2

Is it common to see spoke nipples with heads rusted only on the side toward the hub, but not on the spoke body?

I'm working through all the spokes on my front wheel, inspecting and spoke prepping all the nipples and replacing some. The above rust pattern is what I'm seeing, on almost all the nipples.

If it matters, the spokes are (I think - magnetic) painted steel, the nipples are also slightly magnetic, and the rim is double-wall aluminum.

rusty spoke nipple

4
  • 3
    I suspect that isn't rust but rather simply decades of crud transferred from rim strips and tubes. – Daniel R Hicks Mar 16 '17 at 11:41
  • I'll keep an open mind about that until I can sand/Dremel one of the replaced ones down and see what's under there. On one hand, some look slightly deformed and enlarged the way rusty things can. On the other hand, the rust color of some is the same as the soil color around here and that could just be crud like you said. – compton Mar 16 '17 at 13:22
  • 1
    If it was rust, and both the nipples and spokes were steel, one would almost certainly find the nipples frozen in place on the spokes by rust. – Daniel R Hicks Mar 16 '17 at 17:22
  • I tried soaking for a couple days in mineral spirits then buffing with a cloth, with no change FWIW. – compton Mar 26 '17 at 13:56
6

That's an unusual rust pattern but not impossible. Your wheel has a cloth rim strip? Those hold moisture from rain and road dampness.

There's a chance your rim is not particularly waterproof, so moisture enters through the bead, possibly the spoke holes around the nipples, and maybe even through the tyre carcass. Plus there's sweating/condensation when warm and cool things meet.

Plus black tyres are great at warming up due to sunlight. So warm and wet, plus possible salt can corrode even stainless steel.

Spoke nipples are normally brass which doesn't corrode, but the nickel/chrome coating on the outside makes them look different. Sometimes race bikes have aluminium nipples but these are fragile and oversized and expensive.

You might have plain old chromed steel nipples too, if the wheel is old enough.

Grab some sandpaper and see how deep the rust is - it looks like purely surface rust in your photo.

Fresh nylon rim tape sounds like a good idea, and remove the fabric or paper tape. You don't have to replace the nipples, but they're cheap.

1
  • 1
    Warm, wet, and (paradoxically) reduced access to oxygen is what rusts stainless steel. A wet rim strip would be ideal - the damp cloth would stop too much O2 getting to the nipple, and then the SS can slowly continue to rust. – Martin Bonner supports Monica Mar 16 '17 at 16:38

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

Not the answer you're looking for? Browse other questions tagged or ask your own question.