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Thread: brake rotors

  1. #1
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    brake rotors

    I bought some 160mm KCNC Razor rotors for a build I'm working on (see this thread for details), but I'm starting to worry over whether using lightweight rotors is a good idea.

    Where I live it's possible to descend for many miles with no flat or uphill sections to cool the brakes. One local ride involves about 6 miles of descent, with an average grade of 9% and some sections over 20%. There are longer ones around. I'm starting to think maybe I should be going with beefier rotors, like Icetechs.

    I'm 155 lbs. Add 3L of water in a hydropack for long summer rides, tools, spare stuff, and that's maybe 9-ish pounds more. I ain't young, and falling at speed in your late 50's is a different thing than when you're younger. Slower and harder to recover, and you may never get back to 100%.

    Does anybody have experience with the KCNC Razor rotors on long (say, 4+ mile) descents? Obviously you don't want to ride them constantly, but sometimes due to steepness you have to be on the brakes quite a bit of the time. Should I buy some Icetechs instead? Or maybe an Icetech front, KCNC rear? Or upgrade to a 180mm front? I ride down similar inclines on a road bike, but it's got rim brakes, so I don't have a feel for disks. Dunno if I should even worry.

  2. #2
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    Carbon rotors could be a good choice, they are made to work better when hot. M785's and above are finned and will run cooler.

    Mark
    2012 XXL Carve Expert

  3. #3
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    I am 160 lbs. and my backyard trail has 2000 feet of elevation drop in about 5 miles. I run Hope Evo X2 brakes with 160mm Alligator Windcutter rotors and organic pads on my Flux. My brakes never really get a chance to cool down. You will definitely feel more fade with lightweight rotors and lighter calipers, but it shouldn't deter you from running them if you are not constantly on the edge of out of control. I'm 43 and a former XC racer that weighed about 15-20 lbs. less a decade ago, but I can still get down the hill with the best of them.

    I found thicker and heavier rotors will have more bite, but you have to try different rotors (and probably pads) to see what works for you. I experimented with many rotors and pads until I found the setup that I like best for my dry desert conditions. I have never tried the Icetech rotors because it looks like the braking track is a little small for the my large X2 pads. Like everyone else, I would like to try a reasonably priced carbon rotor when they come out, but my current set up performs well for now.

  4. #4
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    What do you mean "when they come out"