My first MTB had a Shimano Biopace chainset fitted.

The concept was about smoothing the mechanical advantage throughout the revolution of each turn of the cranks, to deliver more uniform power output.

It seemed to work, but I’m wondering why Biopace never really caught on.

Anyone know why?

Shimano got the alignment wrong – it worked much better if you rotated the rings one bolt-hole clockwise. Or was it anticlockwise?

Really, enough ovalisation to make a difference means the front mech won’t work nicely. Great on things with one front ring, though.

I had biopace on one of my first road bikes. Didn’t know enough back then to know if it made a difference or not (in a positive or negative way). Certainly the likes of Rotor and O’Symetric are going at the principle from exactly the opposite perspective to how shimano did back in the 80’s. I’m actually tempted to try a set of rotor Q rings on the road bike this season.

Years ago l couldn’t figure out why my knees would ache all evening after cycling home, then read that Biopace chainrings could cause knee pronlems. I took them off and never had a problem again.

Really, enough ovalisation to make a difference means the front mech won’t work nicely. Great on things with one front ring, though.

this plus lots!

Coincidentally, I’ve been riding my original Biopace-equipped Saracen this week- helped with spinning Marathon Winters on my commute. Aren’t Q rings/rotors the “new BioPace”?

Took mine off to clean them once. Never did work out which way they were supposed to go back on.

Still got the 2 rings in one of the spares boxes.

Aren’t Q rings/rotors the “new BioPace”?

they work the other way round…Hated biopace, love Q rings and other elliptical ring. I briefly went back to round ring recently on one bike…it felt bloody horrible and really noticeable on a singlespeed. With gears….don’t know if it’s such an obvious difference.

wouldn’t it be nice if I could turn all those spare bio pace rings into modern ovals? 😆