I'm planning something similar-I just discovered a nice cheap Touring bike (single gear) and i'm going to take advantage of its mechanical simplicity by attaching a sprocket beside the wheel opposite the chain and running a second chain to the motor behind my seat. My choice of motor is a 12V, 50A Ghia generator-several local mechanics tell me the motor will withstand up to 2400+ RPM for an extended period, and at 24V it's going to max at 1200-so i'll also be foregoing expensive controllers for a controller/throttle box(a model railroad transformer rated at 24V and 120A, and i'll add a spring to the sliding lever for a deadman switch).
The bad news is i'm broke, so i'll be waiting a few weeks before I can grab some Lead Acid batteries rated at 12V 25Ahr-but at least I can use my 12V 13.5A charger so I won't have to buy one (and Balancing won't be a problem since I can only charge one at a time, mixed blessing there). Oh, you and I will both need a simple Voltmeter so we can read our 'tanks'.
The OTHER bad news is that I live in the Boonies, so my EV will be a toy at best, the nearest town is 11 miles away.
Still, I have everything but the Gears and Batteries just lying around, may as well put my theory to the test!
BTW, have you considered building a superlight Bike trailer and adding some extra packs in parallel for extra range? The Instructables website-
Instructables - Make, How To, and DIY
-has dozens of DIY Bike trailers, most of them created from somebody's latest dumpster diving session...i've made the PVC one already. Eventually, you and I might get the speed and range required to either get pulled over by the Cops or get run over by traffic...
Just to to be clear though-you finish your Project, you're gonna have to call yourself something else...
