[email protected] (Chris Zacho "The Wheelman") wrote in message news:<
[email protected]>...
> From:
[email protected] (Andrew Bradley):
>
> Edited for space (this post is long enough already!):
Space no problem. Think you over-edited a bit, Chris.
> >Biopace is better than round?
>
> Not better. Just another way of achieving the same thing as spinning on a round ring, a smooth,
> even flow of power to the wheels.
I would like to see power readings to confirm that but don't see any advantage unless in low
traction conditions when my experience was biopace made things worse.
> >Can you explain this better?
>
> Sheldon can give you the scientific explination, he has more room on his webpage that I do here:
>
http://www.sheldonbrown.com/biopace.html
Mechanical energy is stored and released near the "dead spot" (as indeed it is with a round ring to
some extent) but there's more to it than that. I'd like to see some real world power data or a more
detailed explanation taking into account the effect of muscle work.
>>Don't the legs always have to follow pedal motion?
>Only in that they have to move in a circular path.
What you mean, they can chose a different speed or something?
> The human leg wasn't "designed" to move in a circle. It was meant to :
> 1. Support and lift the body against gravity, and:
> 2. Move it forwards.
>
> Since the first requires more force, the muscles which do this are stronger. Hence when they are
> used to turn a bicycle crank, the apply more force when they are in use. This happens when the
> up/down half of the pedaling cycle, and the pedals speed up.
It doesn't speed the pedals up to any degree unless you are on a steep hill, in which case you get a
biopace effect for free. I don't see the point you are making.
> When the pedals move through the for/aft motion, the weaker muscles are used. However, they are
> not as strong, and therefore cannot push as hard.
If they are not as powerful, they are not as powerful- nothing to be done, is it a good idea to hang
around in that sector?
> Sometimes they can barely even keep up!
True, but not normally a problem with a round ring
>The result is an interrupted "push-coast-push-coast" transmission of power to the wheels.
>
> Think of trying to drive your car by rapidly stepping on the gas, then lifting your foot off it,
> again and again and again for the entire trip. How do you think this would affect it's efficiency
> (gas mileage, if you wish)?
This seems to describe the feel of biopace to me. You'll have a hard time convincing people there's
an efficiency gain unless it's due to lower cadence (there isn't an efficiency gain with
"spinning").
> Spinning reduces this interrupted power by causing the feet to move at a more even rate around
> the entire circle, the way the pedals move with round rings. Result; an even flow of power to
> the wheels.
An even rate of foot movement, how do you mean? If the rate does get significantly uneven up a
decent hill, it tends towards biopace. That's either good or it isn't.
> Biopace works "diametrically opposite" (the other way around) by changing the speed of the pedals
> as they rotate, repeatedly speeding them up and slowing them down in time with your feet (when not
> spinning). Result; an even flow of power to the pedals.
Surely the pedals are always in time with your feet, no?
Andrew Bradley
