The marketers of Biopace made a crucial error of judgement: too much information. In particular, they mentioned that the Biopace design was optimized for cadences
of about 90 rpm and slower. Many readers interpreted this as an indication that Biopace chainrings would somehow interfere with pedaling faster than that. This perception caused a bit of a self-fullfiling prophecy, and the Conventional Wisdom arose that Biopace was bad for high-performance cyclists for this reason. I used to believe this myself, but I rode them anyway because I appreciated their other virtues.