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I've been over-tightening presta valve cores for years and only realized it when one snapped in a customer's tube yesterday.

The tip-off was the tiny, clean break right at the base of the valve stem, which happened while I was just snugging it up with my fingers, not a tool.
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3 Comments
sarah_brown
That clean break pattern means the brass was already fatigued from previous over-tightening.
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ross.kelly
ross.kelly1mo ago
Actually looks more like a casting flaw.
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the_kai
the_kai21d agoMost Upvoted
Read something about brass fatigue cracking from vibration once.
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