Originally Posted by
T-Mar
This sounds like a case of the original fact being progressively exagerated each time it is retold. The original 38T and 48T chainrings were designed for 55-100rpm, while the 28T granny was intended for a maximum 80 rpm.
We always advised if you were a 60 to 70 rpm kind of guy, Biopace was good, even more so if you did not use toe clips and straps.
When I bought my first mtb, I had the shop toss the big biopace ring, kept the two smaller ones, worked well and still does.