RevoPower: Reinventing The Wheel Literally (Link)

What a clever idea and a power capability to add to your bicycle to help you to continue "moving" in case you're tired or you don't want to pedal anymore!

All you have to do is simply slide a canister of gasoline into your water-bottle holder, clip a throttle to your handlebars, and swap your front wheel for the Wheel, designed by Denver-based RevoPower.

The Wheel’s hub holds a 23cc, two-stroke internal combustion engine and a superthin gear train; less than three inches thick, it all fits between the prongs of your bike’s front fork. Start pedaling and squeeze the throttle, and the engine kicks in, rotating the wheel around its fixed axle and boosting your power. Let the throttle go, and you can keep pedaling as usual.

Good advice from (Popular Science) website, just remember two things: Bring your driver’s license (the engine may trigger regulations in some states), and don’t drink from the water bottle.

Revpower Wheel Specs
Size: 26 in.
Weight: 15 lbs.
Speed: 20 mph
Power: 1.1 horsepower
Efficiency: 200 mpg
Price: $400; available in early 2007

Read Also:
Pedaling is So 2005 (Popular Science)
The Wheel turns your bike into a moped (Engadget)