The bicycle has two lead-acid batteries mounted near the rear wheel that provide electricity to a motor when commanded by a throttle resistor mounted on the handle bars. The motor is mounted on the bottom of the frame just in back of where the rear dropout normally is. The electric motor drives the rear wheel through belt and chain drive to a separate freewheel that is located on an intermediate shaft. This freewheel keeps the motor from spinning when the bike coasts (and the motor is off) or when you are pedaling and don't want to have the extra motor drag. There is another freewheel on the intermediate shaft for the chain coming from the pedals. This lets the motor run while the pedals remain stationary, a necessary and comfortable feature.

One nice feature of having the motor drive the wheel through the regular chain is the ability to shift the speeds of the motor using a standard rear chain cassette. The current design has six different motor gearing speed options in addition to the variable throttle control to the motor. This gives excellent control over a very wide range of speeds from 4 mph to 27 mph.

The extra length of the bike was added in order to mount the intermediate shaft, batteries, and motor drive. I opted to extend the frame and keep the front frame standard and the center of gravity low instead of stuffing all of the hardware higher up on the standard frame and having it get in the way of normal pedaling. This has obvious consequences for maneuverability and parking but it was an engineering tradeoff. The main drawback is the difficulty of making extremely tight radius turns when nearly stopped. The whole assembly is also considerably heavier than a "regular" bicycle. I would estimate 60 pounds. In any case it's very difficult to carry up and down stairs!

Despite the weight and size, the acceleration is very good. When starting out there is a strong kick and you can accelerate to 20 mph in just a few seconds. Everyone who tries it out comes back smiling. :)