How does a standard bicycle transfer pedaling power to the rear wheel?

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An African American family of four, all wearing helmets, rides bicycles together on a tree-lined country trail, with two children in front and two adults following behind. — bicycle Family bicycling on a country road.

A standard bicycle transfers power from the rider's legs to the rear wheel primarily through a chain drive system.1

When a rider pedals, they rotate the crank, which is connected to a front chainwheel. This motion pulls the chain, which in turn rotates a rear sprocket attached to the rear wheel. By utilizing different sizes of chainwheels and sprockets—often managed by derailleurs—the rider can adjust the gear ratio to change how many times the rear wheel turns relative to each rotation of the pedals, allowing for efficient travel across varying terrain.1