Flip-flop hub - Both sides of the hub are threaded, allowing the wheel to be removed and reversed in order to change which gear is used. Depending on the style of threads, may be used with either a single speed freewheel or a track sprocket. Internal geared hub - the mechanism to provide multiple speeds is contained inside the shell of the hub. Many three-speed internal geared hub bicycles were built in the last century. This is an extremely robust design, although much heavier than more modern designs of multi-speed arrangements. Modern hubs are available from three-speed to 14 speeds or a continuously variable transmission hub.
Originally a wooden structure, today the bicycle wheel rim is typically either a carbon fiber structure or, more commonly, a metal extrusion that is butted into itself to form a hoop. Some wheels use both an aerodynamic carbon hoop bonded to an aluminum rim on which to mount conventional bicycle tires. Metallic bicycle rims are now normally made of aluminium alloy, although until the 1980's most bicycle rims - with the exception of those used on racing bicycles - were made of steel. and thermoplastic. Rims designed for use with rim brakes provide a smooth parallel braking surface, while rims meant for use with disc brakes or hub brakes sometimes lack this surface.
The Westwood rim is designed for use with rod-actuated brakes, which press against the inside surface of the rim. These rims cannot be used with caliper rim brakes. The cross-section of a rim can have a wide range of geometry, each optimized for particular performance goals. Aerodynamics, mass and inertia, stiffness, durability, tubeless tire compatibility, brake compatibility, and cost are all considerations. Aluminum rims are often reinforced with either single eyelets or double eyelets to distribute the stress of the spoke. A single eyelet reinforces the spoke hole much like a hollow rivet. A double eyelet is a cup that is riveted into both walls of a double-walled rim.
Originally a wooden structure, today the bicycle wheel rim is typically either a carbon fiber structure or, more commonly, a metal extrusion that is butted into itself to form a hoop. Some wheels use both an aerodynamic carbon hoop bonded to an aluminum rim on which to mount conventional bicycle tires. Metallic bicycle rims are now normally made of aluminium alloy, although until the 1980's most bicycle rims - with the exception of those used on racing bicycles - were made of steel. and thermoplastic. Rims designed for use with rim brakes provide a smooth parallel braking surface, while rims meant for use with disc brakes or hub brakes sometimes lack this surface.
The Westwood rim is designed for use with rod-actuated brakes, which press against the inside surface of the rim. These rims cannot be used with caliper rim brakes. The cross-section of a rim can have a wide range of geometry, each optimized for particular performance goals. Aerodynamics, mass and inertia, stiffness, durability, tubeless tire compatibility, brake compatibility, and cost are all considerations. Aluminum rims are often reinforced with either single eyelets or double eyelets to distribute the stress of the spoke. A single eyelet reinforces the spoke hole much like a hollow rivet. A double eyelet is a cup that is riveted into both walls of a double-walled rim.
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