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  1. #1
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    Shimano mineral brake fluid: hygroscopic?

    Does Shimano's brake fluid absorb water?

    I understand that it has a lower boiling point to DOT fluid, is supposedly more environmentally friendly and doesn't peel paint off at 40 paces, but does it also absorb much less (or no) moisture?

    Thanks

    Wombat

  2. #2
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    Quote Originally Posted by Wombat
    Does Shimano's brake fluid absorb water?

    I understand that it has a lower boiling point to DOT fluid, is supposedly more environmentally friendly and doesn't peel paint off at 40 paces, but does it also absorb much less (or no) moisture?

    Thanks

    Wombat
    The water will never mix in with the oil. The problem is if you get water in the line it is heavier than the oil, will go down the line to the caliper, get hot and boil. At which point your brakes fade.

    If I am wrong about that someone please correct me, but that is my understanding of water mixing with the mineral oil.

  3. #3
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    Thanks. That makes sense. I guess my concern is whether there is a need to change the fluid every couple of as you are meant to do with brake fluid in cars. When you don't you eventually rust out the calipers and the same will probably happen with the calipers on bikes, although perhaps the mineral oil ones are less prone to this.

    Wombat

  4. #4
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    Quote Originally Posted by Wombat
    Thanks. That makes sense. I guess my concern is whether there is a need to change the fluid every couple of as you are meant to do with brake fluid in cars. When you don't you eventually rust out the calipers and the same will probably happen with the calipers on bikes, although perhaps the mineral oil ones are less prone to this.

    Wombat
    I would probably just stick with bleeding them every year or two (possibly less) if the lever feel is good. I don't think I have bleed my rear brake for about 3 years and it is still running strong. If you got a significant amount of water in the system your braking would go to crap. It is a safe bet that if your brakes are performing well and the lever feel is good, then there is no water in the line. You would notice the loss of braking power/feel before the water had a chance to rust your calipers.

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