Re: New Idea for EV Bike

[Jessica & Donald Jansen & Crabtree <crabtrdw@earthlink.net>]

Hi-
This would be a gear shape design problem, both the drive wheel and the tire
tread, not impossible but difficult.

 A few years ago SEVA held an electric vehicle show in the U of W  parking lot on
Montlake Flat in Seattle.
There was an EVbike at the show (a very clean conversion) that used a knotched
timing belt type of drive.
I beleive it was a 3/8 pitch belt and about the same width. The drive sprocket
was an off the shelf alum. one.
The part that intrested me was the driven sprocket on the wheel. It was 20+
inches in diameter (I didn't
measure it, smaller than the rim). I don't know if this was a custom part or not.
It appeared to be a long
narrow strip of sheet metal with rectangular holes punched in it and rolled into
a circle and welded at the ends.
If I remember correctly there were tabs bent inward at 90 degrees to the rim and
secured to the spokes.

Steve Lough might remember the owmers name and the bike.

John Bryan wrote:

> Hello All,
>         Last night I continued brainstorming an idea that first occurred to
> me about 2 years ago. Unfortunately, I'm at a loss to determine the details
> of just exactly how to go about it. Here's the idea:
>
>         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. All power would be transferred to the
> sides of the tire's vertical features. This system has tremendous advantages,
> if anyone wonders about them I'd be glad to elaborate.
>         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. I suppose a mold could be
> made from this clay plug, but could there be a much easier way to do this
> that I've overlooked? I can also see real problems with getting the mold to
> release from the part, unless it had many sections. Also, any thoughts on
> which compounds might be best for molding the drive roller from? Most
> important of all, might I just be off my rocker with this whole idea?
>         Computer aided machining of the part from aluminum would rule, but
> alas I'm at a shortage of equipment to pull that one off.
>
> John Bryan