How To Insert Skateboard Bearings

If you think it's time to replace your skateboard bearings, or even if you're just cleaning your old bearings, you'll need to know how to insert them when you're done. Skateboard bearings can be a tight fit, and you'll need to apply some pressure in order to insert them. But be careful; inserting your bearings improperly could damage them.

1. Remove the wheels from your skateboard. If you're assembling your skateboard for the first time, of course, you won't need to do this. However, if you're cleaning or replacing bearings, you'll first need to remove your skateboard wheels by loosening the nuts that hold them onto the axles. Use a ratchet wrench or skate tool.
2. Once you've got the wheels off, pop out the bearings. You can use the end of your skateboard axle. Just stick it into the hole in the middle of your bearing and pry gently outward. The bearing should pop out easily.
3. Insert new bearings. If you're cleaning your old bearings, you'll go through that process first. If you're assembling your skateboard for the first time, you'll start here. Press the bearings into the center of the wheel with your fingers. Skateboard bearings fit snugly, so you may need to use a large socket on your ratchet wrench to press the bearings in securely; apply pressure around the outer edges of the bearing only, since pressing on the center of the bearing or on the bearing shield could damage it.
4. Reattach your wheels to your skateboard. Tighten the nuts until your wheels no longer move from side to side on the axle, but not so tight that your wheels can't spin freely. 

Reference:

How to fix skateboard bearings