BMX Hawaii Forum

i found this in one of the bmxmuseum threads.. oviously a design flop but interesting none the less.. maybe some of the "olds cool" guys can fill us in on what exactly was the concept

Used to see the eliptical sprockets on some road and mountain bikes. I think Shimano had a line called biopace if my memory is correct. The theory was that the larger side of the sprocket was set up where you had the most leverage - or inline with the cranks. And the smaller side was where the "dead spots" of a crank revolution were. But, you need a derailleur to take up the slack in the chain. On a bmx without a derailleur you would get really bad loose and tight spots on the chain. BUT...........I heard some bmxers ran them anyways.

BIOPACE!!! White rhino used to race that for a little bit BITD at Hickam. Kinda freaky feeling, but he was still burnin it up! Feels like if you were to pedal REALLY out-of-rhythm.

(09-13-2010 05:28 AM)CHEE HOO Wrote: [ -> ]BIOPACE!!! White rhino used to race that for a little bit BITD at Hickam. Kinda freaky feeling, but he was still burnin it up! Feels like if you were to pedal REALLY out-of-rhythm.

Maybe it worked better for him? I always tell him his power is only in one leg. The leg that has the "Ingano" DNA in it. His other leg is just a "mortal" leg like the rest of us.

Just kidding with you Ro.

jk

From what I understand about these, it was supposed to help spin, as stated earlier the big spots where the "power" spots and smaller were the "weak" spots, thus allowing a easier spinning gear.

It wasn't actually to help your spin, it did the exact opposite. It amplified your effort on your downstroke and attenuated it on your upstroke. Problem is, it is a poor idea on anything other than the small sprocket used for climbing. And here, I still think it's still feasible. A round chainring will allow you to get a good spin, thus creating a smoother power band as opposed to a surging one. I think I read somewhere that it was actually detrimental to the knees because it intensified the alternating pressure.

Also I think it was designed for running at a slower RPM and for long periods of time. Kinda the opposite of BMX. Then Again Mike King won the ABA grands in 17X and getting the natinal number 1 that season on one. Maybe I should give it a try, I need all the help I can get.

Changstar