Mark Bulgier wrote:
>I don't get too worked up about BioPace but it bears mentioning that they
>worked nearly backwards to the Bullseye and other previous non-round rings
>dating back to the 19th century.
>
>Those older designs worked as Jim said, increasing your gear during the peak
>power zone. Biopace decreased the gear in the power zone, which made the
>rotation accelerate; the idea was the higher gear in the "dead spot" would
>capture the momentum of the leg at the bottom of the stroke, momentum
>otherwise lost with normal rings (sez Shimano).
>
>Note, I don't believe that good cyclists lose energy this way, but it could
>be that inexperienced cyclists are more efficient with Biopace.
I don't think there's any fundamental difference in efficiency, but Biopace is easier on the knees, because the transition from pedal-going-down to pedal-going-up is slower, so there's less of a snap as your feet go over the top/under the bottom.
This was the principal drawback of the older ellipticals that were oriented 90 degrees off from Biopace. These were notorious for causing knee problemw, whereas Biopace is actually easier on the knees than round.
The other advantage I've noticed with Biopace is in off-road climbing, where traction/wheelies is the limiting factor. The Biopace system acts sort of like a capacitor, smoothing out the drive peaks that break the tires free (or pop the front end up, depending on how you've got your weight distributed.)
For more on this, see: http://sheldonbrown.com/
>As to the relative timing of Biopace and Suntour OvalTech: at the shop I
>worked in, Ovaltech came in later. I always assumed it was a Biopace
>knockoff.
That is my understanding too.
Sheldon "Point-Symmetric Egg Curve" Brown
Newtonville, Massachusetts
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