea to overgeneralize."
my 1989ish Trek 830 MTB still has oval chainrings on suntour cranks.
they are nowhere remotely as ovalized as what Bradley Wiggins rides. in fact some people who have borrowed the bike didn't even notice.
Cross- 2010 Cannondale Quick CX Ultra (dropbar conversion)
Road- 2011 Litespeed M1
MTB- 2004 Santa Cruz Blur
It was counter intuitive to me to learn that I could run biopace on a ss/fg bike without chain tension issues.
(click for album of my bikes)
Just call me "Dan".
Biopace was not ovalized, it was a really weird, non-symetrical shape. They were not very out-of-round though. I had them on several old bikes and couldn't feel a difference. The Rotor rings Wiggins is using are profoundly ovalized, to the point that I would think front shifting is impacted. I'm surprised he uses them. I don't buy the concept, but who knows.
Even on Wiggin's bike, you can see that the RD cage isn't moving as the ovals move, the "effective circumference" is constant. Really counter-intuitive.
here's a bike from '93 with elliptical chainrings:
1893
i don't think that there is a very significant gain to be had from elliptical rings. many people have seen big jumps in their srm power numbers when they switch to elliptical rings, but this is due to the way that crank based power meters measure power. measurements taken at the wheel show pretty minimal gains. the osymetrics that wiggins and a lot of sky riders use cannot fit 130bcd cranks and maintain 53/39 sizing. they are 54/42 if i recall correctly, which could really hurt and offset any gains if you are overgeared in a climb. also, osymetrics are notoriously flexy and require you to really dial in your shifting (see wiggins chain drop on sunday). and kind of a bummer to buy something for $300 that will need to be replaced in a year or two. that said, i am still thinking about getting a pair for my compact and running 52/38 this year.
Tour de Romandie RACE SPOILER ALERT!
Not to give away what happened during the final stage TT race but he did have a MAJOR mechanical issue almost costing him a lot of time. Even the commentators mentioned the problem could have been caused from the elliptical chainrings.
Biopace wasn't really elliptical. Non-round, yes. I like them better advanced a bolt hole. Some of the Biopace MTB rings looked crazy, like rounded off parallelograms.
I think they were original Biopace 26-28 tooth rings that were nuts and they mellowed them out a bit for Biopace II. I had a couple of MTBs I swapped out the little rings on.
I kinda like Biopace otherwise. Haven't tried any of the new crop of non-round rings, like Q-rings, etc.
1980ish Free Spirit Sunbird fixed * 1996 Mongoose IBOC Zero-G * 1997 KHS Comp * 1999 Diamondback Interval * Olde Western Auto Cruiser.
http://veloviewer.com/SigImage.php?a...=distanceTotal
I have Q rings on my bike. I like em....
since when can you spoil a race that ended 2 days ago lol
The theory seems sound. And you can bet that Sky have checked out whether Wiggins is faster with them rather than without them.
"I'm not crazy; I've just been in a very bad mood for forty years."
wiggins uses them because he has knee issues,same reason he has extended axle speedplays his knees.
I thought the biopace rings were egg-shaped or something. The Rotor q-rings don't seem nearly as oval as the osymmetric rings. All I know is that seeing Wiggins' chain flopping around, I was thinking to myself that there can't be any way that's any better or more efficient. It triggered the common sense alarm.
He did have a "chaingate" moment on the final time trial.
I used biopace back in the day and at least for racing they dont work, if a racer cant climb or control his pace in the mountains it helped a lot. For regular human beings and maybe triatletes biopace works because the pace making is not even close to serious cycling racing. As for the new ones that came up lately like rotors and others, those are way more oval than biopace, but no idea if they could work. Wiggo seems to like them, sure he controls his pacemaking going uphill with them, the guy climbs but he is/was a tracker also so doubt he could climb as good as with the oval stuff using round chainrings. IMO the secret of his climbing abilities are those oval chainrings.
would love to try a set of rotors one day just to know if they work out better than biopace.
I use them and I am actively promoting them as a good product. Biopace never worked because they were designed incorrectly. Humans generate the greatest amount of power at the four to five o'clock position on a crank. Qring are the only ones out there right now doing something worthwhile. In my opinion, Rotor got it right. The long and short of it is that elliptical rings do work.
2006 Norco CRR Ultegra
2007 Jamis Quest
2007 Jamis "Riding Couch" Commuter
2010 Cervelo P3
2012 Cervelo R5 VWD
I'm riding those same rings, the osymetric rings. Felt weird at first but that feeling didn't last as long as the soreness they induced. They place the demand of the pedal stroke on your quads, and it took about a week before that deep soreness faded.
I've been on them since january, and I don't see myself going back to round rings. Once you're used to them they feel much more natural than round rings. Shifting isn't as good, and until they give the rings ramps and pins front shifting will be off par. That said, it really isn't an issue.
If I did it all again, I would be running them on a compact crank. I'm committed to my 130 BCD powermeter, and the small osymetric is a "42". On a 110 you can get a smaller inner chain ring, and the same 52 ring I run on the 130bcd. That 42 is a big gear on steep climbs.
I didn't get much info when I searched them, so I figured I would give my .o2.
http://sheldonbrown.com/biopace.html
"Biopace chainwheels are particularly suitable for touring cyclists and time trialists, or any application that involves a steady, fairly constant cadence. They allow healthy, efficient pedaling at slower cadences than is possible with round chainwheels. They are especially suitable for triathletes and mountain bikers. The triathlete benefits because the motion is a little bit closer to that of running, making the transition easier.
The mountain biker particularly benefits, because the Biopace design somewhat smooths out the delivery of power to the rear wheel. In climbing on loose surfaces, the limiting factor is often traction. The rear wheel tends to break loose during the maximum power phase of the pedal stroke, wasting most of the cyclist's energy. The Biopace chainwheel works like a storage device, storing power during the main power phase of the stroke as the feet accelerate, then delivering the stored power to the rear wheel during the "dead center" phase when the cranks are near vertical. The same average amount of power is delivered to the rear wheel, but in a smoother, less pulsating flow. All the energy is used to propel the bike forward, without the high-power peaks spinning the rear tire or causing the bike to "wheelie."
As someone who has neuropathic issues in one leg that causes a power imbalance and biomechanicl issues that make pedalling with my left leg less than fluid I find that the Biopace I have equipped on a number of my bikes benefits me greatly and delivers as promised.
I still ride round rings but can really feel the difference when I run the Biopace as they have restored what used to be what was an extremely smooth and fluid pedalling stroke and lets me push a slightly higher gear.
When people come into my shop and get to talking about having knee issues I often suggest they fit their bikes with Biopace rings as they do reduce stresses to the knees.
Posting Permissions
Reply With Quote
