Bike wheel parts at a glance
A bicycle wheel looks simple, but it is a small structure made of several parts that depend on each other. From the center outward, a typical spoked wheel has:
- An axle, which connects the wheel to the frame or fork.
- A hub, which holds the bearings and gives the spokes something to attach to.
- Spokes, thin rods that connect the hub to the rim.
- Nipples, small threaded fittings that hold the spoke ends at the rim and let you adjust tension.
- A rim, the metal or carbon ring that supports the tire.
- A tire, usually with an inner tube or a tubeless setup, and a valve for inflating it.
The rear wheel adds a few extras, such as a freehub body for the cassette and, on many bikes, a mount for a disc brake rotor.
The hub (the thing in the middle)
The part in the middle of a bike wheel is the hub. It spins around the axle on bearings, and it has two flanges (raised discs or rings) with holes where the spokes attach. Front hubs are fairly simple. Rear hubs are more complicated because they also have to drive the chain through a freehub. For a closer look, see our bike hub diagram and parts guide, and for the bearings inside, see bike wheel bearing sizes.
The rim
The rim is the outer ring of the wheel. It holds the tire, and on rim-brake bikes it also provides the braking surface. Rims are most often aluminum or carbon fiber. The inside edge has holes for the nipples, and many rims have a hole for the valve. Rim width, depth and internal shape vary quite a bit, and they affect tire choice, weight and ride feel.
Spokes and nipples
Spokes are thin steel (sometimes other material) rods that run between the hub flanges and the rim. Each spoke is held under tension. The nipple is the small threaded piece at the rim end of most spokes, and turning it changes the spoke’s tension. This is how a wheel is trued, meaning adjusted so it spins straight.
The number of spokes and the way they cross each other is called the lacing pattern. Common choices are covered in our guide to bike wheel lacing patterns.
Tire, tube and valve
The tire is not strictly part of the wheel structure, but most people think of it as part of the wheel. It sits on the rim, either with an inner tube or tubeless with sealant (see the tubeless sealant guide). The valve is how you add air. The two common types are Presta (narrower, with a small locking nut) and Schrader (similar to a car valve); see Presta vs Schrader for how to tell them apart. For the tire itself, the anatomy of a bike tire covers every part. Your rim’s valve hole needs to suit the valve you use.
Axle and quick release or thru-axle
The axle holds the hub bearings and connects the wheel to the bike. Wheels are secured with a quick release skewer, a thru-axle or, on some bikes, bolts. These are not interchangeable between bikes, so it is worth knowing what yours uses. See bike wheel axle types for details.
Extra parts on the back wheel
- Freehub body: the ratcheting part that the cassette slides onto. It lets you coast without the pedals turning.
- Cassette: the set of rear sprockets, mounted on the freehub.
- Disc rotor mount: a six-bolt or center-lock fitting on disc-brake hubs. Front wheels on disc bikes have this too.
Rim vs wheel: what is the difference?
A rim is only the outer ring. A wheel is the whole assembly: hub, spokes, nipples and rim (usually sold without tire). A pair of wheels sold together is a wheelset. When a shop talks about a “rim replacement”, they usually mean rebuilding the wheel around a new rim, reusing the hub and often the spokes.
How the parts work together
A spoked wheel works because of tension. The spokes pull the rim toward the hub from all directions, and the rim holds them in place. When you sit on the bike, the load is carried mostly by reducing tension in the spokes near the ground rather than by the spokes “pushing” up. Because of this, even tension between spokes matters. Uneven or very low tension can lead to wobbles or broken spokes. If you want to see how all of these parts are assembled, read how to build a road bike wheel.