Originally Posted by
msu2001la
I have XT (MT-800) rotors on one wheelset and cheaper Shimano RT-56 rotors on another. Both are used with GRX brakes - the only difference I notice is that the XT rotors are louder and have a bit more "bite", and make more of a loud "zing zing" after hard stops (which goes away after a few seconds).
same type of pads on both bikes ? (should be resin on the bike with the RT56 rotors)
if the bike with the XT / MT800 rotors has metal / sintered pads - this could account for the additional sound (?)
I have prev gen XT (RT81) rotors on one bike and RT56 rotors on another bike - both with resin pads - and the XT / RT81 combo is quieter (and has much better feel / power )