What do you think of biopace/non-circular chainrings /n/? I have

>>909754
Based Sheldon was a fan of them: http://www.sheldonbrown.com/biopace.html

I had some Biopace rings on one of my bikes for a few years; never really noticed a difference compared to my other bikes.

I've had a Biopace Crankset on my first Steelbike, and the only thing i notice about it is that its pretty much Solid and Bulletproof, though i can't really notice any difference compared to my current Shimano 105 Crankset

I feel a bit of difference when climbing. It's a little like trying to lift during upstroke. I haven't done an A/B test between my Biopace bike and one of my other bikes, although even if I did it wouldn't be terribly accurate due to tire size and geometry differences.

Haven't ridden Rotor rings or other non-circular types, but I have experience with Biopace. My experience, as someone used to spinning high cadences, is that the larger Biopace rings don't feel much different then round ones, but smaller sizes (<=32) give a very choppy feel if you try to spin. I don't have Biopace on any of my current bikes - Biopace rings do produce a smooth, consistent transmission of power to the rear wheel, but it's not really noticeable unless you're riding up a slope with reduced traction (loose gravel, ice).

File: chainrings_compared_01a.png (41KB, 800x695px) Image search: [Google]

41KB, 800x695px

>>909754
BioPace rings were really pretty mild; almost any other non-round chainring made had greater variation than BioPace did.
Pic related: a diagram I did in the past by tracing pictures of several different brands.
Do note: these are tracings of the largest chainrings. With many of the different brands, the smaller rings had a more severe shape. The small rings on BioPace triples had a distinctly rounded-diamond shape.

I have Rotor Q-rings on my two bikes. Just the rings, not the cranks.
The reason I tried them is because I had a problem with knee pain at the top of pedal strokes on longer rides (longer than ~75 miles), that nothing else seemed to help.

With the Q-rings you can adjust the phase that the long axis is on, so I adjusted the rings to push more of the effort further into the pedal stroke.
This is about 70° away from where it should have been for MAXIMUM POWER, but I didn't care about that. I don't race or track my cadence, ever.
It did help reduce my knee issues. And I liked the Q-rings on my long-distance bike so much that I put them on my commuting bike also.