Biopace and fixed is less than ideal.

There is a very definite "lash" at certain points in the crank's rotation that can be felt, similar to a loose crank arm or uncentered and out of round chainring. Which is essentially what Biopace is to the fixed rider.

*lash is when the chain is loose and the cranks can move up/down a few centimeters even though the wheels are stationary. This translates to an odd sensation when riding. If you've ever used a fixed 2/3 speed hub you may be familiar with said sensation.

Sell the rings on eBay and buy a proper fixed ring.