Rotors for Saint M810 Brakes?
I just bought Saint M810 brakes for my Trek fuel ex7. I looked on my bike and it has 185mm rotors. The saints say they work with 180mm. Will the 5mm difference be bad? If I need new rotors, which rotors work best with the saints? Thanks!
You don't need new rotors. You may only need a couple washers.
Mount the caliper with the wheel installed, and look into the caliper at the pads. If the rotor sticks up about 2.5mm past the top of the pads, just add 2.5mm of washers under the caliper post mounts.
If the pads are bang on, don't worry about it. I'm gonna guess that you have Avid G2 rotors. These have fairly wide braking tracks, and I believe they are wider than the Saint pads. If the pads fully contact the rotor track and the rotor doesnt scrape inside the caliper, you're good.
If the rotor is heavily used, check its thickness with a caliper or micrometer. Replace it if it wears down to 1.5mm. This rarely happens though, unless it's very heavily used or the pad wears down to the metal backing material and damages the rotor.
It's always a good idea when switching brake pads to scuff the rotor with fine sand paper. Shimano pads come with well finished surfaces so don't worry about that. I recommend sanding the surface of all new Avid pads though. Then make sure to bed the pads in properly by performing many smooth, easy, controlled slows (not stops) before you use the brakes for real.