Andrew's got it… I've generally found that Shimano Ice-tech rotors will work well with any brand of brakes… your experience may vary.
One more up-prop for mAndrew. The Shimano Ice-Tech rotors are better at temperature management (in real life, qualitatively and quantitatively), which does improve brake performance. If you've purchased new brakes, putting new rotors on will help you maximize performance out of the gate.
One note on this: I find for ShoreXC riding I ditch the alloy centre rotors (like IceTech) in the winter and this year I even tried going down a rotor size on the front (mixed results) as I was finding my brakes weren't heating up enough to perform optimally.
Results may vary of course, but if your brakes are already being water cooled like here in a Shore-To-Sky winter it's questionable that there are benefits to the, quite a bit more expensive, Ice Tech setup.
I'm an advocate of swapping to basic steel rotors for the winter and running IceTech when heat management is important. Definitely save you $$$ long term and it's quick to swap.
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