Does failure of the weld around both bottom cage bosses count as a frame failure? I didn't let the bolts corrode then use mighty force to shear the whole thing, I came to fit a bottle cage one day and the bolts and boss just rotated, but I wouldn't expect anyone to believe it (it is true!). I'm sure the frame will be fine but do you think there'd be any mileage in contacting the LBS/manufacturer.

Is it just that the rivnuts need tightening?

Ha! I had a quick look this morning, no welds evident! Bit of an assumption that. Rivnuts you say, how do they work then? How do I go about tightening them? The bolts are in but there isn't a cage on it. Molegrip job?

11 years of mountain biking and I can still make a complete tit of myself in public, classic! 😀 😳

If the bolts are in, it might be tricky. You need to get a grip on the outside of the rivnut while you undo the bolt, not easy. Have a google for rivnuts to find a diagram of how they work. Basically, they're "pulled" up agsint the back of the tube. It is possible to tighten them up with a spacer and a bolt but to do this, remember to find some way of holding the spacer still while the bolt turns on it, then nip it up. Just remember that it's not a big strong thread in there!

Failing that, there are proper rivnut tools around.

Just did some a few days ago, a good qualiy set of molegrips to hold the rivnut whilst you crack the bolt is the best way, you'll not grip it tight enough with pliers.If you're around the cardiff area let me know as we've got a rivnut tool in the shop.

Thread revival (been in Canada for 3 weeks). Thanks guys, mole grips it is then, doesn't seem an awful lot to get hold of mind! Whats the worst that could happen…..