The headset is the bearing on which the forks of the bike turn, allowing the bike to go round corners. An Aheadset is a particular type of headset which involves a threadless sheerer tube. Virtually all modern bicycles are fitted with a threadless Aheadset.

Fitting an Aheadset can be tedious as there are so many parts to it and they have to be put on in the correct order. If the headset is not put together correctly, it is likely to be damaged.

With most headset bearings, the bottom bearings have a greater diameter than the top bearings.

Drag the parts below onto the forks in the correct order: