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Discussion Starter · #1 ·
One of the guys I work with is an avid rider. He told me he broke a spoke and brought it in to show me. The aluminum nipple broke in half right near where the spoke threads ended. I thought this was an unusual failure since the main stress would seem to be in the direction of the spoke. This person is a light rider and nowhere near the weight limit. Anyone else seen a failure like this?
 

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changingleaf
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It is fairly normal for a spoke nipple to brake from fatigue if the spoke is not threaded all the way into the head of the nipple. If the spoke is not threaded into the head of the nipple it pust tension on the nipple and eventually can break where the end of the spoke has been threaded to.
 

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Discussion Starter · #4 ·
So where did the spoke threads end? (relative to the top of the nipple)
I couldn't tell since he did not bring in the part that snapped off. I can only say the nipple part that was still on the spoke had not yet "mushroomed" out
 

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A wheelist
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I couldn't tell since he did not bring in the part that snapped off. I can only say the nipple part that was still on the spoke had not yet "mushroomed" out
As Leaf said, the spoke MUST be up into the head of the nipple or the thin vulnerable nipple neck takes all the spoke tension. So the devil is in the details - we don't really know where the end of the spoke was relative to the neck, the slot, the nipple top.
 

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In other words, this is a hazard when using aluminum nipples and spokes that are too short. It's a screwup in spoke selection by the wheel builder.
 

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A wheelist
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In other words, this is a hazard when using aluminum nipples and spokes that are too short. It's a screwup in spoke selection by the wheel builder.
Brass nipples just allow the careless (incompetent? deceitful?) wheelbuilder to hide the issue a bit longer. Even brass nipple necks are not designed to take spoke tension.
 
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