>Has anyone ever made variable cranks?
>It occurs to me that while it wouldn't be as sturdy, one could
>probably make crank arms that had either more than one place to attach
>the pedal or, ever more difficult but more useful, a continuous range
>of positions (probably made by sliding the pedal mounting point along
>the crank). If you could do the latter, you might also be able to
>make it possible to adjust while riding, which would be an alternative
>to a geared uni.
I've seen pictures of the old penny-farthings (high wheeler bicycles) with
variable length cranks. Basically an oval slot in the end third of each crank
for the pedal axles to clamp down at any point along the slot.
A way to adjust leg extension without moving the seat. Or long cranks for
hilly terrain, shorter cranks for the flats. Not adjustable while in motion
though.
I was brainstorming with Tom Miller about this idea for the 100 meter
unlimited class events at Unicycling Society of America's National Unicycle
Meet '95. A larger wheel diameter with cranks that started out long for
acceleration off the line but got progressively shorter as you rode.
It was an interesting concept but we didn't progress to figuring out the
mechanical details ...It might actually be easier to build a wheel that
changes diameter as speed increases.
Dennis Kathrens