Re: New Idea for EV Bike

["Randy Pollock" <randy@alumni.caltech.edu>]

John Bryan <jbryan@micron.net> writes:
>  A ZAP (or similar-type) bike equipped with a specially modified drive
> roller. The roller is a custom fit to an aggressively treaded tire, 90 deg.
> features in the tread like knobs and robust ridges would be best. The roller
> would deeply engage the tire when power is applied, but would never generate
> any actual 'tension' with the tire...
>
> How best to make such a thing? I have an extra roller to use for the
> core, the finished unit would be a bit bigger than a std. roller which would
> give a slightly higher top speed. I started realizing that the drive roller's
> circumference would need to be a function of the repeat distance of the tread
> pattern. Basically, if you took a piece of clay and rolled in on the wheel
> until you got a smoothly repeating pattern with no overlaps or pinching, that
> would represent what you wanted to end up with.

What you are describing is a set of gears.  This problem was solved very
nicely in the late 1800s.  A large library (certainly at a college with
mechanical engineering courses) should have books on gear design.  There are
well defined relationships that define the optimal shape of each tooth,
number of teeth per revolution, helix angle of the teeth, etc. to minimize
rolling resistance and wear.  Some texts will deal with wear patterns if one
of your gears is much softer than the other.

The math involved in the simplest versions of these equations is at about
the high school geometry level but it quickly rises to calculus/differential
equations depending on how fancy you are trying to get.  It should be a good
start though.

Good luck.

           - Randy