LTIH: discovered that my new-ish Ultegra cranks for the roadie (3mo or so) were creaking abominably, after ruling out all the other usual suspects the hard way (reinstalling BB and cranks et al). Discovered that only one of the four crank bolts were loctited (looks like a factory mistake), and every single bolt had backed off to be finger-loose other than the one that had been installed with loctite. So, pulled them out, cleaned the bores and bolts with isopropyl, applied loctite and started to reinstall with a torque wrench since you need a surprising amount of torque on some light bolts. Bang, broke off the head of the very first bolt (must have been stressed by its time running loose). Literally the first time that's ever happened to me because I am normally a pretty patient mechanic and don't like to brutalise my stuff. Luckily was able to get it out with a normal drill bit, since I didn't have any left-handed bits or a remover tool lying around. So much goddamn faffing to make the bike shut up.