You’re not missing anything- you can knock the new bearing into the hub with a block of wood, then the shaft goes into it and is tightened by the bearing ring nut. Easy with the right tools. If you have a shielded bearing and sometimes they come that way, you can pop out the shield on the side that faces outboard with a small screwdriver so the bearing gets the proper grease load. The inboard facing shield can stay.
Anonymous