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  1. #1
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    Disc Brake Lock Up

    Disc brake lock Up problem
    Both of my front and rear disc brake lock up easily with slight press. Last Sunday I hurt myself as the bike flip over while I stopped urgently avoiding a kid in about12mph speed.
    When I contol my motor cycle, the pressure is linerly proportional to the pressure I give and I can control to stop smoothly but not to my MTB. The disc brake of the MTB, it is not propotional, it just lock up instanly with slight pressure during slow speed riding. For bicycling, I used to the v-brake which I can control exactly to stop smoothly and I am new to my MTB disc brake.
    If I ride in high speed, the disc brake does not lock up easily, it starts lock up easily once the bike is in slow speed. So now I cannot conrol to stop smoothly, the wheel just lock up once it slow down to near stop speed. I have not tried disc brake of other MTB, so I really do not know if my MTB disk brake is normal or having problem.
    Is there any problem to my MTB disc brake? IF there is problem, how do I repair or making adjustment so that I can stop smoothly without locking up?
    Thanks for help!

  2. #2
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    What brakes do you have?

  3. #3
    Official ***** Idiot
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    How many fingers are you using to squeeze the lever? You should only need to use one or two. If you're still using three or four like your old V's, then yeah.........you're going to do a somersault when you hit the brakes hard.

  4. #4
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    Not only which discs, but what size rotors?
    "...the people get the government they deserve..."
    suum quique

  5. #5
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    Going up, going down, flat riding? Type of pad compound? Cold brakes, hot brakes?

    Anybody else? I'm sure we can think of a few more variables here.

  6. #6
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    Must be top secret maybe he greased the pads and hit the kid.
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  7. #7
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    I use 2 fingers only. But I used to old style left side front brake, now the one is right side front brake, I do remember to brake the the right hand first in normal situation. Do I have to brake really very slightly each time which is hard to react gently in urgent case? What kind of brake? I have to check when back at home.
    Is it that disc brake really lock up dead easily? Can I made any adjustment to reduce the braking force so it will not lock up dead?

  8. #8
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    Well, until we know what brand and model of brake, what size rotors, what pad compound.........still can't answer you. That all makes a big difference. Shimano and Hayes lock up easier than Avid or Magura. That can reverse, though, if you change to a different pad compound, set the brakes up differently........and if it only does it after a long downhill or a situation where the rotors and fluid are heated up (assuming these are hydros) then they'll lock up easier than if the brakes are cold.

    Try again when you get home. Be specific. Brand and model, not just brand.

  9. #9
    ride hard take risks
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    Hay CW try swapping the levers back to MTB, I grew up with motos but I like the front on the left with a MTB. I was over powering the front then I switched back was much better yet never over powered the rear brake on the right. Strange but it works.
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  10. #10
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    yes, I am cosidering switching the cable. I have to find out if it can be done easily at home.
    About the barand and model, have to check later.
    Thanks!

  11. #11
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    Quote Originally Posted by ChrisWong
    yes, I am cosidering switching the cable. I have to find out if it can be done easily at home.
    About the barand and model, have to check later.
    Thanks!
    Depending on which brake you have you should be able to do a simple swap the right side for the left without cutting or taking apart.
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  12. #12
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    Unless there's an actual mechanical problem with the brakes, it's user error. Just practice and learn your brakes better. I had no problems going from stock 160mm tektros to 203mm BB7s. Just practice threshold braking so you know the limit. Sometimes people make it seem like bikes are so much harder than cars or motorcycles and they're not. I go from a work vehicle which has terrible brakes that I have to mash hard to my '06 TL with good, almost touchy brakes every day and it's easy. Even with the power of these brakes it's hard to imagine going over the bars accidentally on flat ground. Try practicing stopping with the rear tire barely off the ground.
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  13. #13
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    Quote Originally Posted by dogonfr
    Depending on which brake you have you should be able to do a simple swap the right side for the left without cutting or taking apart.
    Pretty much any brake should have enough to swap the levers without removing anything from them. Will have to turn the bars hard, and maybe loosen the bar clamp to slide them a bit, just to clear the lever clamp. Not hard at all. The only time I've had an issue with that is with wide risers with the hoses/cables set up for levers run relatively far inboard. Then I needed to start taking things apart.

  14. #14
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    Quote Originally Posted by heff®
    Pretty much any brake should have enough to swap the levers without removing anything from them. Will have to turn the bars hard, and maybe loosen the bar clamp to slide them a bit, just to clear the lever clamp. Not hard at all. The only time I've had an issue with that is with wide risers with the hoses/cables set up for levers run relatively far inboard. Then I needed to start taking things apart.
    Early models were right and left specific because of the bolt clamp location for the master cylinder.
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  15. #15
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    Several hydros are still left and right specific, the reservoir needs to face up.

  16. #16
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    Quote Originally Posted by heff®
    Several hydros are still left and right specific, the reservoir needs to face up.
    Moto style.
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  17. #17
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    Heff, My disc brake is Hayes Nine. The disc is about 8 in diam with holes on it.I have now switched from using 2 fingers to only one finger on the front brake. Now I do not lock the front tyre anymore. Seems the front brake is ok, but the rear one has loud high tone when brake. I found out that the disc brake really require very slight pressure, even 2 fingers for me is over. So now I use 2 fingers on right side for rear, and only one finger on left, and have to get the habit of using right hand mainly.. I know changing my habit is not a one day thing, I have to do more practice. I still wonder if I have to swap the left and right lever or just change my habit to use right hand rear brake instead.
    By the way, is there any adjustment to he Hayes Nine to tune it to perform better. What grade is the brake Hayes Nine, a medium grade disc brake?
    Thanks!

  18. #18
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    Low-ish end of the XC line. You can upgrade it with carbon levers, ti bolts, other nifty stuff. The only adjustment that I'm aware of on those is the stroke adjustment, small 2mm (I think) on the lever, adjusts the lever stroke to the lever piston.......you can get a looser feel that way, if you're a little too tight for your liking. Some people like the levers to go almost all the way to the bar under hard braking. Other than that, no adjustments. If you don't have one, get a pad spacer for those.......Hayes have a problem with the caliper pistons popping out of the caliper body if the lever gets squeezed while the wheel is out. Not a huge deal, but a pain in the butt to get back in.

  19. #19
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    nines are fine ,drop back to a 6" rotor at both ends to reduce the power a little and just keep practicing amd you will master it . I run my bikes with the front on the left even though my MC is opposite with no problems.

  20. #20
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    The Nines work, old mid level stuff. Switch back to smaller rotors. The only adjustments with the Nines is the lever reach adjustment.

  21. #21
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    Thanks for all the advice!

  22. #22
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    Quote Originally Posted by ChrisWong
    Thanks for all the advice!
    Keep us up to date on your results.
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  23. #23
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    I don't think I can change my left hand rear brake habit easily. So I am considering switching the left and right lever of the Hayes Nine. I have questions on the lever. Is it left/right specific, and does it have to face up? If I switch the lever left/right, the lever will become facing down from the original facing up positon. I don't want to switch the cable instead of the lever as it seems too complicated.

  24. #24
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    Quote Originally Posted by ChrisWong
    I don't think I can change my left hand rear brake habit easily. So I am considering switching the left and right lever of the Hayes Nine. I have questions on the lever. Is it left/right specific, and does it have to face up? If I switch the lever left/right, the lever will become facing down from the original facing up positon. I don't want to switch the cable instead of the lever as it seems too complicated.
    The 9's should be universal, they shouldnt care what side their on.
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  25. #25
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    OK, thanks! I shall switch them as it is simple, loosing the screws will do.

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