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My wheelset has alloy nipples which have severely corroded. It needs rebuilt with brass nipples.

However, my LBS can't get the spokes out. The nipples are too disintegrated to turn, but not disintegrated enough to just crumble to dust and release the spokes.

The LBS says the only option is to cut and replace the spokes. This will be expensive (multiples of the cost of a simple rebuild using existing spokes).

My questions are:

  1. Any suggestions how to get the spokes out?
  2. Specifically, are there any chemical tricks to accelerate the corrosion and entirely dissolve what remains of the nipples (without damaging the rims or spokes).

The wheelset has carbon rims, steel spokes, high-end straight-pull hubs, and alloy nipples.

  • You could try soaking with oxalic acid solution (sold in a paint store as "wood brightener" or "wood bleach"). Try this before you attempt using any sort of penetrating oil, as the oil will interfere with the ox acid. (No guarantees, of course.) – Daniel R Hicks Oct 26 '19 at 12:03
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    Are they very fancy spokes (e.g. bladed or elliptical)? Good double butted spokes are under £1 each (approx $1/€1) from my local stockist – Chris H Oct 26 '19 at 12:45
  • @ChrisH The replacements would be DT Swiss Competition spokes, straight pull and custom-cut to length. LBS says this would be a special order. – Jim Oct 26 '19 at 13:41
  • @DanielRHicks Sanity check: the oxalic acid shouldn't affect the steel spoke or the resin of the carbon rim? – Jim Oct 26 '19 at 13:41
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    DT Swiss Competition or similar from Sapim/Wheelsmith/etc shouldn't really be special order for a decent shop. – ojs Oct 26 '19 at 13:51
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In many other cases I'd apply heat (to the spoke) but I'd be wary of doing that here, because you could end up tempering part of the spoke, while it's still under stress. If you're unlucky that would lead to weakening. Also you don't want to get that much heat too near the carbon rims.

If you can get a few spokes right off, you may be able to slacken the wheel enough to flex the others and crack the bond (pliers on the nipples) or even to push the last few clear of the rim for more grip. This also means you can try different methods on different sections.

You haven't said how much nipple is accessible, but with enough access you could file or dremel a slot (nearly) parallel to the spoke without going right through, then put a screwdriver in the slot and twist to split it. You'd need to split it over a decent amount of thread though. In my touring rims that would be possible. I suspect your rims are rather different, and they'd only need to be a little aero to deny you access to any thread.

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    Although the spokes may be expensive they aren't probably that numerous so the expense will still be reasonable. And having been tensioned and submitted to stress then de-tensioned and re-tensioned could cause structural damage especially in the heads and at the neck of the threads. – Carel Oct 26 '19 at 12:51

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