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Help, is that a carbon damage?

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Help, is that a carbon damage?

Old 03-16-23, 02:54 PM
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Help, is that a carbon damage?

I removed the fork from the bike, just to clear it, removing some debris/dust.
Until i noticed a weird feeling.

If you inspect the carbon fiber with a light you can see lines, so there is nothing weird....
At the same time a crack will looks different. Those lines seems came from factory due to the molding process etc.

Here the video:

what do you think?
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Old 03-16-23, 04:41 PM
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I wouldn't trust a fork presenting such visible and possible manufacturing defects
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Old 03-16-23, 05:10 PM
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Lots of movement in that video, makes it hard to give a virtual visual inspection. Solid frame images might be more helpful, or give it the ol' tap test.
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Old 03-17-23, 05:32 AM
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For piece of mind - get it checked by a professional.

That's an important part right there - can put you on the deck hard if it fails.

Since exploding CF has put me on the deck hard - I err on the side of caution all the time.
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Old 03-17-23, 08:41 AM
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here guys what bmc told me.
I hope this tread will be usefull for someone in the future, at least to feel secure with those strange carbon fiber patterns.

"Thanks for your passion and to reach out BMC.
The "waves" that you feel on the steerer tube are caused by the normal drying of the clear coating layer.
On the other parts of the frame which are normally visible it would be finely finished and polished, but on the inside the frame this process is skipped.
The imperfections on the clear coating inside the frames are not to be considered in anyways dangerous.

Best Regards
BMC-Switzerland team"
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Old 03-17-23, 09:56 AM
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I agree with what BMC said.

There is too much unsubstantiated fear mongering of carbon bikes to be found still for something that has been with us for 40 some years. Some try to point out particular incidents they've seen or had, but that is circumstantial and ignores all the failures that steel and aluminum frames and forks have had.

Not that you are wrong to have questioned something you are not certain of. Hopefully this thread won't make others fear carbon or serve the fearmongers.
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Old 03-17-23, 11:28 AM
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BMC mention and a video.. I do remember this one which got a lot of eyeballs a few years ago:

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Old 03-19-23, 12:48 PM
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Seņor Ti makes an excellent suggestion. Intact, composite structures tend to pass "the violin test". If you tap on them, they resonate, like a violin, or guitar. If they have a defect, they don't. I would also examine the suspect spot with a good magnifier (~10x) to reassure myself.
Having an experienced expert look at it might also be more informative than our group speculation.
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