This is a hub motor for gas-to-electric motorcycle conversions. The motor is built into the wheel, so there is no mechanical linkage; you just scrap the entire drivetrain and replace the rear wheel. Selecting and installing batteries is an exercise left for the reader, but this design removes a significant challenge from the conversion process.

It’s a small outfit – two brothers commercializing their hobby, from the look of it – but if they outsource the manufacturing there’s no reason they can’t produce a quality product at a reasonable price. It’s just a start, but it’s great to see this kind of thing becoming more practical.

Performance, of course, totally sucks – the EnerTrac specs suggest a top speed of “60+” – but the hub-motor design suggests that a hybrid bike might be practical. I can imagine adding a sprocket to one of these hub motors and installing it on a standard bike, then simply cruising around on battery power whenever low speeds and stoplights are involved. Using the electric motor for acceleration and the gas motor for cruising would save energy overall, without sacrificing speed, acceleration, or range. Assuming you’d purchase an off-the-shelf motor controller, the chief design problem would be the composition and location of the battery pack.

addendum: someone in Colorado has converted their FJ600 to electric power, using a more conventional chain drive setup. Top speed is 66 mph, using a 72-volt battery, but range is only 18 miles – nickel-cadmium is lightweight, but energy density sucks.

second addendum: Zero Motorcycles has announced an all-electric street bike, claiming availability next month at $10k. Specs are 60 mile range, 4-hour charge, 31-hp motor, 60 mph top speed. It may top out quickly but it’ll feel like a rocket getting there – that motor puts out 62.5 ft-lbs of torque, and the bike only weighs 220 lbs, so it will accelerate like nobody’s business. Fun, fast, reasonable commuter/errand-running range, no assembly required: $10k is high, but that’s to be expected for the first generation. The electric motorcycle era is much closer than I realized.