After a couple years of installing bearings, here are a few tips that I've learned to help reduce headaches related to this process. You're going to have to do this often for your kid and his friends, so you better learn how to do it sooner rather than later.

The series of numbers in front of the bearing name can provide much information about that specific type of bearing. Here is an example:6001ZZ

6 = Type Code

0 = Series

01 = Bore Size

ZZ = Suffix

Type Code Definitions:

1 - Self-aligning ball bearing

2 - Wide self-aligning ball bearing

3 - Double-row angular contact ball bearing

4 - Double-row ball bearing

5 - Thrust ball bearing

6 - Single-row deep groove ball bearing

7 - Single-row angular contact bearing

16 - Thin section single-row deep groove ball bearing

22 - Self-aligning roller bearing

23 - Wide self-aligning roller bearing

Series: (Identifies the lightness or heaviness of the skf bearing)

0 - Extra Light

1 - Extra Light Thrust

2 - Light

3 - Medium

4 - Heavy

7 - Not Sure

8 - Extra Thin Section

9 - Very Thin Section

Bore Sizes (in mm):

For most ntn bearings, the bore size can be calculated by adding the 3rd and 4th digits together and multiplying the result by 5. However, there are a few exceptions to this rule, as follows:

00 = 10 mm

01 = 12 mm

02 = 15 mm

03 = 17 mm

Suffix Meanings:

Z - Single Shielded

ZZ - Double Shielded

RS - Single Sealed

2RS - Double Sealed

V - Single Non-contact Seal

VV - Double Non-contact Seal

DDU - Double Contact Seals

NR - Snap Ring and Groove

M - Brass Cage

C3 - This marking indicates a radial internal clearance greater than the standard clearance. C3 bearings are usually fitted to equipment where there are large temperature differences between the inner and outer casings, therefore, sufficient clearance is needed to avoid early bearing failure.

In addition to using grease for packing headset bearings, I also like to use a little grease to help ease the friction between [scooter bearings] and metal core wheels during installation. Just dip your finger in the grease and put a light coating around the inside of the wheel's core where the outer ring of the bearing will make contact. It doesn't take much, so don't over-do it.