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  1. #1
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    hydros and winter riding

    this will be my first winter with hydros , usually ride year round here in new england . will i have a problem with the hydros in extreme cold , will the fluid freeze or thicken to the point it will cause a braking issue. also do not know if it matters have what i believe are low end hydros(tektro agulia comp's)

  2. #2
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    Pretty certain that the fluid won't freeze . . .think about your car for example. It may thicken up a bit though, but as soon as you get in a few stops I imagine you'll heat up the rotors and fluid enough to keep it from causing a problem.

    I'm new to hydro's as well though, so more experienced folks may say otherwise.

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    Good thread here! Just bought my first ride with hydros too. Was wondering if storing in an unheated garage was OK. I plan to ride all winter but didn't want to ask the nooblike question first.

  4. #4
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    I have ridden hydro's in temps as cold as -6 Fahrenheit without any issues what so ever .

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    Quote Originally Posted by AZ.MTNS
    I have ridden hydro's in temps as cold as -6 Fahrenheit without any issues what so ever .
    That's all I needed to know for my Pennsylvania winters.

  6. #6
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    DOT 3/4/5.1 brake fluid has a much lower freezing point than Mineral oil.

    The freezing point of Mineral oil is around -22 degrees and DOT brake fluid is around -60 degrees, however, I have read that the lowest USEFUL temp due to fluid viscosity is around 30 degrees, just below freezing. I have read reports of mineral oil based brake systems not providing adequate stopping power at these temps. But YMMV.

    However, you should be fine whether you have brake fluid based brakes or mineral oil based brakes. Just be c

  7. #7
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    As a general rule, shimano brakes do not work in winter (real winter). All other brakes do work. But YMMV, of course.

  8. #8
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    Shimano brakes use mineral oil. Most others use a DOT fluid. I used my Elixir CR (Avid) through a Minnesota winter of night riding down to -10 deg F without any problems other than excessive squealing of rotors when snow contacted warm rotors.
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  9. #9
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    Quote Originally Posted by frdfandc
    DOT 3/4/5.1 brake fluid has a much lower freezing point than Mineral oil.

    The freezing point of Mineral oil is around -22 degrees and DOT brake fluid is around -60 degrees, however, I have read that the lowest USEFUL temp due to fluid viscosity is around 30 degrees, just below freezing. I have read reports of mineral oil based brake systems not providing adequate stopping power at these temps. But YMMV.

    However, you should be fine whether you have brake fluid based brakes or mineral oil based brakes. Just be c

    Total BS I have ridden Shimano brakes in temps as low as -35 C without problems.....that is with there standard mineral oil.

  10. #10
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    Quote Originally Posted by shapirus
    As a general rule, shimano brakes do not work in winter (real winter). All other brakes do work. But YMMV, of course.

    Total BS I have ridden shimano brakes down to -35C with standard mineral oil and had no problems.

  11. #11
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    People may get confused about how well their type of hydros work in cold weather if their system is not properly bled, which can be a common issue, even with a factory bleed.

    While liquids expand/contract very little due to temperature changes, any air that is in the system will be affected much more. If you have excess air in part of your system, you might not realize it until you ride in colder temps in which the air contracts and reduces the total fluid volume in the system, giving you mushy or non-existant braking.

    Keep in mind that both gases and liquids are fluids.

    If you ever get caught off guard by mushy brakes, pumping the lever rapidly is your best bet (this will heat up the fluids and cause the air to expand).

    A well bled hydro brake system will function properly in any temps in which you dare to ride.

    -Pete
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  12. #12
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    Quote Originally Posted by Pedalphile
    People may get confused about how well their type of hydros work in cold weather if their system is not properly bled, which can be a common issue, even with a factory bleed.Yup bleeding is very much an issue

    While liquids expand/contract very little due to temperature changes, any air that is in the system will be affected much more. If you have excess air in part of your system, you might not realize it until you ride in colder temps in which the air contracts and reduces the total fluid volume in the system, giving you mushy or non-existant braking.Well they both contract and the result is that the reservior level drops quite a bit so if you catch it you just top up, if you miss it it is a bleed

    Keep in mind that both gases and liquids are fluids.

    If you ever get caught off guard by mushy brakes, pumping the lever rapidly is your best bet (this will heat up the fluids and cause the air to expand).

    A well bled hydro brake system will function properly in any temps in which you dare to ride.

    -Pete
    Stabbing the brakes works also when the rotors get a thin film of ice on them...can happen in a snowfall with big flakes....or bombing through a puddle then back into the cold.

