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  1. #1
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    winter brake performance

    I have a '13 specialized camber, the brakes are stock. Riding this summer the brakes were great, I was very happy with them. But now that I have been riding quite a bit this winter, the brakes absolutely suck. The lever feels the same, but there is no stopping power. It feels like the stopping power is ~25% of what they were during the summer. I tried cleaning the rotors with rubbing alcohol, but that didn't seem to make any difference. Any ideas on whats up?
    DaveH
    '15 Salsa Horsethief
    '13 9:ZERO:7
    '13 Trek Domane
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  2. #2
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    Dave, Hard to know without looking at them. It is possible that the pads have either glazed or become contaminated. I would clean them with alcohol, sand them lightly with 400 grit paper, reclean them (being careful that you don't touch them) and then reburn-in your rotors and see if that helps. Otherwise the next thing I'd check is a different pad compound.

  3. #3
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    What brakes do you have?

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  4. #4
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    Quote Originally Posted by davesupra View Post
    I have a '13 specialized camber, the brakes are stock. Riding this summer the brakes were great, I was very happy with them. But now that I have been riding quite a bit this winter, the brakes absolutely suck. The lever feels the same, but there is no stopping power. It feels like the stopping power is ~25% of what they were during the summer. I tried cleaning the rotors with rubbing alcohol, but that didn't seem to make any difference. Any ideas on whats up?
    Often brakes will leak a little when it gets cold...thus oil on the pads...

    Also they won't get hot enough to self clean it it gets really cold especially with all the salt etc...

    Try putting the pads in a fry pan on medium heat...wait til they stop smoking then gently sand off the carbon and gunk...re-install and go bed them in.

    Winter is very hard on brakes...what typ of brakes ans riding are we talking about here.

  5. #5
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    dot or mineral?


    never mind, i just did a googling of your brakes and see you have mineral. i bet this is the answer, as mineral can't withstand cold as dot can. mineral gets thick in the cold

  6. #6
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    Thanks for the tips everyone. I'll start by cleaning/lightly sanding the pads and see what that does, and go from there. Whats the best way to re-bed the pads? I'll post back with the results afterward.

    Yes, I have mineral oil in the lines, the pads are stock as far as I know (I bought the bike used). My riding has mostly been quick riding on bike paths, a small amount of rougher off-road stuff, and one winter off-road race that was some xc and some river riding. It has been cold here, I usually don't ride when it's much colder than ~5 F, most of my winter riding is in the 15-20 F temp range.
    DaveH
    '15 Salsa Horsethief
    '13 9:ZERO:7
    '13 Trek Domane
    '16 Salsa Fargo

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    Quote Originally Posted by fishwrinkle View Post
    dot or mineral?


    never mind, i just did a googling of your brakes and see you have mineral. i bet this is the answer, as mineral can't withstand cold as dot can. mineral gets thick in the cold
    My XTR's run mineral oil and they work fine at -30 C.....they have leaked a bit below -20 C though

  8. #8
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    Your lucky, my xt got so stiff I couldn't pull the lever in -5C weather. I put the Elixirs bank on and solved that problem. Now I just have shitty brakes and turkey warble problem.

    Sent from my SGH-I337M using Tapatalk
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    Norco Fluid 9.2 29er FS
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  9. #9
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    Quote Originally Posted by fahza29er View Post
    Your lucky, my xt got so stiff I couldn't pull the lever in -5C weather. I put the Elixirs bank on and solved that problem. Now I just have shitty brakes and turkey warble problem.

    Sent from my SGH-I337M using Tapatalk
    What ever the problem was it was not the oil getting thick.

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    Quote Originally Posted by jeffscott View Post
    What ever the problem was it was not the oil getting thick.
    Chiming in as a fluids engineer here. Mineral oil is approx. 10x more viscous than DOT4 over the temperature range of -40C to 100C. However, the viscosity of DOT4 and mineral oil both increase as temperature drops by about the same factor.

    In my view there is no clear advantage of DOT4 to mineral oil in 'freezing weather', and I agree with jeffscott from a technical perspective. If anybody disagrees, can you please provide the technical rationale? I am happy to post supporting calculations and references but am avoiding becoming overly-technical here unless useful.

  11. #11
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    just going on real life experience. i have both and my shimano zee's are definitely more laggy than my avid xo's in cold temps south of 20*F and when its north of freezing the zee's start to come to life. maybe seals contract differently in the shimano's. idk, but it's def noticeable.

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    Thanks, the experience is interesting. Being in Southern California I have never tried cold weather riding. Curious if some water in the line could be freezing? As you know the downside to mineral oil is that any significant water will exist as a separate phase.

    I just ordered the 1-L bottle of Shimano fluid, will do some lab tests on it and Hayes DOT4 fluid over the next month including multiphase separation and ice formation at low temperatures.

