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  1. #1
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    Cold temperatures

    I've been told that mineral oil used by Shimano gels at sub-zero temperatures and the brakes therefore lose effectiveness. This is not true of automotive brake fluid used in Elixirs.
    Does anyone have experience with this?

  2. #2
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    Quote Originally Posted by asmac View Post
    I've been told that mineral oil used by Shimano gels at sub-zero temperatures and the brakes therefore lose effectiveness. This is not true of automotive brake fluid used in Elixirs.
    Does anyone have experience with this?
    I have ridden Shimano XTR brakes and -36C....no noticable gelling they work fine...

    As it gets colder and the brakes got older (2007 model) they will tend to leak a little fluid.

  3. #3
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    Thanks... I guess I was told wrong. There's nothing like actual experience.

  4. #4
    dru
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    Some of the Shimano brakes will fail, others will not. My '08 XTRs will fail (blown seals) according to my friends who've cooked theirs. However my 02 Deores have been perfectly fine. I'm talking winter weather, below freezing. It isn't actually a problem with the shimano fluid but a problem with the seals on some models and years.

    Drew
    occasional cyclist

  5. #5
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    I believe Shimano fluid is just plain old mineral oil. If it does gel I suppose that would increase the pressure in the system and could blow the seals. It makes sense that this would only affect some models with weaker seals. Does anyone have specific experience with newer XTs in below zero f conditions?

  6. #6
    dru
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    Quote Originally Posted by asmac View Post
    I believe Shimano fluid is just plain old mineral oil.
    No, it is absolutely not just mineral oil. I found that out the hard way.....

    There's a little warning on the bottle about skin and eye irritation.....

    and you know, a couple hours into assembling and bleeding brakes I've got the crap all over both hands and my face.....

    had a 'sunburn' for about 3 days after......

    Drew
    occasional cyclist

  7. #7
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    Interesting. I thought plain, non-corrosive mineral oi was a Shimano selling point. Can someone clarify exactly what is in that stuff?

  8. #8
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    I had a pair of 2009 Shimano M775 Brakes fail in temperatures colder than 34 degrees. There was definitely a problem and Shimano replaced the calipers for free. I still think that new ones don't work as well in the cold though.

    The first set the levers would pump up and eventually leak oil and contaminate my pads. First couple of shops just looked at me funny when I told them what happened. Finally found a shop who saw similar posts on MTBR and helped me contact Shimano.

    I have friends with older and newer model XT and XTR brakes and they do not have any problems.

  9. #9
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    3 of 3 pair of XTR brakes all leaked at 15 to 20F. I believe their product manual even states that they are not to be used in the cold.
    =========================================
    Minnesota Off Road Cyclists www.morcmtb.org

  10. #10
    dru
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    Quote Originally Posted by asmac View Post
    Interesting. I thought plain, non-corrosive mineral oi was a Shimano selling point. Can someone clarify exactly what is in that stuff?
    It is mineral oil based. Shimano's selling point was that it wasn't DOT type brake fluid. DOT brake fluid isn't corrosive btw, but destroys paint. Obviously us cyclists want to keep the paint as nice as that on our cars. The Shimano stuff is fine on paint.

    Drew
    occasional cyclist

  11. #11
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    It is LHM oil, which happens to be what Citroen use in their hydraulic system too.
    It's usually green.

    The old Magura rim brake manuals used to have a reference for oil types.
    That ended when they figured it paid off to sell small bottles of it at a premium.

    Quote from the manual:
    Castrol LHM 1756
    Pentosin LHM
    Hanseline H-LP 10



    Magura

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