    The rotor has almost zero friction, so no heat so the ice film doesn't melt...can take 200 feet to get any braking at all...

    Solution hammer the brakes on and off and the ice will shatter of the rotor.
    Last edited by jeffscott; 09-28-2010 at 02:25 PM.

  13. #13
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    Quote Originally Posted by Pedalphile
    While liquids expand/contract very little due to temperature changes, any air that is in the system will be affected much more. If you have excess air in part of your system, you might not realize it until you ride in colder temps in which the air contracts and reduces the total fluid volume in the system, giving you mushy or non-existent braking.
    Eh? No offense but let me get this straight - you're theorizing that someone might not realize that they have so much air in their hydraulic brakes that the reduction in volume of that air in extreme cold could cause brake failure? Here on Earth?

    It seems more likely to me that if someone doesn't realize they have air in their brakes it's because there's only a tiny bubble present. I can't imagine that a COLD hydraulic brake with air in it is going to be significantly worse than that same brake when it's warm. Rather the opposite - logically the hydraulic performance should improve ever so slightly in the cold (until increased viscosity causes it's own issues).

  14. #14
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    So the real question here, is what the hell are people doing riding when its -35C?!!?

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    Quote Originally Posted by OO7
    So the real question here, is what the hell are people doing riding when its -35C?!!?

    Commuting my ride is about 20 minutes one way, and I usually beat traffic when it gets cold cause the roads are so bad.

  16. #16
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    the issue with shimano brakes (at least in the past) was not so much the fluid type, but rather slow/inconsistent pad retraction due to either caliper seal QC or caliper seal material type.

    i had a set that would either hang one caliper, or have an extremely firm lever feel after a few pumps, mainly at 40F and below. Never had mushy brakes in the cold. When the sticky caliper syndrome was solved in the Shimano line, I think this problem went away, too.
    Civilization ends at the waterline. Beyond that, we all enter the food chain, and not always right at the top.

  17. #17
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    Quote Originally Posted by cjn1014
    the issue with shimano brakes (at least in the past) was not so much the fluid type, but rather slow/inconsistent pad retraction due to either caliper seal QC or caliper seal material type.

    i had a set that would either hang one caliper, or have an extremely firm lever feel after a few pumps, mainly at 40F and below. Never had mushy brakes in the cold. When the sticky caliper syndrome was solved in the Shimano line, I think this problem went away, too.

    Mine are 2006 XTR, I rode a pair of 2005 Deores (I think) the deores had less of the sticky piston problem than the XTRs do.

  18. #18
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    Magura HS33 hydraulic rim brakes are terribly slow in the cold... at around -10c they're slow enough that I didn't want to ride my bike.. but the one issue with my setup is.. it's a trials bike.. so the rear brake has to be very quick on/off action...

    My DOT fluid brakes however always worked fine in the cold, except for the cold weather and snow made them squeal like mad.

  19. #19
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    Quote Originally Posted by Clones123
    Eh? No offense but let me get this straight - you're theorizing that someone might not realize that they have so much air in their hydraulic brakes that the reduction in volume of that air in extreme cold could cause brake failure? Here on Earth?

    It seems more likely to me that if someone doesn't realize they have air in their brakes it's because there's only a tiny bubble present. I can't imagine that a COLD hydraulic brake with air in it is going to be significantly worse than that same brake when it's warm. Rather the opposite - logically the hydraulic performance should improve ever so slightly in the cold (until increased viscosity causes it's own issues).
    No offense taken.

    The problem is that air isn't just oxygen and nitrogen - it also contains water vapor. Drop the temp enough, and that water can change state from gas to liquid, greatly decreasing it's volume.

    Just as a car's tires will lose pressure in the cold, so will any brake system containing air.

    My brakes never felt like they needed a bleed until I started using them in the cold.

    Whether you agree or not, air in a hydro brake system is never a welcome thing.
    I can barely get my mouth around it.

  20. #20
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    Quote Originally Posted by OO7
    So the real question here, is what the hell are people doing riding when its -35C?!!?

    If you are unaware, jeffscott is our local "I've done it all" resident. Just do a quick search and you'll see.



    Quote Originally Posted by jeffscott
    Total BS I have ridden Shimano brakes in temps as low as -35 C without problems.....that is with there standard mineral oil.

    If you slow down and re-read what I posted, I never stated that they will not work in extreme temperatures. Just posting what I've read from what others have experienced and what the freezing point is.

    Hence the YMMV.

  21. #21
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    Quote Originally Posted by Pedalphile
    The problem is that air isn't just oxygen and nitrogen - it also contains water vapor. Drop the temp enough, and that water can change state from gas to liquid, greatly decreasing it's volume.

