Stoke Monkey is a electric power-assist unit that fits on a extra long chain-stay bike, such as a bike equipped with an Xtracycle setup. It works by a variable-speed throttle on the handlebar and a tandem-like drivetrain setup. Once the motor is on, the rider would have to pedal along (like a tandem stoker). They claim a cruising speed of 30 mph on the flats.
To the right is a Sycip longbike equipped with a Stoke Monkey.