He could look at one of these
http://www.cyclesmaximus.com/electricassist.htm#lynch .
They're made locally and i've seen one go off a a rate of knots on the
flat. One of the guys who builds them said the motor is rated upto about
70V IIRC which would be scary. The 12V system goes pretty well.

Ignoramus32687 wrote:

On Mon, 22 Aug 2005 12:57:30 GMT, Pete wrote:

Give some thought to this , a VFT takes 240V AC and converts to DC the
rectifier side of the VFD,The VFD inverter section sees the DC and inverts
it to 240 volt AC three phase. Using a VFD and supplying 240 DC from a
battery bank of sufficient size directly into the DC side of the VFD you
will create variable frequency AC hence variable speed.His project is very
doable although I doubt if anything smaller than a car will be a big enough
platform to carry sufficient battery storage.


Yes, weight and size is my main issue with that project. I asked him
to keep me posted, dunno if he actually will go ahead with his project
or keep me posted if he does.

If I was doing an electric motorcycle, I would use a DC motor and
several small, garden tractor type batteries. I would select how many
batteries are in the circuit to control voltage and speed.

I see not much reason to use inversion, AC, phase conversion etc.

i