tjfastback66

Greetings All -
Thinking of changing out the Shimano Biopace crankset on our Schwinn High Sierra.
Reading some news that this was a failed product - and wanting to put on something that would be period correct circa 1987.

Thoughts?

daverup 

I've got one like that on a Diamondback. It seems fine to me, hardly noticeable.

John Nolan 

Biopace might suit you—give it a try. See Sheldon.

gna

Failed in the marketplace, but I kind of like the Biopace/Ovaltech chainrings. https://www.sheldonbrown.com/biopace.html
You could just change the chainrings rather than the whole crankset. Check your chain, though--it looks really tight and may not fit with round chainrings.

madpogue 

I have that same year/model/color, one size smaller, with Biopace, and +1 above, I hardly notice the difference, if at all. I have a few other biopace-equipped bikes (MTBs, hybrids and roadies), at least one Ovaltech, and most recently a Suntour Cycloid from 1987. I can't say I could tell which is which, esp. given all the other differences between the bikes. About the only thing I haven't tried is one of these (I reckon you'd notice a difference with that....).

tjfastback66

Thanks for the feedback all - I appreciate that very much.
This is the bike for my bride to ride so I think that I will just clean her up and let it be!
All that I did so far is put some Ergon GP1 grips on because she broke her wrist last winter.

leftthread

You might want to shift it off of the large/large combination.

I would just keep the original Biopace. The chainrings don't look that worn.
But check the chain wear with the proper tool and if the chain is worn, replace the chain with a new one.

https://www.connexchain.com/en/bike-...ail/connex-808

One instant improvement would be to install new cartridge bearings in those hubs.

dddd

Since the pictured rings aren't one of the later and rounder (HP, II, SG) variants, only the big ring here is of the "rounder" (3-1/2% shape/radius variation), while the smaller rings are both the "wilder" 8% variation.

So the big ring will offer the smoothest pedaling at higher cadences without the rider perhaps bouncing in the saddle.

A shorter bottom bracket/spindle would allow use of the big ring in more of the freewheel's cogs, the limiting factors on it's reduced length being the chainring's clearance and shifting performance down to the smallest chainring.

tmnguuyen 

It was just ahead of its time. The oval chainings are getting some traction now with the absolute black chain rings. They work just fine it is inperceivable in my opinion if you don't do any heavy climbing.

trucklet

If it feels good, keep it. @dddd is right about the bigger rings. I really liked the 52t Biopace ring I had on my singlespeed, but I also had a shorter Biopace triple on another bike that felt way too eccentric on anything but steep climbs, so I swapped it.

C9H13N 

I have an ‘87 High Sierra (mine is yellow though) and one of the first things I did to it was get rid of the Biopace crank and replace it with a Deore FC-MT60, which matches rest of the drivetrain.

I hate Biopace. I’ve had it on at least 4 frames that I can remember. I know lots of people say “it isn’t noticeable” but I absolutely do notice and to me it feels like the oval shape of the rings is oriented wrong.