mate waqs having a nightmare with **** brake performance. i told him to ride uphill and to ride back down with the brakes pulled lightly on before spraying them with water.

he's now saying i've caused his rotor to deform. he's now bought a new rotor for 25€ (!) rather than bending the old one back into shape….

am i at fault?

yep.

Yea, should have been lots of hard stops to pressurise the pad material as well as heat it in an autoclave stylee. Long slow braking will have glazed pads, then overheated the rotors causing a critical temperature failure in the rotor.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
See, I read STW and learn 🙂

ah…. best keep stumm then.

If he knows nothing about bikes and trusts you for all his maintenance tips then you're at least partly to blame.

If you're simply a friend who made a suggestion then no, he should have a brain of his own. If you said to him 'you can make that 250ft gap jump' would he then blame you for the subsequent injuries he sustained!?