Cycle your way out of traffic jams and high fuel costs—without breaking a sweat. 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 (revopower.com). 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.