Ah, the humble spoke. A bike component of such little significance to most riders that it barely even registers as a component. Just the things that hold the rims to the hubs. It is the misfortune of the spoke to have no moving parts, not to be available in a range of anodised colours and to only be made out of one material. OK, there are titanium ones but no-one uses them (and rightly so) so they don’t count.
But despite their low public profile, spokes are desperately important. How far would you get without any? Exactly. Which makes a spoke breakage something to be dealt with urgently. A word here about what it is that makes spokes break. You may think that they break from hitting things too hard, but that’s not really the case. They actually break from fatigue. As the wheel goes around, the spokes change tension. If there’s sufficient load on each spoke they’ll gradually fatigue and eventually break. If you (or your bike) is heavy or you carry a lot of luggage or there aren’t many spokes and you cover a lot of distance, you’re more likely to suffer spoke breakages.
Usually, if a spoke breaks it’s in the back wheel, because back wheels carry more weight and are subjected to more tension-varying impacts than front ones. Furthermore, because most rear wheels are dished, most of the loads are taken through the drive-side spokes so it’s usually one of those that breaks. From all of this you can probably see that if one spoke breaks there’s a few others not far behind…
If a spoke breaks it’ll be at a weak spot. Generally they’ll break at the elbow where they go into the hub, or less often at the threads in the nipple. Sometimes drive-side spokes will break a little way up from the hub, usually because at some point the chain’s gone over the big sprocket into the wheel and taken a gouge out of the spokes.
That’s enough background. Here’s how to sort it.
1. You’ll be needing a spoke key and a screwdriver. A wheel truing jig is handy if you’ve got one. Oh, and a new spoke of course. Your bike shop should be able to tell you what length you need if you tell them what hub and rim you’re using.
2. The first thing you need to know is what to do when the spoke actually breaks. They don’t often break just sat in the shed, you’re usually out riding when it happens. It’s a good idea to get them out of the way. If it’s broken at the elbow, you can undo the spoke nipple and just pull the spoke out.
3. If the spoke broke at the threads, you’ll have to unthread it from the hub. You’ll only be able to do this if there aren’t any disc rotors or rear cassettes in the way. If there are, either twist it around a neighbouring spoke or tape or cable tie it in place to keep it out of the way until you get home. The wheel will have a bit of a wobble on but chances are it’ll be sufficiently minor that you can ride home on it even if you have to let rim brakes off a bit..
4. Once back to base, get the old spoke out. You might have to remove a disc rotor or the rear cassette to achieve this. If the spoke broke at the elbow you can undo the spoke nipple and leave it in the rim. If it broke at the threads there’ll be a spoke nipple with a bit of spoke stuck in it, so you’ll need to remove the tyre and rim tape and take it out. You might as well take the tyre off anyway, it’ll make it easier to true the wheel in a bit.
5. Take your new spoke and thread it through the hub. It’ll either be head out or head in. On normal spoking patterns the spokes alternate in and out around the hub, so make the new one fit the pattern.
6. Cross the new spoke over and under the other spokes (again, look at the rest of the wheel to match the patter) to reach the vacant spoke hole in the rim, and thread a spoke nipple on to the end. Lube the spoke threads with something first. We usually just use chain lube because it’s lying around in the shed.
7. Stick the wheel in a truing jig (or back in the bike and Blu-Tac an Allen key to the chainstay as a pointer) and tighten the new spoke so it’s the same tension as all the others (pluck them to see how tight they are). As it gets tighter the wheel should unwibble itself.
8. Once it’s close, stress relieve the wheel by donning some hefty gloves and squeezing pairs of adjacent spokes together hard. Take care – if there’re any other fatigued spokes ready to break, this step could make them go… Finally, finish truing the wheel (instructions here) and there you go – fully intact and straight…
There’s hundreds of top maintenance tips in the BM archive.