Pyörännapa

Pyörännapa is the central part of a bicycle wheel. It houses the bearings that allow the wheel to rotate and is the component to which the spokes are attached. The hub also contains the axle, which connects the wheel to the bicycle frame. On the rear wheel, the hub typically includes the freehub body, which is where the cassette of gears is mounted. This freehub mechanism allows the pedals to remain stationary while the wheel continues to turn, a crucial feature for freewheeling. Hubs can be made from various materials, including aluminum alloy, steel, and sometimes carbon fiber for high-performance applications. Different types of hubs exist, such as those designed for quick-release skewers, thru-axles, or even for specific braking systems like coaster brakes or disc brakes. The engagement mechanism within the freehub is responsible for transferring pedaling force to the rear wheel. The quality and design of a bicycle hub significantly impact the efficiency, durability, and overall performance of the bicycle.