A sprocket is a gear with metal teeth that mesh with a chain. Sprockets are used in bicycles, motorcycles, cars, and other machinery. By varying the size (and therefore, the tooth count) of the sprockets on each side of the chain, you can modify the overall gear ratio of the chain drive. By providing two different-sized driving sprockets and five different-sized driven sprockets, a 10-speed bicycle uses this theory to allow up to ten different gear ratios. The resulting lower gear ratios make the bike easier to pedal up hills while the higher gear ratios make the bike faster to pedal on flat roads. In a similar way, manually changing the sprockets on a motorcycle can change the characteristics of acceleration and top speed by modifying the final drive gear ratio.

Sprockets are used in the film transport mechanisms of movie projectors. In this case, the sprocket wheels engage perforations in the film stock.

Sprockets in Humor

The fictional character George Jetson works for the Spacely Sprocket Company, a company that presumably is involved in the production of space-age sprockets. What these sprockets drive is left to the imagination of the viewer.