[Bob Ross]

So the threaded insert behind one of the bottle cage mounting screw holes on my carbon Synapse seat tube got so corroded/fused to the screw that it snapped off inside the frame when I tried to remove the screw.

It's been suggested that all (sic) I need to do is get a new "rivnut" installed to make this cage mounting location usable again.

Anyone know if this is actually possible, and is it a (hopefully) simple operation on a carbon frame?

My concerns are twofold:
1) everything I know about "rivnuts" suggests it's the perfect option for a metal frame, but I just don't know anything about their applicability to carbon fiber frames
2) if a "rivnut" (or some other such threaded insert that gets installed through the front of the hole) is not the appropriate solution, I just can't quite fathom how someone would install something from the back on a frame that's already built...they'd either have to go through the bottom bracket or the top of the seat tube, and I just can't imagine how they could do that without the kind of flexible tools/lights/cameras that an arthroscopic surgeon uses!

Any elucidation would be appreciated. Thanks.

 

[AvantDale]

I'm in sorta the same boat as you. One of the inserts for the bottle cage ripped out.

I think my only option is to send the frame up to Calfee to get it fixed.

 

[Dan Gerous]

I think many bike shop can fix this. I'm not sure how they do it but they can probably bond the threads/nuts back in place or put new ones... A little bit of grease on the mounting bolts could be a good idea next time, and no need to tighten them too hard either.

 

[Bob Ross]

A little bit of grease on the mounting bolts could be a good idea next time

To be honest I was really surprised that the LBS that built the bike up (presumably) didn't do this...although it was also suggested to me that regreasing those threads every year should be a part of routine maintenance, so I'm not really pointing fingers

...well, maybe a little.

But yeah, any of the screws I've subsequently installed on my bike, or shoes, always get a liberal coating of Phil Woods Waterproof Grease. It was just a fluke that I'd never had reason to remove the rear bottle cage in four years.