re Biopace, here is a quote I just wrote in response to other talk of it in the Roadie section:

[QUOTE=achoo;12419402
If there were any magical mechanical bullet already being made that would make anyone go faster on a bike, it'd get widespread use - FAST.
[/QUOTE]

Thankyou! That sums it up.

I used them, hated them. Even for a skinny, not strong, non racer like me (20 years ago and today) I and my knees didnt like them. Yes, at slow cadences "maybe" they were ok, but as someone who sometimes spins up fast on downhills or whatever, not wanting to shift up sometimes, the herky-jerky going on was just fricken terrible for knees. It just felt weird and unnatural, and frankly felt bad for the knees.

for the supposed gain in reducing "dead spot" in a pedal stroke, it was not for me worth the risk for my knees, and having to keep an eye on my cadence and not being able to (safely and comfortably) spin up on a downhill.

as I have said in other threads on this, I changed them out and unlike my usual practice of keeping **** "in case" its needed down the road, I threw these suckers in the trash.

**I totally agree with the person whose comment I quoted, that if oval rings were really a great thing that made pedalling more efficient, they would be out there still and racers would use them all the time for the X % of efficiency gain, its really that simple. I can see how for slower cadences they can maybe work, but in everyday life, I have times where I speed through an intersection, or bomb down a hill and the cadences can get high (I dont have a cadence speedo so cant give numbers) and the uneveness with oval rings is very much apparent at high cadences.
Again, if they were such a great, universal idea, they would be on bikes, I cant back it up with scientific proof, but my personal experiences and the fact that it isnt around (for me) pretty much sums it up.
Darwinian thing ( I mean, we still have bar end shifters, non-clip in pedals etc) but no Biopace.