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Thread: Tubeless sealant and corrosion

  1. #1
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    Default Tubeless sealant and corrosion

    I just rebuilt a customer's wheel that was on a tubeless rim and spokes laced with alloy nipples. More than half of the nipples were so corroded that there was material missing from the part inside the rim--six nipples cracked inside the rim.
    All nipples show signs of corrosion--could this be from tubeless sealant and has anyone else seen this? FWIW, I rebuilt the wheel with brass nipples.
     

  2. #2
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    Default Re: Tubeless sealant and corrosion

    yes, this was a thing, for sure. at one point shimano recommended against using sealant in their tubless wheels. i think the sealant manufacturers have caught up to this now though and have modified their solutions to be less corrosive, but not positive about that...

    Technical FAQ: Corroded rims and hot heads | VeloNews.com

  3. #3
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    Default Re: Tubeless sealant and corrosion

    I don't build wheels with non-anodized alluminium nipples, they are too easily subject to corrosion even without using a tubeless setup. The sealant may only accelerate a problem that is already there.
    Andrea "Gattonero" Cattolico, head mechanic @Condor Cycles London


    "Caron, non ti crucciare:
    vuolsi così colà dove si puote
    ciò che si vuole, e più non dimandare"

  4. #4
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    Default Re: Tubeless sealant and corrosion

    Quote Originally Posted by Vancouverdave View Post
    ...tubeless rim...All nipples show signs of corrosion--could this be from tubeless sealant...
    No...
     

  5. #5
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    Default Re: Tubeless sealant and corrosion

    What wheel?
    Dustin Gaddis
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  6. #6
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    Default Re: Tubeless sealant and corrosion

    The sealant shouldn't come in contact with the nipples imho. Non ano nipples are just a very bad idea.
    --
    T h o m a s

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    Default Re: Tubeless sealant and corrosion

    Front Roval carbon 29'er; black anodized nipples. Used Stan's sealant.
     

  8. #8
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    Default Re: Tubeless sealant and corrosion

    The more I build wheels (35 years and counting) the more I think that any non-brass nipples are a bad idea!
     

  9. #9
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    Default Re: Tubeless sealant and corrosion

    Quote Originally Posted by Vancouverdave View Post
    The more I build wheels (35 years and counting) the more I think that any non-brass nipples are a bad idea!
    I couldn't agree more.
     

  10. #10
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    Default Re: Tubeless sealant and corrosion

    Quote Originally Posted by Vancouverdave View Post
    Front Roval carbon 29'er; black anodized nipples. Used Stan's sealant.
    I figured. It's extremely common with those wheels, rebuilt a set of those rims to some Hope hubs today actually, and it's not my first pair. My theory::

    They're built with hex head nipples. The heads get scratched during the build process, exposing bare aluminum. Or, being that they're DT nipples, they are scratched when brand new, with exposed bare aluminum. Sealant gets past the rim tape (the tire bed is pretty lousy and uneven on those rims, and IMO most shops don't do a great job taping rims), and then corrosion sets up and takes place.

    The ones I rebuilt today, there was so much moisture and sealant and general funk inside the rear rim I had to take it outside and rinse it out (as best as I could) and let it dry before rebuilding. Lots of little white aluminum oxide pieces and dust came out too. I used brass to be safe.

    I build alloy nips and carbon rims all the time and have never had an issue, but those Rovals are notorious for eating alloy nipples.
    Dustin Gaddis
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    Default Re: Tubeless sealant and corrosion

    I rebuilt with a new rim, but your description of the crap inside the old rim rings true.
     

  12. #12
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    Default Re: Tubeless sealant and corrosion

    Is there direct carbon to aluminum contact of the nipples at the nipple hole? Aluminum in direct contact with carbon can create galvanic corrosion. I know I have heard carbon frame builders talk about the dangers of using unprotected aluminum BBs in a carbon frame. Perhaps this could be causing, or maybe exacerbating the corrosion issue on these wheels.
    - Brad Comis

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    Default Re: Tubeless sealant and corrosion

    Quote Originally Posted by WheelNut View Post
    Is there direct carbon to aluminum contact of the nipples at the nipple hole? Aluminum in direct contact with carbon can create galvanic corrosion. I know I have heard carbon frame builders talk about the dangers of using unprotected aluminum BBs in a carbon frame. Perhaps this could be causing, or maybe exacerbating the corrosion issue on these wheels.
    Maybe a bit. The carbon is inside epoxy, and the nipples are anodized, but when you drill the carbon there is some exposed carbon, and tightening the nipples could strip a bit of anodizing.

    I think the issue is more bare aluminum (scratched nipples) mixing with the ammonia in sealant, and staying in a nicely damp environment.

    ENVE's early wheels used non-anodized alloy nipples, and those corroded into nothingness even on some wheels with no sealant, so galvanic corrosion could certainly been an issue in those cases (especially if the wheels were used in salty areas). Now they use brass nips.
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  14. #14
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    Default Re: Tubeless sealant and corrosion

    Quote Originally Posted by WheelNut View Post
    Is there direct carbon to aluminum contact of the nipples at the nipple hole? Aluminum in direct contact with carbon can create galvanic corrosion. I know I have heard carbon frame builders talk about the dangers of using unprotected aluminum BBs in a carbon frame. Perhaps this could be causing, or maybe exacerbating the corrosion issue on these wheels.
    Whatever is the material, some Lithium grease on the outside of the nipples is most often a good idea. Not only will prevent corrosion starting between the two parts in contact, it will also make for an easier build of the wheel
    Andrea "Gattonero" Cattolico, head mechanic @Condor Cycles London


    "Caron, non ti crucciare:
    vuolsi così colà dove si puote
    ciò che si vuole, e più non dimandare"

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