Biopace and modern oval chainrings are not the same thing. Biopace had the clocking of the "oval" wrong and made the gearing lower in the strongest portion of the pedal stroke and higher in the weakest part of the stroke. This put more stress on your legs and joints at the point where they were least prepared to deal with that stress.
https://absoluteblack.cc/home/menu-1...20rings%20work.