A type of rear hub that contains a ratcheting mechanism and accepts a cassette rather than a freewheel.

A freehub is a bicycle rear axle assembly that incorporates a ratcheting mechanism. Separately, a set of sprockets (called a "cassette") are mounted onto a splined shaft on the freehub. In contrast, a freewheel contains both the chain gear cogs and a ratcheting mechanism in a single unit.