The bike hub is the core component of a bicycle wheel, located at the center of the wheel and connected to the rim through spokes to form an integrated structure. Its shell is typically made of steel alloy or aluminum alloy, and an internal bearing system is used to reduce rotational friction. The rear hub integrates a freehub body for mounting the cassette and enabling ratchet-driven power transmission. Modern hubs adopt a modular design and include standardized interfaces—such as six-bolt mounts and center-lock rings—to accommodate disc brake systems.
Based on transmission principles, hubs can be classified into single-speed hubs, derailleur hubs, and internal gear hubs. Among them, derailleur hubs adjust rotational speed by changing gear engagement. Patent technologies indicate that hub assemblies use an internal spline engagement structure to transmit driving force, with surface angle parameters controlled within a range of 0°–60° to achieve optimal transmission efficiency. During maintenance, specialized tools are required for freehub removal and bearing replacement.