Originally Posted by
Barry2
At the bottom of the steerer there should be a “crown”, it is a taper, often a metal washer or a taper in the carbon, with a taper that narrows at the top.
As the lower bearing is forced down onto this taper (crown), it centers the fork. Notice the lower bearing is also tapered on the bottom to match the taper on the fork.
The fork crown is the part that connects the legs to the steerer (with most unicrown forks the crown is reduced to a sleeve fitted over the steerer, although there are a few unicrown forks with a lugged crown).
The part of the crown where the headset crown race fits is the crown race seat, conical on some forks, a cylindrical interference fit on others.