Originally Posted by MKRG
Biopace are not round and they are "directional", so...yes.
I got the not round part, how are they "directional"? As in how does mounting it one way or another on a fixed gear one chainring bike matter?
Honest question, Sheldon only says this about mounting:
For installing Biopace chainrings, the orientation should generally be preserved. Each Biopace chainring has an "indexing mark." This is a small tab pointing inward toward the middle of the chainring.
For the record, i've tried biopace on fixed gear and the variation in chain tension is just a bit too disconcerting in regular use.