Subject: Re: Look Carbon frame problem...don't panic! Posted by: Al on November 14, 2005 at 06:04:36: In Reply to: Look Carbon frame problem...need help! posted by Kevin on November 11, 2005 at 11:27:30:

Message: >I have a 2003 Look KG386 frame on which the front derailleur mount is loose. No amount of torque used on the bolts will prevent the derailleur from moving. Does anyone know the mechanism by which the bolts are held into a carbon fiber frame? How can they become loose? Can it be fixed? >Thanks in advance. FIRST. If the "braze-on" mount is "loose" you can always consider substituting a regular, clamp-on front derailleur (probably a 31.8 will fit) -- a large number of the LOOK frames do NOT have "braze-on" mounts. The threaded anchor/eyelet that was inserted into the carbon fiber (carbon fiber, itself, cannot be threaded according to some) has broken free. The anchor was either splined or knurled, and at this point, you have probably enlarged the receiving hole, slightly. You/someone will have to take the "braze-on" mount off the frame ... Since your "braze-on" is bolted on, you can apparently, simple loosen the "other" bolt(s?) and it will probably pull away from the seat tube. You have at least two options/choices with regard to anchoring your frame's "braze-on" front derailleur mount: * unthread the eyelet from the bolt, and use some JB WELD [an epoxy which I believe has some fibers embedded in it to add strength] to re-anchor it [follow the instructions on the package]; OR, * get a [blue] plastic anchor used for drywall (I think there may be different sizes!) -- this will provide a more secure mount than you would think, BUT I cannot guaranteed that it will be strong enough for the forces a derailleur will put on it; however, it should be good-to-go as soon as you expand the anchor with its screw -- if properly sized, it will certainly be more secure in your frame than in a drywall board. Personally, I would re-enforce the "bond" with a dab of latex caulk adhesive which will be squished into a thin layer when you bolt the "braze-on" back onto the frame. Either "repair" should cost you less than $5.00 for the supplies if you don't already have any of it on hand. In either case, I would wait 24+ hours before mounting & using the derailleur after re-securing the "braze-on" mount. Again, since your "braze-on" mount is bolted in place (consider yourself lucky -- on my carbon fiber frame the "braze-on" is glued-and-riveted), you could temporarily remove the it and simply use a clamp-mount front derailleur. Briefly, when I was looking for an interim solution when my braze-on needed to be re-aligned I considered mounting a low-mount MTB front derailleur beneath the braze-on mount ... THAT substitution was NOT viable because the parallelogram is essentially BEHIND the seat tube where the tire wants to be!