Q: I have an ’87 Peugeot with old Shimano BioPace chainrings. Low gear is 42×24-tooth. My buddies with triples are killing me on climbs! Should I ditch the BioPace and install 53/39-tooth rings? — Byron M.
COACH FRED: Ditching BioPace chainrings is an excellent idea. That out-of-round design was an experiment that failed. No studies that I’m aware of showed any advantage, aconclusion that has been proved empirically because they’re no longer manufactured.
Switching to 53/39-tooth chainrings will give you a lower climbing gear, but you might also look into a wider-range set of cogs. I assume that your ’87 bike has a 7-speed freewheel. They’re still available. A 12-26-tooth freewheel would give you a 39×26 low gear. That should let you spin with your buddies on most climbs.
It works for me, and there are studies, e.g. http://blog.artscyclery.com/general/shimanos-ill-fated-biopace-validated-in-university-study/
The principle of ovalised chain rings has been proved in scientifice studies, as Norman says. The anti-Biopace critics are wrong but even in the face of the science still maintain that they are right. The simple fact is that an ovalised chainring, properly fitted, provides an advantage over a circular ring. If you want the view of an expert, instead of an ill-informed critic, take the recommendation of Bradly Wiggins.
I use Biopace and they give a very useful advantage on hills. There must be other reasons for the you getting hammered on hills, such as the build of your rear wheel or type of frame you ride.
I’ve been riding a biopace chainring on my Centurion racebike for many years. i was a racer and noticed the benefit when I started riding it. No, it doesn’t unship the chain at high cadence.