The hub is the core of a wheel, since it’s where the spokes sit from the rim while staying bolted to the fork and allowing the free rotation of the wheel.

Key points:

· Axle spacing: it’s usually 100mm, except for some very particular models (e.g., some 70mm-wide Monty kid hubs). · Axle diameter: 9mm in most cases.

· Spoke holes: usually 28 holes (28H), although some have 32 holes (32H).

· Rotor mounts: a front hub might or might not have standard 6-bolt rotor mounts.

· Bearings: sealed bearings are more reliable and durable than open bearings.