Are eliptical chainrings effective? Possible Duplicate:
  What is the deal with oval chainrings?  




I know that eliptical chainrings have been around for a long time and their use seems to have peaked back in the 70's &amp; 80's.  I recently saw a professional rider using them in the TDF and I started thinking...

Is there any empirical data that supports or refutes the claim that eliptical chainrings provide more power output with less muscle fatigue?
Sheldon brown offers a full breakdown of the biopace rings here

This answer here may be what you need