Chapter 1. The sidewinder.
At this stage I think I can say that I know about each and have ridden and built each configuration of ebike or electric bike motor system. I guess that is what building these first in my dungeon like basement in Providence, RI and then doing it in a shop here in Portland, OR for the last 11 yrs has gotten me: some insight into what works for what and doesn't and why it's just more fun with a motor!
So I was always fixated with the idea of a transmission for a motor like a motorcycle. The tranny multiplies torque and makes a slug into a sidewinder snake(you know the ones that can slither up a sand dune in a flash.) Torque is the key. If one wheel rev is powered by 100 motor revs then things are going to happen like acceleration and power. I thought I would make a bike that accelerated like a motorcycle and could go up any hill in front of it. Well, it sorted ended up that way.
I first tried to put the motor in front of the chainring and gear it down to pedal speed. This proved more difficult than I thought. I just bolted a L shaped piece of aluminum to the bottom the a GT Ruckus that has this strange flat at the bottom of the downtube. Then the motor (a Cyclone 1200w) was bolted to it using the adjustable bracket it came with.
Now this was fine but the reduction was not enough to make it worthwhile. I found a 62 tooth downhill sprocket on ebay and adapted it. Now there was torque. So much in fact that the chain would not handle it and the bracket needed lot's of reinforcement.
Mind you I was using LiFePo4 batteries that could make 50 amps and the Cyclone controller could pass 40+ amps at a charged voltage of about 60 volts. So about 2400+ watts! This thing was now a monster that could out accelerate a car(minivan or Geo metro ;-)
But that chain just would not stay on and would break. I needed a better solution. So, I thought why not mount the motor right at the rear wheel and bypass the front pedals all together. No need for 62t sprockets and frooky brackets. Only problem: how do you shift it? Nuvinci N171 had just come out and statton inc. made an adapter to mount a gas motor on a rack (yes, I did this too.) just above the tire.
The extra sprocket is the original minibike chain one that Statton used. I just welded a bike one on it. And there you have it: likely the first side mounted brushless DC powered, Nuvinci driven, LiFePo4 powered bike in the world and probably the last. Until, I resurrect it from my ebike grave yard!
BTW: I actually trucked this thing across the country literally and found what is rated to be one of the better MTB trails in the PNW and rode it up to the top.(Ape Canyon Trail) This is a whole 'nother story but I did abandon it in the woods somewhere above Smith Creek for several weeks when it stopped working. I did recover it.