Mountain Biking - Is this concerning damage on a CF MTB frame?

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redfooj
09-24-12, 11:23 AM
2010 Trek Elite CF Frame
Bottom of BB got nicked on a rock... owner filled gouge with JB Weld and then taped over

http://i.imgur.com/bwu6V.jpg?1

doesnt look deep but is in a stress-sensitive area. do you think it will hold up?

mtnbiker66
09-24-12, 11:36 AM
You can fix anything with JB Weld and some tape....... Throw in a mountain dew can and you can save the world. I had a friend that rode a carbon bike with a lot bigger gouge than that with no issues........but I have no clue about carbon bikes so someone else will need to answer this for ya.
dminor
09-24-12, 12:00 PM
With a JB Weld job, if you don't wave a black light over it for the first 5 minutes of catalytic reaction, the aluminum particles will not properly grain-align - - something that is crucial to patching CF. The only way to determine now if there was proper grain-alignment is with a Zyglo scan.

mtnbiker66
09-24-12, 12:17 PM
With a JB Weld job, if you don't wave a black light over it for the first 5 minutes of catalytic reaction, the aluminum particles will not properly grain-align - - something that is crucial to patching CF. The only way to determine now if there was proper grain-alignment is with a Zyglo scan.

....and I guess you could do that for a fee?
Grimlock
09-24-12, 12:29 PM
It depends on what type of rock he hit in the first place. The JB Weld can over-catalyze if it was a sedimentary or igneous rock. If that was the case, I'd strongly suggest media-blasting (with ball bearings) the bottom bracket to remove the JBW. Once you've ball-burnished the BB with BBs, be careful to rub a little mineral oil from your XT levers on the affected area. You want to break in the break in the clearcoat with brake fluid, lest it break while you're braking. If it breaks, you'd be broke.

Tl;dr It's fine.