Sealed Wheel Bearing and Shielded Wheel Bearing numbers are imprinted on both side covers of the bearing.

Sealed Wheel Bearing numbers end with RS or 2RS and have plastic side covers which make a positive seal to protect against dust and water intrusion. The side covers may be removed for inspection and re-lubrication and then reinstalled. Sealed wheel bearings typically outlast shielded wheel bearings because their plastic seals keeps out dirt and water.

Shielded Wheel Bearing numbers end with Z, ZZ, or 2Z and have steel side covers which protect the bearing against severe physical damage. Their steel side covers do not make a positive seal though so they do not protect the bearing against dust and water intrusion. If your electric scooter or bike needs bearings and currently has shielded wheel bearings you may want to consider switching over to sealed wheel bearings for a longer service life.

Bearing Installation: A bearing press or similar pressing tool should be used to exert the force needed to press the bearing into the wheels hub.

A Homemade Electric Scooter Wheel Bearing Press for installing sealed bearings into most aluminum electric scooter wheels can be made from an 8" long x 3/8" diameter machine bolt, four 3/8" fender washers, and a 3/8" nut. To use this tool place two washers onto the end of the bolt and insert the bolt in between the two sealed bearings and the hub. Then place two washers and the nut on the end of the bolt and tighten the nut and bolt together and carefully press the bearings into place. Care needs to be taken so that the bearings are started out straight and not at an angle to the hub.