With gas prices at alltime highs, engineers at RevoPower Inc., Denver (revopower.com), decided the market needed an alternative. Electric bikes tend to be heavy and limited by battery performance, so they developed a new twist on the moped, the Wheel. It's a 26-in. wheel for the front of a bicycle and carries a 25-cc two-stroke engine with an output shaft turning at 7,500 rpm. A series of gears form a transmission that drives the wheel and engine about the front axle of a standard bike. The Wheel weighs about 15 lb and gets 240 mpg.

Although EPA regulations do not apply, the company says their Wheel will meet ultralow emission standards. The entire motor and exhaust are contained in a 14-in. hub that does not interfere with normal bike operations. Users can pedal the bike normally or engage the Wheel by pushing on the handlebar throttle. Steering is unaffected by the motor. And if bike speed exceeds the Wheel capabilities (about 20 mph), the motor disengages from the drive.

Installation takes only minutes and requires no special tools. The company plans on selling a complete, ready-to-ride motorized bicycle ($800 to $1,000), or just the front wheel ($600).