    Just as a car's tires will lose pressure in the cold, so will any brake system containing air.
    Your physics analogies are getting worse. You're now proposing that when water vapor precipitates out of air, the air and now separated liquid water then take up significantly less volume? Consider: If I charge up an air tank with humid air and let it sit for a couple of days until some water accumulates in the bottom of the tank, it's not like the pressure in the tank is going to change, at least not significantly.

    While you're correct that a gas changes either pressure or volume (or both) with changes in temperature, the analogy doesn't work because a brake system isn't statically pressurized like a tire is. Also, it's not like that unnoticed air bubble in the brake fluid is going to shrink in the cold and create a vacuum in the brake line.

    I don't mean to be a jerk but your assertions just don't make sense. What few issues there are with mineral oil brake systems in the cold have nothing to do with air bubbles, containing traces of water vapor or not. Air in a hydraulic brake line is bad for performance whether it's cold or warm.

  22. #22
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    When you're compressing air in a tank, the gaseous water is being turned to liquid via the pressurization, therefore your compressor is measuring the pressure of the air with the water already in liquid form.

    What happens if you heat the compressed tank of air? Higher pressure. If the temp changes, the pressure does as well. If you cool the tank you will lose pressure.

    Don't believe me? Remove the safety valve from your hot water heater and allow the water to boil. You'll experience some drastic expansion. This is an extreme example, but still an example of what happens when liquid changes to gas or vice versa in a closed system.

    The only difference in a hydraulic brake system is that it is mostly liquid with a small amount of gas in my example, but regardless of whether the pressure in that closed system is starting at 1000psi or 0, cooling the gas in that system will lower the starting pressure and therefore affect brake feel/performance to a degree proportional to the temperature delta and the total amount of gas in the system. It is entirley analogous to the air compressor example, except you overlooked a crucial factor in your example.
    I can barely get my mouth around it.

  23. #23
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    Quote Originally Posted by tmhar28
    this will be my first winter with hydros , usually ride year round here in new england . will i have a problem with the hydros in extreme cold , will the fluid freeze or thicken to the point it will cause a braking issue. also do not know if it matters have what i believe are low end hydros(tektro agulia comp's)
    Yes they should work fine, the lever may have a slightly different feel but you'll probably not notice too much due to numb fingers and thick gloves.

  24. #24
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    Been riding in the winter for 40 years or so, since I was 10. Coaster brake for many years.
    The coaster brake didn't care about winter.

    My hydro/winter use has been "sticky". I ride where it can be -10F and the puddles not frozen. The silt from the river floods is very dark and full of decaying matter. A lot of heat from the sun and decay. Ride through one and the water freezes between the piston, before the seal, and the bore.

    I've used mx1 and bb5,7 during the winter and only had the cable freeze. If I force heavy grease up into the bottom of the cable it usually doesn't freeze up. Those who keep the brakes hot probably don't have issues with hydro's. I have a set of Julies and the master leaks down when it gets below +20F, so no matter how hot they get, it won't help them.

    I can't see any brake fluid thicken up enough to be an issue. But seals can get hard, restricting retraction of the pads and issues with master leak down.

  25. #25
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    Quote Originally Posted by Pedalphile
    When you're compressing air in a tank, the gaseous water is being turned to liquid via the pressurization, therefore your compressor is measuring the pressure of the air with the water already in liquid form.

    What happens if you heat the compressed tank of air? Higher pressure. If the temp changes, the pressure does as well. If you cool the tank you will lose pressure.

    Don't believe me? Remove the safety valve from your hot water heater and allow the water to boil. You'll experience some drastic expansion. This is an extreme example, but still an example of what happens when liquid changes to gas or vice versa in a closed system.

    The only difference in a hydraulic brake system is that it is mostly liquid with a small amount of gas in my example, but regardless of whether the pressure in that closed system is starting at 1000psi or 0, cooling the gas in that system will lower the starting pressure and therefore affect brake feel/performance to a degree proportional to the temperature delta and the total amount of gas in the system. It is entirley analogous to the air compressor example, except you overlooked a crucial factor in your example.
    Gas law stuff, STP and all you are correct. It applies to brakes only if you keep the brake applied while all the other stuff is going on. When one releases the brakes the volume will reset through the master.

    Water heater thermostats only will go to 160F unless its a commercial heater.
    Steam has 1600 times the volume of liquid water.
    Water expands 1 gallon for each 40 gallons heated 100F.
    44lbs/sq in @ 100 ft elevation
    Enough about water.

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