A bike wheel is a complex assembly of different parts that work together to support your ride. See below for a summary of the parts that make up a bike wheel, including rim tape, spokes, valve caps, axles, hubs, rims and skewers.
Rim tape: Rim tape is a thin strip of material covering the rim's inner surface. It protects the inner tube from punctures caused by sharp edges or holes in the rim. Rim tape can be made of rubber, cloth or plastic. Some rims have a built-in rim strip that does not require additional tape.
Spokes: Spokes are thin metal rods that connect the hub to the rim. They provide tension and strength to the wheel and help distribute the load evenly. Spokes can be straight or butted (thinner in the middle), round or bladed (flat), and have different patterns such as radial (straight from hub to rim) or crossed (interlaced). The number and arrangement of spokes affect the wheel's weight, stiffness and aerodynamics.
Valve caps: Valve caps are small plastic or metal covers that screw onto the inner tube's valve stem. They protect the valve from dirt and moisture and prevent air leakage. Valve caps can also add style to your wheels with different colours and shapes. Some valve caps have built-in indicators that show if your tyre pressure is too low or high.
Axles: Axles are metal rods that run through the hub and attach to the frame or fork via dropouts (slots). They allow the wheel to spin freely around them while transferring power from the pedals or brakes to the wheel. Axles can be solid or hollow (quick release), threaded or smooth, and have different diameters depending on your bike type and standard.
Hubs: Hubs are cylindrical parts that house the axle, bearings and freehub (or freewheel) mechanism. They are located at the centre of each wheel and connect to the spokes via flanges (protruding parts with holes). Hubs allow the wheel to spin smoothly around the axle while engaging the drivetrain when pedalling or disengaging it when coasting backward. Hubs can have different numbers of spoke holes, bearings types (sealed cartridge or loose ball), freehub types (cassette or screw-on) and engagement points (ratchet teeth).
Rims: Rims are circular metal parts that form the outer edge of each wheel. They provide support for the tyre and brake surface for the brake pads (if using rim brakes). Rims can be made of aluminium alloy, carbon fibre or steel, and have different widths, depths, shapes, weights and finishes depending on your riding style, tyre size, brake type and preference.
Skewers: Skewers are metal rods with levers at one end and nuts at the other that secure the wheels to the frame or fork via dropouts. They replace solid axles in quick-release systems, which allow you to remove and install your wheels without tools. Skewers can be made of steel, aluminium alloy, titanium or carbon fibre and have different lengths, diameters, weights and lever designs depending on your bike type and standard.