Rubbee consists of a polyurethane roller wired to a 14.4-volt battery pack. The doohickey presses the roller against the back tire of the bike, propelling it with the force of wheel-on-wheel friction. The rider controls the wheel speed via a handlebar-mounted throttle, and can "flip" the little wheel away from the back tire once they want to go au naturel. As it is, the company says Rubbee can supply 15 miles of pedal-free riding on a single charge.
Speaking of charges, there's no retail price for the Rubbee, but you can be the first on your block to have one by way of a $1,200 pledge to the company via Kickstarter. In the meantime, check out the 50-second video below to see how Rubbee works.