Hi All,

Apparently this is quite a common malfunction, and I've had a good old look around on the interwebs but can't find a sure-fire way of going about fixing it. The rivnut on the downtube on my posh bike has ripped out (through me not greasing the bottle cage bolts....), leaving a largish hole. It's one of those things I've put off trying to resolve for over a year, but I really do need to get it sorted soon!



The hole is larger than a rivnut, so I need to build up a surface for the nut to grip. Ideas I've considered include

Patching the hole from beneath by somehow squeezing in a patch of cf, applying some resin, adding a couple more hole shaped layers of cf and filling until there is no hole to speak of. Then drilling and inserting a new rivnut

or

Inserting a pre-squashed rivnut and building up the sides of the hole with epoxy filler/resin. This seems more of a bodge and I'd worry about it not being a permanent repair.

or

Sending the frame off to a cf repairer who knows what they're doing?

Thanks!


PS Sorry for the large picture!

If the carbon around the hole isn't damaged or is easily repairable with a drop of resin then why not make a bigger insert?  Rivnuts are a bit harsh through a laminate so a screw anchor would be better however, I'd be tempted to turn up a bigger insert and just bond it in with something like bigbond.

As above, a bigger insert would be the best cosmetic and simplests structural solution.  Unless youve got access at one tube end, youll struggle doing an internal repair.  External repair is dead easy but will be clearly visible and for something as minor as that, would be a shame to ruin the look of the bike.

Warren Penalver
Easy Composites / Carbon Mods - Technical Support Assistant

That's great. I think I was worried about the resale value, but at the end of the day a larger insert isn't really going to spoil the looks as it will be hidden by a bottle cage. Measurements indicate I should get away with an M8 rivnut (with a squidge of filler).