SesameCrunch

Need some help from carbon fiber experts here. I have a new Fuji carbon bike with about 400 miles on it. Last week, I had new compact cranks put on. In the process, the front derailleur was lowered by 1cm or so. Today, I noticed that the seatstay where the FD was previously clamped is slightly indented, and there's a bubble where the FD used to be. It looks to me like the FD was bolted on too tightly at the factory. I can't see a crack all the way through the stay, I think it's just an indentation.

What do you guys think? Is this a non-issue, or should I go argue for a warranty replacement? Do you have any suggestions for how I can better determine if there is a crack?

Thanks in advance for any constructive suggestions.

christo87

Carbon fibre can't dent, it would have cracked completely. It is probably designed that way.

gpelpel

Carbon won't dent. It cracks or may be chipped. A bang against a sharp object may chip a frame, it is usually still very safe. If your derailleur was too tight it would have cracked the frame.

Bob S.

The carbon is a composite laminate. A composite, depending upon the type (reinforcement & matrix/resin) and circumstances (load, temp., etc) can deform. Look carefully at the distrortion under good light & strong magnafication. Are any small cracks visible? Look mainly in the resin & the resin to carbon interface as the resin will usually fail before the carbon fibre. Become concerned if you are able to see cracks. Best to get a composite tech who is familiar with carbon to look @ it if you do see any of small or micro cracks. If no cracks & minor amount of deformation, you are probably ok.

On Edit. I missed the part about the bike being 'new' w/ about 400 miles. Under these circumstances, I would attempt to return the bike. Ie. The production time & assembly time may have been so short that the FD was installed & tightened while the resin was still 'green' in which case there will likely not be any micro cracking evident, just distorted laminate. Why make their problem yours? Certainly, it will devalue the bike & negitively affect the resale. Bob

DannoXYZ 

FDs clamp to seat-stays? Pictures?

bluecd

from my cannondle synapse carbon owners manual.

"Delamination

composites are made from layers of fabric. delamination means that the layers of fabric are no longer bonded together. delamination is serious. do not ride any bicycle or component that has any delamination.

delamination clues:

a cloudy or white area. this kind of area looks different from the ordinary undamaged areas. undamaged areas will look glassy, shiny, or "deep", as if one was looking into a clear liquid. delaminated areas will look opaque & cloudy.

bulging or deformed shape. if delamination occurs, the surface shape may change. the surface may have a bump, a bulge, soft spot, or not be smooth and fair.

a difference in sound when tapping the surface. if you gently tap the surface of an undamaged composite you will hear a consistent sound, usually a hard sharp sound. if you then tap a delaminated area, you will hear a different sound, usually duller, less sharp."

SesameCrunch

I think the description of delamination describes my situation. There is indeed a cloudy bubble. The shape has changed as I said. I tried the tapping technique, but I think I have to remove the FD clamp before I can tell if the sound is different.

Thank, bluecd. I think you nailed it. I will see what my owners manual says also. I'm going to take it back in and argue for a replacement. As BobS said, no sense in making this my problem.

Thanks for your help!!!

SirScott

A brand new bike with delam problems? Call me skeptical.

I'm in agreement with the others who say that it's built that way. Numerous framesets have indentations or other design features where the front derailleur typically mounts. When you throw on a compact crank, the derailleur will have to be mounted a little bit closer to the bottom bracket and therefore not sit in that nice indentation.

Bob S.

[QUOTE=SesameCrunch]I think the description of delamination describes my situation. There is indeed a cloudy bubble. The shape has changed as I said. I tried the tapping technique, but I think I have to remove the FD clamp before I can tell if the sound is different. /QUOTE]


'Cloudy Bubble' with bump. Dead give away. The 'cloud' is caused by the mirco fractures in the resin matrix.

Not enough information (ie. layup, cure, etc.) is available to us to determine if this a serious problem or not. That is for the mfg. to deterimine. Take it back. Put it on record. If they deny replacement, at least you have it on record in the event that you have a failure later. You may be pleasantly surprised and find that the mfg. is happy to replace it in is interested in the problem from a Q.C. standpoint. I have seen that happen many times.

Good luck with it. Bob

SesameCrunch

I can buy the indentation as being designed in, but it doesn't explain the cloudy bubble, which was not there previously...

Plus, BobS's explanation of the manufacturing process/defect makes sense to me. They clamped the FD on too soon and the resin formed around the clamp. When we moved the FD, the stresses changed, and the separation occured, forming the bubble.

Whatever the cause of the indentation, my concern is now more about the bubble, which might be indicative of delamination. I'm planning to take it into the shop and see what they say. I'll give you all an update.

Thanks again for your input.

SesameCrunch

Sorry, I meant seat tube...

SesameCrunch

So I just got back from the bike shop. The upshot is as follows:

- They agree it's a delamination and they will contact the mfg for a frame replacement.
- Some of you were right, there is an intentional indentation for positioning the FD,
- Cause of the delamination is probably due to the new FD position sitting along one of the ridges of the indentation, concentrating the stress (the bike shop did the work).

At any rate, the shop will contact the mfg and initiate the frame replacement process. I hope the process goes smoothly. It'll probably take a few weeks so I'll get a chance to get re-acquainted with my 2002 Lemond Zurich.

As a side note, I had recently been thinking of selling the Zurich (Reynolds 853 steel frame) since I wasn't using it much after getting the new Fuji. But this experience reminds me that steel is trusty, carbon is fickle and I have no intentions of selling it now .

bbp

delams can be resin sealed.

FastFreddy

Thanks for posting a good description of what to look for. I love my Trek CF road bike but I’ve always had the thought that there could be a delamination problem – it’s nice to know what to look for. I have no intention of giving up on carbon – it’s the best for comfort – but I ride a steel commuter bike for routine transportation.

I’m glad to hear that Fuji is going to make this right – they obviously should.

Michigan

I've got one of those indented FD rings in my CF project, so I'll have to remember to go easy on the clamping after reading your story. I hope you get a new frame, but if not, I agree with bbp in that it should be easily repairable.

EricDJ

Its funny that you mention indentations where the FD mounts. I was thumbing through my repair book I got and happened to pass the FD page. Where the FD goes there was indentions as in this picture. Look at the derailer inside too.

Bob S.

Congratulations. Sounds like a class A shop. +1 for the good guys and a strong recommendation for using the same shop for purchase & service.

Yes, delams can be fixed. Usually not too big of a deal for an expereinced tech or a very good hands on type. Bob

Rides4Beer

How the **** do you even find a 16 year old thread??