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crack in clear coat for carbon fiber fork

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crack in clear coat for carbon fiber fork

Old 07-30-07, 02:53 PM
  #1  
rene_sc
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crack in clear coat for carbon fiber fork

So I just bought a Bianchi Giro 2006 the other day. I noticed when I rode it home that the rear carbon-fiber fork had a 19mm crack running up the fork. I took it to my LBS, and they inspected it and said that it was just the clear-coat separating from the carbon. He put some more clear coat on, and it has kept the crack from being open to the air. He said the carbon-fiber underneath was fine.

1)Does a crack in the clear-coat compromise the integrity of the fork?
2)Will the crack in the clear-coat keep growing?
3)It doesn't look like the rear fork can be removed. Is it permanently attached to the rest of the frame?
4)This is a brand-new bike...with a problem like this, should I send it in to Bianchi for a replacement frame?

Thanks for your help.
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Old 07-30-07, 02:57 PM
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Cervelo said they were just clearcoat cracks too! Then they recalled frames. I'd say watch it, and if it re-develops, make them warranty the frameset.
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Old 07-30-07, 02:57 PM
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When you say "rear fork", what are you referring to?
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Old 07-30-07, 02:59 PM
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Sounds like trouble to me.
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Old 07-30-07, 03:02 PM
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The rear fork coming down from the top tube to the wheel hub. The Giro doesn't have a full carbon fiber triangle.
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Old 07-30-07, 03:05 PM
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The seat stays?
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Old 07-30-07, 03:08 PM
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Sounds like the seat stays to me. Was it a CRACK, or a SCRATCH? A scratch probably not a big deal, a crack, well that's a different story.
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Old 07-30-07, 03:10 PM
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The top tube of the rear triangle. If that is the seat stays, then I apologize for my stupidity.
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Old 07-30-07, 03:11 PM
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Post a picture...
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Old 07-30-07, 03:13 PM
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It is a crack... 19mm long, and running up the top ridge of the rear triangle. The guy at the LBS could see right down to the carbon fiber...I guess, because he said that the carbon was ok. Also, the crack is now sealed, but I can depress the clear-coat area right around the crack (less than 1.5mm, but still observable.) It seems like there is a little space between the clear coat and the carbon.
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Old 07-30-07, 03:13 PM
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I'll post a pic, but it might take a couple minutes.
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Old 07-30-07, 03:14 PM
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Ah, I looked it up and see the confusion.

https://www.bianchiusa.com/06_giro.html
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Old 07-30-07, 03:14 PM
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If you can physically deform the carbon, it's not a clearcoat problem...

Go to another shop. Where are you?
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Old 07-30-07, 03:19 PM
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Clear coat is like the wax buildup on a car. it doesn't crack, it wears off, often in a round or oval pattern. If you see an actual crack run for the hills.
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Old 07-30-07, 03:36 PM
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I can't get a good pic of the crack...the flash just gets reflected off of the clear-coat, and w/o the flash, the tube looks perfectly fine. And yes...it is the seat stays...I guess I learned something new today. But it's a straight-line crack running up the inner-ridge of the seat stay.
The LBS I went to is in Santa Cruz CA, on Mission and Trescony. I'm not sure if I'm allowed to name names, so If you know the area, there's really only one bike shop there w/ Bianchis.
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Old 07-30-07, 04:02 PM
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I would ask the LBS to warranty the frame immediately or return the bike.
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Old 07-30-07, 04:04 PM
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Originally Posted by rene_sc View Post
I'm not sure if I'm allowed to name names
No one is stopping you.
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Old 07-30-07, 04:29 PM
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Do you know any X-ray technicians at a nearby hospital that could sneak your frame onto the table?

Or, find an industrial radiographic testing lab nearby and have them radiograph the area. A radiographic image will tell you if you have a crack or not.

There's another method of "non-destructive testing" called liquid penetrant testing. An industrial non-destructive testing lab (which is generally where you will find industrial radiography) will have access to fluorescent water washable liquid penetrant. But, you would have to remove the clear coat fix that the LBS performed. The penetrant basically penetrates any cracks/defects. You wash off the residual penetrant and what remains in a crack or void will be visible using a black-light. They make an oil based penetrant that is visible...it has a red dye and you use a white powder....but it would require some pretty stout industrial cleaners to remove it...which I don't think are too friendly to paint finishes.
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Old 07-30-07, 05:17 PM
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Actually, I do know an X-ray technician. I'll use him. Thanks for the tip.
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Old 07-30-07, 05:28 PM
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Originally Posted by rene_sc View Post
Actually, I do know an X-ray technician. I'll use him. Thanks for the tip.
Being used to looking at pictures of humans, a chunk of carbon might prove a challenge to your buddy... why risk life and limb on his analysis, when it really shouldn't be your problem?

19mm is a significant flaw in an expensive bike- even if it is just in the clearcoat. The fact that carbon is notoriously sketchy in this area makes the situation even more unacceptable with a new bike. Go to the store and don't leave until they agree to warranty the frame.
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Old 07-30-07, 05:29 PM
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If there is any depth at all, it is more likely a crack in the gel coat, not the clear coat. A clear coat is no thicker than a coat of paint and is only intended to protect a painted or gel coated surface and add luster and shine. The gel coat is the layer outside the carbon fiber and is usually white, black, grey or clear (clear when a builder wants to show the carbon fiber). By your description, it is the gel coat that is cracked and yes, it certainly does affect the structural integrity of the frame. It should be warrantied immediately. I would not ride the bike as is.
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Old 07-30-07, 05:32 PM
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Return the bike immediately, and don't take any excuses. Why take the chance? It is a new bike and it should be right straight out of the shop.
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Old 07-30-07, 05:35 PM
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This here issue reminds me of that commercial for whatever when two inspectors are walking along a dam and plug a hole with a piece of gum, only for it to get worse. This sounds like the exact same situation, any form of crack in any carbon fiber parts are worth warrantying. When Carbon Fiber breaks, it rarely ever is clean, sharp bits can be quite hazardous. Warranty the frame, if the shop wont do it, return the bike and leave. If they won't take the bike, call your x-ray technician friend and ask for his lawyer.
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Old 07-30-07, 08:58 PM
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Originally Posted by rene_sc View Post
Actually, I do know an X-ray technician. I'll use him. Thanks for the tip.
If he is an X-ray tech at a medical facility, he will have access to use an X-ray tube which will give you a very good image of the seat stay. If it's cracked, it will be a no-brainer on film...especially using an X-ray tube.

I have access to an industrial radiography crew which uses a radioactive isotope for their radiation source. Not near the quality of a tube, but with the right film, can still put out decent image. For kicks and grins, I had them radiograph my frame...here's a couple pix. We weren't looking for cracks as much as we were for uniform carbon thickness throughout the frame. Those Spaniards sure know what they're doing when it comes to hand laying carbon fiber!
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Old 07-30-07, 09:06 PM
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Blue-Shamu, thanks for your posts and graphics regarding carbon cracks. I'm going to bookmark this page for future reference it case it's ever needed. You've provided excellent ideas and feedback.
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