yesterday, after 1000 m downhill on a easy gravel road (smelly brakes then) my taurine started to squeal ( hi pitck crack like noise) when i push hard on my back brake.
it happens also when i am out of the saddle and seems to come fron the back part, then propagates to the entire frame as well....

it hard to detect, but i get a check to the rear brake support and the disk and all seems ok...

what is this??

how i detect the source??
it was very similar ot the one i got on the saddle post till the mechanic put me some carbon fitting paste and the all was ok!!