Headset
frame
The headset is the bearing assembly that allows the fork (and therefore the front wheel and handlebars) to rotate inside the frame's head tube. It sits at the top and bottom of the head tube.
Modern headsets are mostly:
- Integrated — bearings sit directly in the frame's machined cups.
- Semi-integrated (zero stack) — cups are pressed into the frame, bearings sit inside the cups.
- Threadless — the standard for most modern bikes; no threaded steerer.
Headset standards vary by frame and fork. Common variations include 1-1/8" upper / 1-1/8" lower, 1-1/8" upper / 1.5" lower (tapered), and various integrated standards.
A loose or worn headset causes a knocking feeling under braking. A too-tight headset makes steering stiff. Periodic adjustment and cleaning are part of normal maintenance.
