armybikerider

I just caught some of today's stage of the Tour de France on Versus. They were showing close ups of Bradley Wiggins' time trial bike and it had out-of-round chain rings....similiar to the old "bio-pace" rings that Shimano popularized several years ago.

Anyone else see this? Please don't tell me that bio-pace rings are making a come back!!!

David

McTufferton

I heard the same thing. First thought was that they did away with those years ago (well before my time, btw).

grolby

They're the opposite sort of elliptical chainring from Biopace - the larger diameter is engaged on the downstroke. The whole thing is actually very annoying, since Rotor is making it out to be this massive innovation when elliptical chainrings are one of the oldest ideas in the book. They've never really caught on. Maybe it's because no one else has realized their potential and sought to bring them to market as effectively as Rotor, but I think the real answer is obvious: elliptical chainrings are stupid.

dmb2786

works for some

armybikerider

I had them on a mountain bike back in the 80's. I was glad to see them disappear.

David

currand

I read a review of them that cited a study showing they didn't hurt under "normal" conditions and may have been marginally beneficial under certain conditions (I think it was sprinting). Sadly, quick google search hasn't located the article. I thought it was on Pez. Anyone remember that one?

Homebrew01

I guy I ride with sometimes has some kind of non circular chainrings. The odd thing is, I'd expect to see his rear derailleur cage move a bit since the amount of chain being pulled is supposed to vary during a revolution, right ? But I was staring at it for a minute and couldn't see any change. Either the amount of difference of chain pull is so miniscule I couldn't see it (enough to benefit ?), or my brain is confused.

pjcampbell

I had Rotor cranks... they were fine. You could get used to them just like anything else. I wouldn't say they're worth any extra power.

grolby

It's just a very, very small change in the amount of chainwrap. I can see the RD cage moving back and forth a bit when I spin the pedals backwards on my Biopace-equipped road bike, but it's a tiny movement - small enough that there's no way you would be able to see it on a moving bicycle from another moving bicycle a few feet away. And that makes sense; we're talking about an effective change in chainring size of less than 1 tooth each way from the nominal size.

ETA: And by the way, I don't think that (for example) Biopace rings are all that bad, though I prefer round rings. And likewise, Rotor-type rings are probably fine, too. What I think is absurd are the claims of performance advantages. That's just difficult to believe.

KendallF

FWIW...

https://www.rotorbikeusa.com/pdf/Q-Ri...Volladolid.pdf

merlinextraligh

damn, so now I have to buy the Quarq with the Rotor crank?

Racer Ex 

I've never tested the power output, but in my case the lactic buildup reduction was valid. It was especially noticeable at Gila where I ran a round 56 big ring and elliptical small ring.

The engineering concept basis is sound.

KendallF

yes, just drop off all your old, useless sh*t at my house.

fly:yes/land:no

+1

they don't seem to have them listed on their site anymore, but for a while rotor was making 144bcd q-rings. they were used on the track, where there is no derailleur to ease out the tension. that leads me to conclude that there can't be too much play in the derailleur from rotor rings. the o'symmmetric rings, though, might be making a little bit bigger changes in tension.

travkat

I am currently on the rotor Q rings and have not had any problems at all with them. I don't notice any perceivable power gains with them, but I definitely notice a lack of fatigue over given distances that I used to do with my round rings at the same pace/speed/effort etc. I think if they benefit me at all it is in that department. My good friend Rebecca rides them on her mtn bike as they are her sponsor, and she has a notoriously square pedal stroke and the rings have helped smooth her out a lot by getting her through the deadspots in her stroke quicker.

my .02

calves2997

I have Rotor Cranks on three bikes,an I feel that compared to my other cranks ( Chorus 11 and Ultegra) they have significantly decreased my fatigue levels over long distances. Their problem is that for modest power outputs ( say average of 200 watts or less) their increased efficiency is counterbalanced by increased weight and much increased resistance. These cranks have 5 main bearing, one of which is a very large spider gear bearing. Even on my Ti set with ceramic bearings they have significantly more drag than my other cranks.
I think these are best under higher power outputs, such as those seen in very steep climbs, or by much more powerful athletes than me.