My non disc XTR brakes on Mavic rims never stop screeching. LBS has worked on them twice. Better but not great. I've tried myself tilting them foward and rearward. Lightly sanding the rims and cleaning them with alcohol. Picking out he pads and roughing them up. Better but never quiet. I've replaced the Shimano pads twice and have also tried Richey red pads. No help. Is it the length of the pads that cause the noise because of vibration? Is there a way to put road pads on the xtr brake assemblies? Are some pads better than others in noise level?