You are measuring the wrong part of the fork. The steerer is actually inserted into and welded to the section you are measuring. To measure the steerer you have to expose it. To do this you have to remove the top bearing and let the fork drop out of the frame. The bottom of the steerer has a short widened section onto which the crown race is friction-fit. Measure above this section. Use a caliper. You can buy a good cheap one at Home Depot or Ace. My money says this is a 1" steerer, (25.4 mm) with a 22.2 mm inside diameter.
Last edited by oldbobcat; 09-22-22 at 08:08 PM.