The technology of a flywheel is simple and old: Use energy to spin up a wheel very quickly. Later, you can take that spinning energy and use it for something else. But you normally think of flywheels as enormous steel monstrosities spinning in factories. But 22-year-old inventor Maxwell von Stein's new bike employs a small flywheel to boost his speed and take a load off his legs while pedaling:
When braking, the biker simply shifts gears and allows the energy to transfer from the back wheel to the flywheel (instead of transferring uselessly to the brake pads). Once the rider wants to accelerate again, he simply shifts the gear and the flywheel transfers that power back to the bike, sending the cyclist on his merry way.
The wheel weighs 15 pounds, so you certainly need the extra help it provides to keep moving. But, as the simple flywheel makes a comeback in all sorts of applications, Stein's invention shows that even the bicycle can get a boost from the the technology. Just don't reach down looking for your water bottle. You're liable to lose a finger.