I ran across this on the interwebs while looking into the Q-rings. This is, as far as I can tell, the only scientific study on the subject of non-round chainrings.
I searched the forum for "Biopace", but it returned a bunch of threads that only refereed to it in passing, and I could not find one that was just for elliptical chainrings. If there is one, let me know, and I will move the link there.
What are your experiences with biopace and other elliptical chainrings? Do you love them? Hate them? Want to try them? Any shifting problems?