Non-circular chainrings

stopped_clock · 21-09-2009 7:37am #1

I stumbled across a piece about Shimano Biopace chainrings on Sheldon Brown's website and ISTR Bradley Wiggins using some sort of unusually-shaped chainset in the TdF TTs.

What's the story? Are they just a gimmick?

Lumen · 21-09-2009 7:43am

stopped_clock wrote: »

I stumbled across a piece about Shimano Biopace chainrings on Sheldon Brown's website and ISTR Bradley Wiggins using some sort of unusually-shaped chainset in the TdF TTs.

What's the story? Are they just a gimmick?

They're Rotor Q-Rings. I've been considering getting them in an attempt to maximize my gimmicks to weight ratio.

Raam · 21-09-2009 7:54am

I'll go for.... gimmick. If they were really good, all the guys would be using them.

stopped_clock · 21-09-2009 7:59am

Would you get them onto a fixie or would the chain tension vary?

trad · 21-09-2009 7:59am

Used shimano bio pace chainrings in the 80's when they came out first. You would notice a slight difference. The eliptical shape is trying to even out torque at the top and botom of the revolution when you leg changes direction.

tunney · 21-09-2009 8:02am

Lumen wrote: »

They're Rotor Q-Rings. I've been considering getting them in an attempt to maximize my gimmicks to weight ratio.

I'll fish out the study I read at the weekend, no proven improvement in power output.

Lumen · 21-09-2009 8:02am

trad wrote: »

Used shimano bio pace chainrings in the 80's when they came out first. You would notice a slight difference.

They're not the same as biopace.

Lumen · 21-09-2009 8:05am

tunney wrote: »

I'll fish out the study I read at the weekend, no proven improvement in power output.

Yeah, but they look cool, in a Drillium kind of way.

I read a few reviews a while back. The major downside is degraded shifting, although people claim to be able to get perfect shifting with proper setup.

Some people say they suffer leg cramps. Others say they can push a higher gear.

I think (like crank length choice) it's probably impossible to prove one way or the other since it takes too long for the body to adapt.

They're not cheap.

Lumen · 21-09-2009 8:11am

Raam wrote: »

I'll go for.... gimmick. If they were really good, all the guys would be using them.

Q-Rings can be considered a crutch for poor pedalling technique. Therefore it's not surprising that pros don't use them, since their pedalling technique should be near perfect.

That doesn't mean that amateurs can't benefit from them.

Raam · 21-09-2009 8:13am

Lumen wrote: »

Q-Rings can be considered a crutch for poor pedalling technique. Therefore it's not surprising that pros don't use them, since their pedalling technique should be near perfect.

That doesn't mean that amateurs can't benefit from them.

You justify your prospective purchase anyway you like.

Lumen · 21-09-2009 8:18am

Raam wrote: »

You justify your prospective purchase anyway you like.

Your teflon-like resistance to gimmicks is impressive. I will wear you down, one way or another.

stopped_clock · 21-09-2009 8:19am

The arguments about varying leverage through the stroke seem to make sense, but any articles I've read tend not to come to a conclusion.

Raam · 21-09-2009 8:59am

Lumen wrote: »

Your teflon-like resistance to gimmicks is impressive. I will wear you down, one way or another.

A power meter and deep section carbon wheels will be my next purchases. I'm just trying to find a pair which are economical and pretty enough to go with the Cervelo.

scottreynolds · 21-09-2009 9:03am

Lumen wrote: »

Therefore it's not surprising that pros don't use them, since their pedalling technique should be near perfect.

Does Carlos Sastre not use them ..............

Lumen · 21-09-2009 9:03am

Raam wrote: »

A power meter and deep section carbon wheels will be my next purchases. I'm just trying to find a pair which are economical and pretty enough to go with the Cervelo.

Gigantex 50mm from £415 a pair, though you'd have to get over your tubular aversion.

Lumen · 21-09-2009 9:05am

scottreynolds wrote: »

Does Carlos Sastre not use them ..............

Yes, there are odd cases (Wiggo mentioned above), but you never know with pros - they're reportedly a susperstious bunch, and they're not spending their own money.

scottreynolds · 21-09-2009 9:05am

Raam wrote: »

A power meter and deep section carbon wheels will be my next purchases. I'm just trying to find a pair which are economical and pretty enough to go with the Cervelo.

There's some awesome Reynolds yokes I saw onlive last week -- all new for 2010 and they are econimcal (compared to buying a new car). Surely you'll have to consult images of Mario to see what he's using.

Raam · 21-09-2009 9:17am

scottreynolds wrote: »

There's some awesome Reynolds yokes I saw onlive last week -- all new for 2010 and they are econimcal (compared to buying a new car). Surely you'll have to consult images of Mario to see what he's using.

The Reynolds are lovely but also very expensive. The wheels from the manufacturers of the same name ain't bad either. :pac:

scottreynolds · 21-09-2009 9:50am

Raam wrote: »

The Reynolds are lovely but also very expensive. The wheels from the manufacturers of the same name ain't bad either. :pac:

Thankfully only people of calss use Reynolds on both counts.

cdaly_ · 25-09-2009 8:00am

stopped_clock wrote: »

The arguments about varying leverage through the stroke seem to make sense,

I had a go of this kind of setup a few months ago when I bent a chainring in a crash. It was bent such that on the 52 the chain would come off every half turn (and then come on again on the next half turn). I dropped down to the 44 ring and spent the rest of the ride doing half-turn-44, half-turn-52. That's gotta be the same thing innit?...

doozerie · 25-09-2009 10:12am

Lumen wrote: »

They're not the same as biopace.

From what little I have read of the current biopace, I think that Biopace rings in the 80's were the same as now. I don't know whether the same idea from other manufacturers differs though.

Shimano Biopace chainrings came fitted as standard on a bike (Raleigh) that I bought new in the late 80's so at least one manufacturer had embraced them at that time. I found it hard to tell how much difference they really made as that bike had, for me, lots of other novel/modern aspects to it that made it very different from my previous bike. I seem to recall though thinking that the rings provided good acceleration but that spinning a higher gear felt weird and a little bit like pedaling squares - when the chainrings wore out I replaced them with round rings and found them better for me, or at least more consistent anyway.

billy.fish · 25-09-2009 9:31pm

Lumen wrote: »

Yes, there are odd cases (Wiggo mentioned above), but you never know with pros - they're reportedly a susperstious bunch, and they're not spending their own money.

Yeah cause they pay for their kit....

RDM_83 · 25-09-2009 9:40pm

I actually have a biopace chain ring on my bike at the minute and have to say I don't notice a difference on it (no direct on off comparisons yet), possibly it is however why shifting is so bad on it though that could be my misuse/lack of tuning skills

dave2pvd · 25-09-2009 11:38pm

Deignan has been riding on Rotor cranks this year. I don't honestly know if he uses the elliptical Rotor rings or not. The Cervelo team is sponsored by Rotor/Q-Rings.
Last year, Bobby Julich used Q-Rings all season. Despite being his last year, he did rather well. I'm sure that was 100% due to elliptical rings

Non-circular chainrings

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