Maybe you just got a new fork. Maybe you’ve decided to remove some spacers and lower your riding position. Either way, you’ll likely need to trim at least a few millimeters from your fork’s steerer tube. It’s a fairly simple procedure, but not one you can start over if you mess up (if you know what we mean). To avoid any costly mishaps, watch this video first.
To complete the steerer tube trimming process, you’ll first need to remove your fork from your bike. Check out this video, which explains that simple procedure, and details the steps required to swap out and grease headset bearings.