Cracking nipples- Mtbr.com
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  1. #1
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    Cracking nipples

    Cracking nipples-_dsc4628.jpg

    The nipple broke, but the spoke was fine--in fact I reused the spoke when I replaced the nipple.

    Three months ago, I built up this rim, my first carbon rim, an Ibis 742, with these 14mm high strength aluminum nipples, and these stainless washers(recommended by Ibis), with DT Swiss Comp spokes (2.0/1.8), and an Onyx rear hub.

    I used one layer of Kapton tape, which was in good shape when I removed the tire to fix the spoke, and there was no sealant leaking onto the spokes. This is the second drive side nipple that cracked in the last 3 weeks.

    After I built the wheel, I noticed that some of the drive side nipples weren't aligning well with the spoke line, which concerned me. Do I need to use nipples with a more rounded head so that they can align better with the spoke line?

  2. #2
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    3 months is pretty early for any nipple failures from galvanic corrosion, but it still should be checked, any powdery white substance/pitting and signs of corrosion? Walk us through your build process. How did you verify tension with a tire installed? Some rims have angled holes for the spokes and if you go "opposite" it'll put the spokes at an extreme angle.
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  3. #3
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    Cracking nipples

    Are your spokes threaded all the way through the nipple? If not, they can break. A straight spoke line between the rim and the hub is also necessary. Bending will eventually crack the nipple. Maybe you should use brass nipples.

  4. #4
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    Quote Originally Posted by MikeDee View Post
    Are your spokes threaded all the way through the nipple? If not, they can break. A straight spoke line between the rim and the hub is also necessary. Bending will eventually crack the nipple. Maybe you should use brass nipples.
    That's key, the spoke should be flush with or barely protrude from the nipple IME on the backside. If it doesn't, it tends to break the nipple at the flange.
    "It's only when you stand over it, you know, when you physically stand over the bike, that then you say 'hey, I don't have much stand over height', you know"-T. Ellsworth

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  5. #5
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    Looks like you didn't figure the washer into spoke length. Redo with brass.

  6. #6
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    I've only built with brass nipple for this very reason.

  7. #7
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    Agree with others, spokes look short and you should switch to brass nipples.

    The other thing I would check is that you didn't lace the wheel wrong. Usually higher quality rims like your Ibis rims have the spoke holes drilled on an angle so the spoke is aligned strait with the flange. It can only be laced one way properly.

    If you laced it wrong they could all be pointing out at the wrong angle and adding to your problem.
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  8. #8
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    Thanks for the responses.
    Looks like you didn't figure the washer into spoke length.
    I measured the ERD with washers and nipples on my measuring spokes.

    any powdery white substance/pitting and signs of corrosion?
    Nope. I'll post a picture of the both pieces of the cracked nipple when I get a chance.

    Walk us through your build process.
    I follow Roger Musson's ebook except I put Wheelsmith Spoke Prep on the threads of the spokes. Before lacing, I determined the drilling of the spoke holes, so that I got the first spoke to the left of the valve hole orientated correctly, then the rest of the lacing builds off that. I used a homemade nipple driver to screw down the nipples to the same thread position on each spoke. Then I went around the wheel a couple of times to add some tension. Then I used a big, long screwdriver to bend the outside spokes so that they nestled against the hub flange. Then I dd some radial and lateral truing, which was very easy with this carbon rim, while bringing the spokes up to 120 kgf, which I measured with my Park tensionometer.

    How did you verify tension with a tire installed?
    My Onyx rear hub has a max 120 kgf, so I built to that tension with no tire installed. By which I mean, the tightest spokes were 120 kgf.

    Some rims have angled holes for the spokes and if you go "opposite" it'll put the spokes at an extreme angle.
    Yes, I checked that very carefully. I determined that the first spoke to the left of the valve hole (with the valve hole at 12:00) should go to the drive side of the hub. Roger Musson calls that a Type 1 rim.

    Are your spokes threaded all the way through the nipple?
    What do you consider all the way through the nipple?

    Roger Musson's spoke calculator targets the end of the spoke to be flush with the bottom of the slot on the nipple, and looking at the break I estimate that that's where my spoke ends ended up.

    I'm wondering if it's possible if the flange of the nipple did not allow the nipple to rotate far enough to be in line with the spoke.
    Last edited by happyriding; 1 Week Ago at 01:49 PM.

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