Sprocket

A sprocket,[1] sprocket-wheel[2] or chainwheel is a profiled wheel with teeth that mesh with a chain, rack or other perforated or indented material.

[3][4] The name 'sprocket' applies generally to any wheel upon which radial projections engage a chain passing over it.

The term 'sprocket' originally applied to the projection from the wheel that caught on the chain and provided the drive to it[citation needed].

The resulting lower gear ratios make the bike easier to pedal up hills while the higher gear ratios make the bike more powerful to pedal on flats and downhills.

With respect to the stock gearing on a motorcycle, installing a smaller counter-shaft sprocket (fewer teeth), or a larger rear sprocket (more teeth), produces a lower gear ratio, which increases the acceleration of the motorcycle but decreases its top speed.