Bikes and rattles often seem to go together. A common yet often overlooked culprit are the hub cones. On conventional hubs (that is, ones with loose balls inside them), the cones are the outer bearing surface and can be adjusted to take up slope. They can work loose, introducing play into the bearings and leading to a rattly wheel. You can check for loose cones by simply grabbing the top of the wheel and trying to move it sideways. If the rim moves and the hub axle doesn’t, the cones are probably loose. Confirm it by taking the wheel out and wobbling the axle – you’ll be able to feel any play.
Many aftermarket hubs use replaceable cartridge bearings instead of loose balls and adjustable cones. If these develop play it usually means replacing the bearings, although a few hubs can have the end-load adjusted.
If the cones are loose there’s a fair chance that the hub could really do with a strip, clean and re-grease, but for now we’ll just look at tightening the things back up to get you back out there…
1. Cones are very narrow and you’ll need special thin cone spanners to reach them. There are a few different sizes depending on what hubs you have. Shimano fronts are 13mm, rear 15mm. You may find it useful to have another spanner to hand to fit the locknuts – 15mm for the front, 17mm for the back.
2. Having established that you’ve got loose cones, take the quick release skewer out of the axle – it just gets in the way. Pop the spring and nut back on the shaft, they have a tendency to roll off under things.
3. Many hubs (including most Shimano ones) have a rubber seal covering the cones. Carefully lift this out with the aid of a small screwdriver. Mind you don’t damage it.
4. Now you’re at the cones. There’s a cone each side although generally you only need to adjust one side. They’re kept in place by locknuts, so the first task is to back the locknuts off the cones. Put your cone spanner onto the cone behind the locknut.
5. Then put another spanner on the locknut and turn it anticlockwise, holding the cone in place with the cone spanner. It should come undone. If it’s stubborn, position the spanners so that you can pull the two handles together in one hand.
6. With the locknut freed, you need to take up the slack in the cone. Put the locknut spanner on the locknut on the other end of the axle and tighten the cone against it. Don’t go mad, the axle’s still got to turn. Achieving the right adjustment is a question of trial and error. For now, take the slack out and tighten the cone just a little more, no more than a quarter of a turn.
7. To keep the cones in place they need to be snugged up against the locknuts. Tighten down the locknut on to the cone, and then hold the locknut in place and back the cone off against it.
8. Check for play in the axle. It should spin smoothly without rattles. You’re aiming for the tiniest, tiniest amount of play – putting the wheel back in the bike gives some extra end-load that you need to allow for. If there’s too much or too little, go back and readjust.
9. When you reckon you’re there, put the rubber seal back, replace the QR skewer and put the wheel back in the bike. Grab the rim and check for wobbles. If all’s gone according to plan, the wheel should spin smoothly and be wobble-free…