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shimano biopace(7 posts)

shimano biopacedbs0
Jul 18, 2003 12:48 AM
hi guys. a friend of mine is selling me his old, barely used bike (chromo-frame, mix of 16-spd shimano 105, 100 & 600 parts) fairly cheap- less then P200. it has biopace cranks though. should i just junk it or risk my knees, or are they really that bad? there must have been a reason that they were discontinued.thanks in advance.
No risk.Ridearound
Jul 18, 2003 1:36 AM
I had these on a MTB for years with no ill effects - I'd say go for it. If you really don't like it, you can always change them out from e-bay or whatever. Personally, I never noticed the difference between them and ordinarys.

Why did they stop? Probably like most things in bikes these days - consumer saturation.

I remember when I got mine, my Dad (who used to race in his teens and 20's - so the 1950's) remarked that they had been around on road bikes in his day, and had been a French design then, and were much desired.
It is good for slow print.c722061
Jul 18, 2003 5:23 AM
I have it on my commuter bike. As long as I keep the cadence on the small ring to less than 90rpm it's fine, if it goes above, it feels weird. If you want to read more about it, go to www.sheldonbrown.com
Are you a spinner or a grinder?Spoke Wrench
Jul 18, 2003 5:15 AM
If you prefer to pedal at relatively low RPM's say in the 60's you'll love the biopace chainrings. They give you a little more leverage at the dead tops and bottoms of the stroke.

If you're a spinner and like to pedal in the 90's or so, you'll probably hate them because they make it harder to maintain a smooth pedal stroke.

If you do hate them, the solution is just a chainring swap away. With older non-sti equipment you don't need to buy the expensive ramped chainrings either. Just get the cheap plain ones and it'll shift just as good or better than with the biopace rings.
Are you a spinner or a grinder?russw19
Jul 18, 2003 7:44 PM
Spoke Wrench is right on about this! When Shimano designers came up with the BioPace concept, they had a computer design the optimum shaped chainring for a model of 500 riders biomechanics... they actually put a lot of time and engineering into this concept.... the problem was that sort of like the engineering marvel/failure of the Tacoma Narrows Bridge.. they forgot a factor which derailed the entire project. When they hooked up all these different riders to machines and electrodes to see how the body moved on a bicycle, they did one thing very wrong... they had the riders pedal at a slow cadence so the machine taking photos of their positions could keep up. BioPace is optimized for a rider pedalling at 60 rpms. As you pedal faster your body reacts differently and you spin circles instead of pushing and pulling on the cranks... it was that efficiency of the body that led riders who spin higher cadences to hate BioPace. And if the pros don't ride it, you can bet John Q Public won't either.

That's the story of BioPace and why it failed. But the good thing is that it is standard Shimano bolt pattern, so you can easily replace the chainrings with round rings.

Russ
My wife won't give 'em up. But it's an easy, cheap swapcory
Jul 18, 2003 8:25 AM
My wife's had the same mountain bike since Biopace days, and when I tried to swap for round rings, she made me put the ovals back on. She's only a casual rider without much of a spin, and she likes the feel of the Bios.
FWIW, if you do decide to swap, there are billions of round rings out there with the same bolt pattern. You don't have to change out the whole crank or anything--the bolt circle is round.
re: shimano biopace- THANKSdbs0
Jul 19, 2003 3:02 AM
thanks for the advice. looks like i'll be getting the bike after all. i'll be getting the bike. i try tio spin but i'm not at the 90rpm levels yet so the biopace rings should be ok. thanks again.