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Carbon Seatstay Crack

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Carbon Seatstay Crack

Old 10-02-19, 07:12 PM
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Carbon Seatstay Crack

After my ride today, I noticed a small crack in the carbon monostay of my Bianchi S9. I'm not sure if this is a manufacturing defect or a failure. Anyone seen anything like this? The stays are Reynolds, and the crack is about a quarter inch long, right at the top of the monostay.
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Old 10-02-19, 07:35 PM
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Looks more like a join between the smooth part of the CF tube and the 'dimpled' part of the CF.
Doubt a coin tap would help. Probably needs bike shop eval if the you are first owner and a
warranty is applicable, but you might lose use of bike for awhile if it is. Based on the pix,
I think it is nothing to be concerned about.
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Old 10-02-19, 07:56 PM
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Was this bike bought by you through a shop? If so the I agree with having the shop (or other Bianchi dealer) examine the bike and have notes in their service system made. Even if they suggest it's no big deal you want the company to be on notice now. Do remember that most shops have no one with real carbon construction experience, sure there're lots of opinions but very few with true abilities. That isn't the point though. Getting documention now for any future ssue is.

I would also witness mark (love that term) the "crack's: ends best possible to further track development. Is there access to the mono stay's interion (vents, openings to other tubes)? If so then a penetrant could be introduced to the interion to see if it bleeds out via the "crack", Note that as a layered construct any crack might not be fully through the tube wall. Andy
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Old 10-02-19, 08:17 PM
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If you'll carefully notice, it looks like there is a section of more textured carbon that runs up to a smoother section. Both seem to intersect at that junction point that appears to be a "crack". I think it's just a point of where the carbon layers met, not really a crack. But if it were me, I'd still have it looked at by someone competent in making such evaluations.

My guess is it shouldn't be so scary. But hey, I've been wrong before. I am married, after all.
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Old 10-02-19, 08:54 PM
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What year is the frame?

Last edited by hefeweizen; 10-03-19 at 06:50 AM.
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Old 10-02-19, 09:17 PM
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Riding season gets shorter every year.
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Old 10-03-19, 03:10 AM
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What is the opposite side like?
Pull it back and forth and see doesn't open up.
Go from there.
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Old 10-03-19, 10:17 AM
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Thanks for the feedback. Frame dates from 2005, and I did not buy it new. I did notice the difference in carbon texture right at the hairline. I will monitor the situation and see if it gets worse.
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Old 10-03-19, 10:52 AM
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That is an odd place for a crack to develop, plus it does not follow the lug line, but is straight across the tube. As you said, monitor and inspect to see if it travels.
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