Best 180/160 CL Rotors- Mtbr.com
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  1. #1
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    Best 180/160 CL Rotors

    I'm building up a lightweight race wheelset, Berd XC25s, and I need some rotors to put on them. I'm running Formula R1Rs and using Formula Centerlocks on my other wheelset. What are everyone's recommendations for light weight rotors for this setup?

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  2. #2
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    Hmmm.

    Best, as in best combination of weight and braking ability?

    XTR (RT-MT900) are hard to beat. Sturdy, not terribly heavy, and they actually slow you down.
    Death from Below.

  3. #3
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    Quote Originally Posted by Le Duke View Post
    Hmmm.

    Best, as in best combination of weight and braking ability?

    XTR (RT-MT900) are hard to beat. Sturdy, not terribly heavy, and they actually slow you down.
    XTs won't fit in the caliper without rubbing. Are XTRs any thinner? With the R1Rs my biggest limiting factor is traction at the contact patch honestly.

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  4. #4
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    Quote Originally Posted by tuckerjt07 View Post
    XTs won't fit in the caliper without rubbing...
    Are you certain the pistons are pushed all the way in?
    Are the pads pushed back evenly and squarely?

    The XT (RT81) rotors I have measure 1.69-1.72mm thick (same as my XTR rotor).
    Are some of the Formula rotors thinner?

  5. #5
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    Quote Originally Posted by levity View Post
    Are you certain the pistons are pushed all the way in?
    Are the pads pushed back evenly and squarely?

    The XT (RT81) rotors I have measure 1.69-1.72mm thick (same as my XTR rotor).
    Are some of the Formula rotors thinner?
    They have to be. All I did was swap rotors and the drag went away. The Shimano stuff was much worse than the typical didn't retract all the way Formula tisk tisk. Plus you can just hammer the lever and it'll usually stop it, not so with the Shimano stuff.

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  6. #6
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    Quote Originally Posted by tuckerjt07 View Post
    They have to be. All I did was swap rotors and the drag went away...
    Are you absolutely sure it's not an alignment issue?
    Have you measured the rotor thicknesses?

    Easy test if you don't have a digital measuring caliper:
    Remove the rotors and slide them into the brake caliper.
    If the Formula fits and the XT drags you have your answer.
    If the XT fits then you need to adjust the brake caliper alignment.

  7. #7
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    Quote Originally Posted by levity View Post
    Are you absolutely sure it's not an alignment issue?
    Have you measured the rotor thicknesses?

    Easy test if you don't have a digital measuring caliper:
    Remove the rotors and slide them into the brake caliper.
    If the Formula fits and the XT drags you have your answer.
    If the XT fits then you need to adjust the brake caliper alignment.
    That's what I just said I did. The XTs don't fit. Hence why I asked the question about the XTRs.

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  8. #8
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    Quote Originally Posted by tuckerjt07 View Post
    That's what I just said I did...
    Oh, got it. I assumed "All I did was swap rotors" to mean that you tried them mounted on the wheel.

    My suggestion above was to test fit with the rotors off the wheel to make sure.

  9. #9
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    Quote Originally Posted by levity View Post
    Oh, got it. I assumed "All I did was swap rotors" to mean that you tried them mounted on the wheel.

    My suggestion above was to test fit with the rotors off the wheel to make sure.
    I went and dug my caliper out. As I said the XTs are thicker the Formulas. It was obvious when attempting to align the XTs they were never going to work.

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  10. #10
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    Quote Originally Posted by tuckerjt07 View Post
    I went and dug my caliper out. As I said the XTs are thicker the Formulas. It was obvious when attempting to align the XTs they were never going to work.

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    The pistons/pads have to be reset in the caliper, you realize the difference in thickness on rotors in general is in the tenths of a millimeter?

  11. #11
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    Quote Originally Posted by MessagefromTate View Post
    The pistons/pads have to be reset in the caliper, you realize the difference in thickness on rotors in general is in the tenths of a millimeter?
    Yes, I am aware. However, I went the opposite direction of what would have required them to reset but I digress. I don't know why this has gotten sidetracked onto this. Let's rephrase it to exclude any Shimano rotor.

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  12. #12
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    From what I could dig, Formula rotors are 1.6mm thick. This is less than most others.

    https://forums.mtbr.com/weight-weeni...l#post12525090

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