You'll get this response a few times over, but have a look at Sheldon's page on bio-pace rings;
http://www.sheldonbrown.com/
It should answer any questions you may have.
Neale
> I have an early 80's touring bike equipped with Shimano Bio-Pace rings.
> I've rarely seen them used and wonder what their purpose was? I suppose it
> should be obvious but I prefer the round rings. Thanks much. Rick
> millere@telenet.net