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  1. #1
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    Shimano Ice Tech rotors rub when hot...

    I have a brand new 180mm shimano ice tech rotor on my front XT brake. When the rotor is cool, there is no rubbing. When I go on a downhill and heat it up, it starts rubbing. Then a minute or two later it cools and doesn't rub anymore. Pretty annoying.

    I have had a ton of problems getting these XT brakes (front and rear) with ice tech rotors when trying to calibrate them. It seems like the clearance between the pads and rotors are super tight. I bought the brakes used, so maybe that's the problem; rotors are new. LBS says the rotors are true and the brakes are working as they should. No clue....

  2. #2
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    My Shimano XTR M988 Trail front brake with a 180mm Shimano RT-86 Ice Tech rotor does the same thing on descents. There's a reasonable amount of pad/ rotor clearance normally and the brake doesn't rub apart from after it's been used on a descent.

    Love the new 2012 XT brakes

    Bleeding the front brake didn't fix the problem.

  3. #3
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    Quote Originally Posted by car bone View Post
    Could it be that the extreme thermal expansion of the aluminum is causing this?
    Hard to say...but I would have to set my caliper to be rubbing cold in order for it not to rub when its hot....the rotor is as true as I can get it. Doesn't seem right.

  4. #4
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    Could it be that the extreme thermal expansion of the aluminum is causing this?
    Rule #9 // If you are out riding in bad weather, it means you are a badass. Period.

    Quote Originally Posted by iheartbicycles View Post
    Specialized sucks ass.

  5. #5
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    Time paradox!
    Rule #9 // If you are out riding in bad weather, it means you are a badass. Period.

    Quote Originally Posted by iheartbicycles View Post
    Specialized sucks ass.

  6. #6
    bt
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    thermal expansion of the mineral oil?

    The volume of a given oil mass increases with temperature, therefore, its density decreases. The degree of expansion is expressed as the coefficient of thermal expansion. Thermal expansion is useful to determine the size of a container needed when the oil will be heated. Inexperienced people often have an oil overflow because of a surprising amount of thermal expansion.

  7. #7
    007
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    Quote Originally Posted by bt View Post
    thermal expansion of the mineral oil?
    This. Can you switch to braided lines? Makes me wonder if all the gizmo's and gadgets for "improved cooling" (e.g., fins, etc.) are a necessity for functionality. On the new Saints, even the friggin' rotors have "cooling fins."
    Alcohol may lead nowhere, but it sure is the scenic route!

  8. #8
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    Quote Originally Posted by OO7 View Post
    This. Can you switch to braided lines? Makes me wonder if all the gizmo's and gadgets for "improved cooling" (e.g., fins, etc.) are a necessity for functionality. On the new Saints, even the friggin' rotors have "cooling fins."
    I'd say they are trying to keep the whole system cool; cool rotor doesn't provide a heat input to warm the oil, etc.
    "It looks flexy"

  9. #9
    007
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    Quote Originally Posted by gticlay View Post
    I'd say they are trying to keep the whole system cool; cool rotor doesn't provide a heat input to warm the oil, etc.
    I agree completely . . . but what I'm wondering is whether or not the added cooling provided by all their "technology" is a forethought for improved performance, or an afterthought to ensure functionality.
    Alcohol may lead nowhere, but it sure is the scenic route!

  10. #10
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    Dunno but I run the Saint 4-pots and they don't have that issue.... just sayin'
    "It looks flexy"

  11. #11
    007
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    Quote Originally Posted by gticlay View Post
    Dunno but I run the Saint 4-pots and they don't have that issue.... just sayin'
    And I run Hope's (M4/X2) and they ALSO don't have that problem . . . the question for you is do you have the latest and greatest Saint's with the cooling fins on the pads and rotors, or do you have the previous gen Saint's?
    Alcohol may lead nowhere, but it sure is the scenic route!

  12. #12
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    Quote Originally Posted by OO7 View Post
    And I run Hope's (M4/X2) and they ALSO don't have that problem . . . the question for you is do you have the latest and greatest Saint's with the cooling fins on the pads and rotors, or do you have the previous gen Saint's?
    Old style with older than old style discs (the plain round ones on one bike and some Magura's on the other).
    "It looks flexy"

  13. #13
    007
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    Quote Originally Posted by gticlay View Post
    Old style with older than old style discs (the plain round ones on one bike and some Magura's on the other).
    So if the old style didn't need cooling fins to keep the fluid from expanding to the point of pushing out pads, and many other brands don't need them either, I wonder if perhaps the redesign of the Shimano MC's doesn't allow for the same expansion in fluid arising from high temps as the old design. And hence, in order to remain functional they had to develop additional cooling methods?

    I dunno . . . I abandoned engineering years ago.
    Alcohol may lead nowhere, but it sure is the scenic route!

  14. #14
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    Quote Originally Posted by OO7 View Post
    So if the old style didn't need cooling fins to keep the fluid from expanding to the point of pushing out pads, and many other brands don't need them either, I wonder if perhaps the redesign of the Shimano MC's doesn't allow for the same expansion in fluid arising from high temps as the old design. And hence, in order to remain functional they had to develop additional cooling methods?

    I dunno . . . I abandoned engineering years ago.

    Alcohol may lead nowhere, but it sure is the scenic route!
    So now just Beer-gin-eering?
    "It looks flexy"

  15. #15
    007
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    Quote Originally Posted by gticlay View Post
    So now just Beer-gin-eering?
    Yeth ossifer. Thath cuuurrrect.
    Alcohol may lead nowhere, but it sure is the scenic route!

  16. #16
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    Coef. of thermal expansion

    Maybe because steel and aluminum have different coefficients of thermal expansion; the aluminum grows faster than the steel and causes a small amount of warping of the rotor.

  17. #17
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    I'm assuming you are using the current XT calipers with the finned pads?

  18. #18
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    Same problem as above and changed to Formula 180mm rotor for front and problem fixed!
    I took time to break/bed the Shimano rotor in properly etc but warped first hard descent.
    Just change the rotor.
    Its definetly a problem.
    BTW the 160 on the rear has stayed perfect!!

    PS Never had this problem with previous rotors Shimano ever!!

    PS again running with new XT brakes and PLENTY clearance commpared to other brands, thats not the issue
    Ti ML Lover

  19. #19
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    Quote Originally Posted by VTgrinder View Post
    Same problem as above. I took time to break/bed the Shimano rotor in properly etc but warped first hard descent.
    Makes you wonder just what kind of testing goes on before a company launches a new product. Makes me think the extent of product testing is done indoors in a lab and not under actual riding conditions.

    How'd you like to find out here:

    Red Bull Rampage Winning Run - Kurt Sorge 2012 - YouTube

    Hank

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