Know Your Bearing...
As the distributors for Various Bearings, people ask us all the time "what do the bearing codes mean?" or "what does the 2RS stand for?". Well, bearing manufacturers don't simply use these numbers to confuse you, they actually use these numbers to categorise bearings in a way in which from a glance its easy to know what a hearing is typically used for, how robust it is, and if its suited to the application its intended for. Whats even better, is that if used properly, these codes transcend manufacturers, so if you're looking for a
bearing and have the standard code it doesn't matter what the make is. Here is a little quick reference guide that explains these bearing codes in detail.
Lets use a 6902 as an example:
S 6902 2RS ^ ^^^^ ^^ Prefix Code Suffix
K - Cage with roller elements
L - Removable bearing ring
R - Ring with roller set
S - Roll body of stainless steel
W - Stainless steel deep groove ball bearing
(6)902 - This first number relates to the bearing type, typically most bicycle bearings will be a “6” which is a “Deep Groove”. Occasionally you will find a “7” bearing which is a “Single Row Angular Contact”
6(9)02 - This second number relates the bearing series, which reflects the robustness of the bearing. As you go up the scale below from 9 to 4 the inner and outer race thickness will usually increase along with the ball size, this will be to help cope with extra load.
9 - Very thin section
0 - Extra light
1 - Extra light thrust
2 - Light
3 - Medium
4 - Heavy
69(02) - The 3rd and 4th digits of the bearing number relate to the bore size of the bearing, numbers 00 to 03 have a designated bore size depending on the number.
00 - 10mm
01 - 12mm
02 - 15mm
03 - 17mm
*Note: Numbers over 03 simply have a bore size which is 5 times that of the 3rd and 4th digit.
2 RS - Bearing with rubber seal on both sides. RS provides a better seal but more rolling friction than 2Z.
RS - Bearing with rubber seal on one side, one side open.
2 Z / ZZ - Bearing with a metal seal on both sides.
Z - Bearing with a metal seal on one side, one side open.
E - Reinforced Design
P2 - Highest precision
K - Bearing with taper bore