Belt-driven bicycle with a compact design that, like STRiDA, featured a belt drive. Other folding-bike manufacturers that have implemented a belt drive include U.S. company Bike Friday and Netherlands-based Bernds. In 2007, Gates Corporation developed a high-modulus synchronous belt and sprocket system called the Carbon Drive System. The belt’s pitch allowed for lower tension requirements to help prevent skipping. Lightweight, patent-pending sprockets have mud ports, openings under each tooth, which work to slough off debris. In 2009, an increasing number of bicycle companies, including Trek and "f"8 Cycles, offered belt-driven bicycles. While builders initially focused on single-speeds and internal hubs, in early
Bicycle fork intended by the frame designer. The functional length of the fork is typically expressed in terms of Axle-to-Crown race length (A-C). Also, the axle on the wheel must fit in the fork ends (usually either a 9mm solid or hollow axle, or a 20mm thru-axle). Some manufacturers have introduced forks and matching hubs with proprietary standards, such as Maverick's 24mm axle, Specialized 25mm thru-axle and Cannondale's Lefty system. Fork steerer tubes may be threaded or unthreaded, depending on the headset used to attach the fork to the rest of the bicycle frame. An unthreaded steel steerer tube may be threaded