I don’t know that Shimano has ever published the difference in the steel alloys they use, but as I understand it the main reason the resin-only rotors are super shitty is the surface treatment.
I can tell you that in practice even with Shimano resin pads they offer less braking power (friction) compared to the same resin pads on good Shimano rotors (I’ve swapped rotors but not pads multiple times on test bikes because, as a general rule, I won’t ride these).
If you do run sintered pads on the resin-only rotors three things happen:
1) They scream for help like you’re slowly filing away their very beings.
2) They warp if you get them proper-hot on a long descent.
3) They wear out fast.
I’ve never done it myself but have seen the results enough times that I’m confident that the ‘resin-only’ stamp should be trusted AND these rotors have not place on mountain bikes of any level.
Feb. 5, 2022, 3 p.m. - Andrew Major
I don’t know that Shimano has ever published the difference in the steel alloys they use, but as I understand it the main reason the resin-only rotors are super shitty is the surface treatment. I can tell you that in practice even with Shimano resin pads they offer less braking power (friction) compared to the same resin pads on good Shimano rotors (I’ve swapped rotors but not pads multiple times on test bikes because, as a general rule, I won’t ride these). If you do run sintered pads on the resin-only rotors three things happen: 1) They scream for help like you’re slowly filing away their very beings. 2) They warp if you get them proper-hot on a long descent. 3) They wear out fast. I’ve never done it myself but have seen the results enough times that I’m confident that the ‘resin-only’ stamp should be trusted AND these rotors have not place on mountain bikes of any level.