SANBURG BEARINGS

 

Know the basics

A bearing is any surface that moves against another, part of a system that guides and supports a moving part. In bikes bearings reduce friction, heat and minimise power loss by letting components move freely against each other. A bike’s bearings also protect, wearing out rather than allowing a more expensive part to be damaged. In order to fulfil these duties many bearings need regular inspection and occasional adjustment or replacement to keep everything spinning sweetly.

Wheel bearings

Worn wheel bearings will have all kinds of detrimental effects on handling. They can be checked with the wheel in situ by giving them a quick wiggle to and fro, feeling for any side-to-side play. It is, however, easy to misinterpret slackness at the headstock or fork bushes (front) or swingarm bushes (rear) as wheel bearing play.

So if in doubt, remove the wheels for a more detailed inspection – and check them every time you have a wheel out as a matter of course. Stick your finger in the bearing’s inner race and feel for any play or ‘grittiness’. If there’s any of either, have the bearing replaced because once a high speed bearing starts to deteriorate, it will fail imminently.

Headrace bearings

Are checked by grasping the forks and feeling for front/rear movement, with the front wheel off the ground. If you feel play in the bottom of the forks then it may be that the fork’s sliding bushes are worn, so next grip the upper fork to isolate where the play lies (be sure the bike’s not just wobbling on its stand).

In many cases it’s possible to adjust play out of the bearings, but if they are damaged – most commonly this can be identified by the steering ‘centering’ – they must be replaced. The removal and replacement of bearings can be tricky and correct adjustment is critical. It’s easy to cause expensive damage to the frame, or leave your bike handling like a pig, so consult a manual before taking on the job.

Swingarm bearings

Grip the swingarm and try to move it side-to-side. Again, it’s easy to mistake wobbling on a stand for play in the bearings. Some swingarm bearings/bushes can be adjusted; others will need replacement, so check a manual.

Suspension bearings

With the back wheel off the ground, lean over the seat and try to lift it. If it rises any distance with no resistance from the shock, then one or more linkage bearings is likely to be shot and more investigation is required.