I really like my Razor electric dirtbike, it would be so much nicer if it had a greater range than 10 miles to a 4 hour charge. Electric bikes can get finicky if you modify them like I have, and you really gotta use the new lightweight batteries. The problems mine has are weight and breaking stuff because of weight and big torque. Mine has the stock SLA's and they weigh about forty pounds plus about ten pounds of supercaps. The torque is enough to make the motor slide in its solidly bolted mounts, had to use a hose clamp to hold tension on it.
I am too very fascinated by electric bikes and the endless possibilities, the price of batteries needs to come down though. Once the next generation batteries that don't use lithium are made, the LiFePO4 packs will get sold at a discount, and the new batts will be cheaper unless they choose to uprate the specs for all batteries to keep them expensive - something that a lack of competition will definitely cause. It really sucks that the options for the affordable batteries are so slim, and I don't trust how they are assembled, or the BMS packs they provide for the cheaper "duct tape" or "shrink wrap" packs. The best idea is probably to become an expert in pack configuration and battery leveling circuits, buy a bunch of cells, and build your own pack to fit your frame.
Call me a cheap ass, but it's hard to justify spending $500 on a 48v 20ah pack when I could go 10000 miles on a gas bike for the cost of the energy storage device. I'm trying to be content with my dinosaur of an electric bike, and wait until I can afford to do it right, because the technology for a 100mph electric scooter exists right now but its just so awfully expensive.
A good way to have fun with electric bikes and be cheap like me is to check out electric recreational scooters, dirtbikes, and pocket bikes. The technology on these bikes is ancient, but the parts are affordable. The stuff that's made officially for Razor is of high quality, I haven't been disappointed with any of their electronics. SLA batteries can be bought for $20 each for a 12v 7ah cell. They suck for bicycles, but if you were creative I bet 36V worth of lead juice could be hidden under a fairing or tank. I think 36v is really all you would need on a pedal bicycle for cruising, maybe 750-1000W max, and it would equate to a happy time motor.
The quietness is so nice, it makes cruising around really relaxing. Horses get insanely spooked by the still somewhat noisy chain drive and motor whine on my dirtbike though, I'm afraid one of those rich little ladies is going to sue me after getting dumped off their skiddish horsey because it goes catatonic. My gas bike never screwed with the horses like this, it's strange.