The Complete Handbook of Bicycle Hubs

Chapter 1: Understanding Bicycle Hubs

The Hub: More Than a Spinning Core

A bicycle hub is the central rotating assembly of a wheel. It is what allows the wheel to spin around a fixed axle, and it is the critical interface between the static frame or fork and the dynamic rim and tire. Strip away the spokes, the rim, and the tire, and you are left with the hub: a body that rotates, an axle that stays still, and bearings in between that manage the enormous forces of riding. That is the whole system, but every part of that system has to be engineered for the specific job it does. A cheap hub that works fine for a 60-kilogram commuter on smooth asphalt can be a dangerous failure point on a loaded touring bike or a competitive cyclocross bike.

To understand a hub, start with its three main parts. First is the hub shell, the external body that spins. It typically has flanges — circular raised lips — onto which the spokes are threaded and tensioned. Second is the axle, which does not spin. It is the part the frame grabs onto via a drop-out, a quick-release skewer, a thru-axle, or a bolt. Third are the bearings, sitting between the shell and the axle, allowing the shell to rotate with minimal friction while supporting the weight of the bike, rider, and gear. That is the simple version. From here, everything expands in the direction of weight, cost,