  13. #13
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    yeah that would be awesome, as i am running shimano mineral and auto store dot4.

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    I run the Shimano oil in my Shimano brakes and Dot 5 in my hopes, my own experience here. All my Hopes work as normal in what ever - temp I ride in, all my Shimano breaks before stiff and hard as hell to even pull once it drops below -5 C. I would say yeah it was the brake but both front and back acted the same and this has happened on every single Shimano brake I have used over the past 5 years.

    Make sure when you do your temp test you use small clear tubing the same diameter we use for brakes.
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    Quote Originally Posted by fahza29er View Post
    Make sure when you do your temp test you use small clear tubing the same diameter we use for brakes.
    Good point about hose diameter. For constant lever force, the piston displacement rate will vary with the square of hose diameter.

    One key relationship is that piston displacement rate will vary with 1/mu where mu is the viscosity (likely minor details omitted here for simplicity if anybody is checking).

    What I am curious to find is:
    i) At what fraction water does each fluid form a separate water phase or ice phase at cooler conditions.
    ii) What is the actual viscosity=f(T) of Shimano mineral oil fluid between -10C up to 100C. I assume its properties differ from non-proprietary mineral oil.
    iii) Given i-ii above, is the Shimano fluid inferior to DOT4 given typical system geometry and usage conditions.

  16. #16
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    I took my calipers off and found that the inboard piston on the front brake was leaking. I cleaned everything up extremely well and put it back together, but it's too cold to go for a test ride now. Any guess if they are going to continue to leak, or do you guys think they will be ok once the weather warms up?
    DaveH
    '15 Salsa Horsethief
    '13 9:ZERO:7
    '13 Trek Domane
    '16 Salsa Fargo

  17. #17
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    DS, good question. There are a lot of relationships at play here (different materials contract at different rates with dropping tempratures, seals can stiffen under temp extremes, oil viscosity changes, etc.) Did you notice a seal installed improperly or rolled out of position by the cold? Was there any damage to the caliper or piston? If it still leaks it will be in warrenty until the one year point (an additional year if you purchased it with most credit cards). I'd warm it up and check it. If it's still leaking I'd get to a bike shop and get a warranty replacement or repair started.

  18. #18
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    Quote Originally Posted by Forster View Post
    DS, good question. There are a lot of relationships at play here (different materials contract at different rates with dropping tempratures, seals can stiffen under temp extremes, oil viscosity changes, etc.) Did you notice a seal installed improperly or rolled out of position by the cold? Was there any damage to the caliper or piston? If it still leaks it will be in warrenty until the one year point (an additional year if you purchased it with most credit cards). I'd warm it up and check it. If it's still leaking I'd get to a bike shop and get a warranty replacement or repair started.
    I didn't actually pull the piston out of the caliper, I just used rubbing alcohol, paper towels and q-tips and cleaned everything up real well. I'm not the original owner, so I don't think the warrantee is transferable?
    DaveH
    '15 Salsa Horsethief
    '13 9:ZERO:7
    '13 Trek Domane
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  19. #19
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    Quote Originally Posted by davesupra View Post
    I took my calipers off and found that the inboard piston on the front brake was leaking. I cleaned everything up extremely well and put it back together, but it's too cold to go for a test ride now. Any guess if they are going to continue to leak, or do you guys think they will be ok once the weather warms up?
    Mine have sealed back up for the last 8 winters.....Actually they leak when it gets cold like -15 C and seal back up somewhere around -10C....something like that.

  20. #20
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    Quote Originally Posted by jeffscott View Post
    Mine have sealed back up for the last 8 winters.....Actually they leak when it gets cold like -15 C and seal back up somewhere around -10C....something like that.
    That's good news, I hope mine do the same.
    DaveH
    '15 Salsa Horsethief
    '13 9:ZERO:7
    '13 Trek Domane
    '16 Salsa Fargo

  21. #21
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    Dave, what brakes are you talking about ?
    Do we have to Google or guess, or can you just tell the brand and type of your brakes ?

    Avid will leak when temp drops below freezingpoint. The seals in the calipers get hard and fluid poors out when you use the breaks.
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  22. #22
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    Quote Originally Posted by thasingletrackmastah View Post
    Dave, what brakes are you talking about ?
    Do we have to Google or guess, or can you just tell the brand and type of your brakes ?

    Avid will leak when temp drops below freezingpoint. The seals in the calipers get hard and fluid poors out when you use the breaks.
    They are the stock Tektro Draco 2 brakes that come on the Camber. I'm guessing thast you have the Avid brakes, did yours seal up again once it got warm? Thanks,
    DaveH
    '15 Salsa Horsethief
    '13 9:ZERO:7
    '13 Trek Domane
    '16 Salsa Fargo

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