How to Repair Wheel Bearings
By Tim Brennan
Thanks to Leonardo Da Vinci, inside the hub of your bicycle wheels are lots of small steel balls. Their job is to keep the wheel rotating with minimal friction. Every few years, depending on use, these ball bearings get worn out, are no longer perfectly round and thus need replacing.
The best way of telling how your wheel bearings are is by listening and feeling for wobble. Turn your bike upside down and give your wheel a good spin if you can hear clicking noises that means the bearings are worn. Also, grip the rim of the wheel and see if it can be wobbled from side to side. If it does then either the wheel needs adjusting or more commonly new ball bearings.
Packets of ball bearings are not too expensive - they're around £2 for a bag of 20 or so. Remember to make sure that you get the right size - most wheels are normally a standard size. Whilst your at the shop you will need a tube of grease - should cost about £1-£2.
To replace the bearings follow this procedure:
- Turn your bike upside down.
- Some bikes have two wheel nuts and washers on the end of the wheel axle - if so these should be removed and put in a safe place. Others have quick release or allen key fixings - if so only one side needs un-screwing before the skewer can be removed and put to one side.
- The wheel should now be free to come off the bike. Some chunky tires may get stuck on the brake pads. If so unclip the brake cable at the caliper.
- The wheel axle has the following components attached to it:
Lock Nut~cone~Ball Bearings~Bearing Cup~wheel~bearing cup~Ball Bearings~cone~Lock Nut
It is only necessary to unscrew one lock nut and one cone to slide out the axle. When you do this use some paper to catch the old greasy bearings that will fall out. - Count how many ball bearings fell out of the wheel and this number will need to be replaced with the new ones.
- Apply plenty of grease to just the two bearing cups (these should be permanently fixed to the wheel hub).
- Pack the correct number of new ball bearings into one of the cups - insert the axle into the wheel so that the cone that you left on is now pushed against the greasy balls.
- Hold the axle firmly to retain the ball bearings and then fill the other with more grease and more balls.
- Screw the cone back on to secure the ball bearings, but don't over tighten. It should be finger tight and you should try to strike a balance between the axle rotating freely and it not moving when you wiggle it. Its a bit fiddley but after a few trial and errors you will get it just right.
- Next put the lock nut on to secure the cone in that exact position, then tighten it with a spanner.
- At this stage you might have moved the cone so check it again for wobble, give it a spin to see how free it moves and go back and readjust if necessary. Phew, I'm glad that bits over!
- Replace the wheel and if you unclipped the brakes before, put them back.
- Replace any washers that you removed and loosely tighten the wheel nuts. Check the wheel is in the same position as before by pressing the brake lever and making sure that the wheel is sitting in the middle of the brake blocks.
- When you are happy with the position of the wheel fully tighten it so it won't come undone by accident.
- Happy cycling!
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