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I repainted my bike and recently rebuilt the rear wheel. But the front wheel has some ugly rust on the spoke nipples while the rest, protected by the paint, looks fine.

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    Does your rim have paint on it? Is it steel ?
    – Criggie
    Commented Mar 20, 2023 at 21:22
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    @Criggie It's a stock wheel with a new coaster brake. I accidentally ruined the original. Commented Mar 21, 2023 at 22:50

3 Answers 3

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No, you are not supposed to paint spoke nipples.

Painting them could create a very hard to break joint between the nipple and its spoke, making eventual spoke tension adjustments hard to do. Paint can also get in the way of the spoke nipple tool.

If you have rusted spoke nipples, it is possible to replace them. They are very cheap to buy. Beware that if a nipple is rusted inside, it may be jammed on the spoke and there is a risk of breaking the spoke when trying to unscrew it. A bit of corrosion inhibitor spray can help break the rust joint. Take note of how far the spoke goes into the old nipple so you can screw the new one at the same level and keep a similar spoke tension. This way, the wheel would not go out of true. It is easier to change one nipple at a time and check for trueness before changing the next one than changing them all at the same time.

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    If you really wanted painted nipples, the thing to do would be take them off, remove the rust, refit them generously greased and paint carefully to avoid getting paint inside. Of course once you're dismantling the wheel you may as well fit new nipples. Also paint will chip the first time you true the wheel, so your rebuild would have to be spot on before painting
    – Chris H
    Commented Mar 21, 2023 at 9:05
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Painting over rust is a cosmetic coverup at best.

You can remove rust mechanically and then protect, but paint will almost certainly get in the threads which will cause frustration later.

There are also rust conversion products that transform brown iron oxide into black iron oxide, which is much more stable.

Personally I'd either ignore the problem for minor surface rust, or if I cared about the wheel I'd redo all the nipples with brass, OR anodised brass. I would never use aluminium because they do not last.

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    Painting rusty <insert any critical part here> to hide the rust is not only futile (the rust will continue to grow under the paint until the paint flakes off), but is downright dangerous, as you're likely to forget about it until the part is rusted enough to fail at just the wrong moment. At which point you'll definitely remember & regret the decision.
    – FreeMan
    Commented Mar 21, 2023 at 17:26
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    Presumably OP would paint over new nipples, to prevent the problem from occuring again in the future, not paint over the existing rusty nipples.
    – BrtH
    Commented Mar 21, 2023 at 19:30
  • @BrtH The paint would not last through one turn of a spoke tool, so painting would have to be done after assembly and truing. Also, brass doesn't rust. If OP had steel nipples then that would be exceptionally unusual. More likely the steel rim or spoke rusted.
    – Criggie
    Commented Mar 22, 2023 at 2:52
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    I was not aware that brass could be anodized. I don’t think that either the component metals can be usefully anodized. Nickel or similar coatings do exist, and Sapim reports using them for their brass nipples.
    – Weiwen Ng
    Commented Mar 22, 2023 at 11:28
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    I've come across steel nipples on a BSO (the spokes were galvanised), but everything else I've worked on has had plated brass nipples, presumably nickel
    – Chris H
    Commented Mar 22, 2023 at 21:50
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Rusting nipples are bad because chances are the threads are rusting, too. This keeps them from turning which will be necessary from time to time when the wheel gets out of true do to mechanical stress, or the spokes lengthen and you want to overall tighten them. Painting them, as the others have pointed out, is a Very Bad Idea. Greasing them is a god idea though to prevent moisture from entering the thread where it will do harm. Preferably you'd put grease on the nipple inside when you replace a spoke. It'll make your life easier when you try to adjust it a year or so later. If you need to adjust the spokes on an old wheel like yours it's a good idea to put some WD40 on the gaps where the spokes enter the nipple and wait half an hour before trying to turn them.

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  • At some point, will the rust cause the spoke threads to fail? Commented Mar 22, 2023 at 12:06
  • @EthanMiller Fail in the sense that they are fused, not that they will pull out, within the lifetime of us or the bike. Commented Mar 22, 2023 at 12:13
  • Until use, until you try to force an adjustment and something breaks. I've snapped M6 bolts that had rusted solid into aluminium; the fine thread on spokes will be more vulnerable than that
    – Chris H
    Commented Mar 22, 2023 at 21:53
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    @ChrisH Yes of course. "Fused" implied "inseparable short of destruction". Commented Mar 22, 2023 at 22:05

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