the aftermarket anodised chainring bolts on my XT chainset were starting to creak a bit so I decided to check them out.

two are a bit loose, but the other two are pretty firm. they were originally put in with a dab of threadlock.

whilst turning one of the firm ones, there was a bright flash followed by a nice smell of burning… pretty impressive stuff.

has anyone else had this happen?

😯

Cool, was it flammable lube+heat from pressure?

do you live in a flinty area? might have been a shard of flint being crushed under pressure.

I think you might have got an atom trapped in there and split it. Don’t undo the bolt again – all hell will be let loose. Personally I’d been concerned about riding a bike with a broken atom in it, if I were you I’d keep quiet about it and sell it on the classifieds to someone you don’t know, preferably a few counties away.

I had this tightening up a bolt on my disk brake mount. I almost thought I’d imagined it until I smelt the burning. Very weird I thought.

Ti bolts, if you have ano ti bolts, often bind and crack with a burning smell. Not sure of the reasoning TBH

small concentration of magnesium maybe
I think a fair few alloys have magnesium

that is probably complete nonsense though

Thermite?

I had a similar thing when removing a pedal the night before going on a bikey holiday; when the thing eventually came loose it was with an almighty “crack” and the house absolutely stank for ages afterwards!

my kcnc bolts used to do that, the smell was like that from a cap gun

why can’t all bolts do that? 🙁

yep, I’ve had the same with KCNC chianring bolts.
I assumed they had binded !?!?!?

I’ve had the same with Ti bolts/ ali rings. Small flash and smelt like Nov 5 afterwards.

would make a useful alternative to torque settings.

“Tighten until it goes bang”

[video]http://www.youtube.com/watch?v=G2qCyxiOzVQ[/video]

wwaswas – Member

would make a useful alternative to torque settings.

“Tighten until it goes bang”
Wrong wrong wrong.
Tighten until it goes bang, then back off 1/8th of a turn.