Spoke replacement (which spokes to buy?)

[esuhl]

A few of my spokes have been damaged when the chain came off the cassette due to improperly adjusted gears. I've only noticed when I removed the cassette -- they must have been like this for ages!

So I thought I'd replace them carefully, one-by-one, threading them through the other spokes exactly as before. And I already have a spoke key and tension gauge. But...

What kind of spokes do I need? (They're for a mountain bike with 26" wheels.) Are there different ways spokes attach to the hub, different diameters, different metals used, etc...

Presumably, for the structural integrity of the wheel, I should replace the spokes with ones of identical specification (and, aesthetically, I'd like them to be black to match the others). Should I replace the nipples too...?

Can anyone explain what specifications I need to look out for, or any brands to go for or avoid...? Any tips at all would be gratefully received!

Cheers

[alexnharvey]

Take one out and measure it or take it to a shop. If you have a spoke key you can determine the nipple size. You need to know length, thickness and nipple size.

You'll need to know the length accurate to a millimetre. Rear drive side spokes are normally plain guage or possibly single butted. Probably 2mm or 14 gauge.

[pwa]

Take one to a good cycle shop. Might as well buy the nipples too, as it won't cost much. If you can get a good match.

[alexnharvey]

You'll also need to remove the cassette to replace the drive side spokes. If you know the nipple size and length it should be enough information to order some spokes. Get stainless ones, DT Swiss and Sapim are the most highly regarded. If you're not confident about the measurements then go to a shop.

[Brucey]

A few of my spokes have been damaged when the chain came off the cassette due to improperly adjusted gears. I've only noticed when I removed the cassette -- they must have been like this for ages!....

such damage is fairly commonplace. Actual spoke breakages arising from it are comparatively rare, hence you didn't notice 'the terrible damage' until you looked carefully. IMHO the biggest risk arising from leaving the spokes as they are is that you cut your fingers on the burrs when doing maintenance work, and yes, you might perhaps break some of the damaged spokes eventually.

In my spares stash I have lots of spokes of various different types, but even so I don't always have matching spokes and have to visit the LBS. If the damage is not too great and the consequences of failure not too bad (eg local use only, wheel is likely not to go too far out of true etc) then I will (at least as a temporary repair) straighten the spokes, dress the worst damage with a Swiss file, paint the damaged area if they are black-finished and true/stress-relieve the wheel. Often the spokes have to come out of the wheel (one at a time is best BTW) to be straightened. Often a 'temporary repair' turns out to be permanent.

BTW the possible fatigue damage arising in service is greatly reduced by the spokes being straightened. Also if there are any scratches left after dressing, it isn't a bad idea to improve the residual stresses in the spoke; an easy way of achieving this is to work that part of the spoke a little with a hammer, against a flat surface. Stress relieving the wheel is a necessary final step.

NB it looks terrible if you have to remove much material with a file and/or leave any scratches remaining. But

a) scratches need to be very bad before they represent as much of a stress concentration as other features already on the spoke (eg the screw thread for the nipple) and
b) chances are that a DB spoke is already in use or would be fit for this service. A 14/16/14 gauge spoke is only about half the cross sectional area in the 16G part vs the 14G part (once you allow for the nipple threads). I'm not saying that you can merrily file half a 14G spoke away, but you can probably remove more material than you think, with less risk than you expect.

cheers