Gears and Gear Ratios

Gears are wheels with teeth that interlock to change the speed or force of movement. When a small gear turns a larger one, the larger gear turns more slowly but with more force. When a large gear turns a small one, the small gear spins faster.

Bicycles use gears so that riders can climb hills more easily by changing the gear ratio. A low gear makes pedalling easier, while a high gear helps you go faster on flat roads.