Wriggly creaky cranks

I recently developed a hideous creak in my cranks (stronglight 2000 on the stronglight 400 BB). Following stripping everything back to the fram and a visual inspection to make sure nothing sinister was happening, reassembly had cured the creak.

However, riding for more than 5km now seems to be inducing the creak which i think is due to the crank bolts loosening. I tighten they loosen!

What the shit am i missing?

swap pedals - ride
swap cranks - ride
swap bottom bracket - ride

maybe the bottom bracket is knackered, you've removed and cleaned and replaced but that still doesn't take into account the BB might be knackered /. pedals spindles might be knackered

see which of these switches clears up the creak

otherwise a drop of oil around the knee and ankle areas might be required

What torque value did you tighten them to. #chuckles

In my head i tighten the crank bolts to precisely the correct torque. In reality i have no idea and may well have over tightened them, tapers look fine however.

Thanks for the suggestions Dicki, i will give this a go but I am almost certain the noise is the cranks slipping on tapers as the bolts loosen. I would like to think the cranks and BB are fine as they have only done 200 miles so far after replacing a miche set which survived multiple winters and did 10,000 miles without whinging at all.

really appreciate yours and hippy's input getting very frustrated!

It's the softer cranks that are the thing that will be damaged and you're not likely to be able to eyeball the damage. Tiny smear of grease and tighten to correct torque is how I do it. Tighten then loosen over and over again just ruins the cranks. You're sure the noise is from the cranks?

Ah hadn't thought about it from that side of things!

the creak and clicking feeling is removed once the crank bolts are tightened and when it returns the crank bolts are loose again hence my thinking this is the origin. I will try out the other suggestions as well however. Hope i havent mangled my cranks!

shimano cranks and shimano BB ?
you are not trying campy cranks on a shimano BB ? or vice versa

It sounds like your cranks have worn internal tapers, and are moving on the spindle. Once they do this they are pretty much toast, as they will always move a bit and wear some more, so the alloy becomes loose on the spindle again. The bolt is then loose too.
There isn't really a cure, apart from replacing them.

nope its stronglight cranks on stronglight BB.

yep pretty much convinced this was over tightened cranks.

shit.