[M_a_t_t]

If you talk about details like that have you considered what it takes to make the battery you are using? or the materials that your bike is built of? Or even the manpower required to manufacture those materials?

Plus the whole human efficiency argument is almost non-sensical. Most people have everything listed atleast a little in their lives and adding a little extra doesn't add as much as the initial useage. I get most of my exercise by cycling anyway, so for me using an e-bike would negate that benefit I am getting. Arguing is pointless without any numbers though. Once you get a Mi/Kwh number post it up and we can compare it.

To get back on topic:
I have been considering adding a small go kart engine to the rear axle of my car to use as a highway cruiser. I was going to get a knuckle, hopefully from the awd previous generation of my car, if not then just knuckles from the front of another fwd car so that I can use a cv axle to power the wheel. It'd be one wheel drive, but as with any open diff it should be fine. Any way I evaluate it it just isn't as cost efficient to go with electric drive. Not quite the same as what you are proposing in this thread though.