Cup-and-cone bearings are systems where ball bearings sit inside a metal cup, trapped in place by a cone that threads onto the wheel axle.

The cup is typically an intrinsic part of the hub and though some can be removed, it is not standard practice as manufacturers such as Shimano do not recommend it as part of hub servicing.

The ball bearings either sit inside a cage which keeps them equidistant from one another, or loose inside the cup.

The hub will be packed with grease from factory to allow the bearings to roll smoothly against the cup with minimal friction.

Bearing tightness is determined by how closely the cone holds the bearings against the hub. It’s adjusted by moving the cone along the axle thread and securing it with a lock nut.