Belt-drive bikes use a reinforced toothed polymer belt in place of a chain. Belt-drives are paired with a single speed or internally-geared rear hub.
Because the belt is a continuous loop that can't be opened to remove it, the frame of the bike is built with a cut-out (frame lock) on the chain stay that can be opened to pass the belt through. The belt is then looped over the rear sprocket and the belt is tensioned in the same fashion as the chain on a single-speed bike.
Belt drivetrains are expected to be longer-lasting and lower maintenance than chain, especially more than derailleur-based set-ups. Because belt drives are not compatible with derailleurs, an internally-geared hub (IGH) is required to provide gears.