1. The most important thing about buying a new bike is to make sure it fits. The only way you'll know if the bike is right for you is to size up the bike and make sure that the bike's geometry matches your body's geometry. Ask questions and do some research.
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2. If possible, try to find a shop that will let you demo the bike on real dirt. Five minutes in a parking lot won't cut it. You wouldn't buy a car without a real world test drive, and a bike should be no different.
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  1. #1
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    Overheating the disc brakes

    Hi,

    i'd much appreciate your opinions on disc brake noises (mostly like a constant howling), when they overheat. All of you ride trails, easy or difficult, uphills or downhills, rocky or not.
    The trail i have been on recently, is an around 8-10 min trail, and the first 4-5 min there's a huge narrow and rocky downhill. As u can understand, there is no chance u let the front brake loose. If u do so you are gonna 100% crash on a tree.

    I ride a hardtail (Cube) with Deore XT's (BL-M785) and in these first 4-5 min, the front brake started making this big noise, like a howling. From what i think and i have asked some guys in a specialised shop, they said because of the overheating this noise is just normal. Truth is the brakes were pushed to the limits.

    Is this normal or what?
    I ordered my bike 1 month ago. Because it's a 2012 model and it was in stock in a store in another city, i think maybe some expert should check the pads or something. Don't tell me about rotors being aligned, of course i have checked them since the first week.

    thx, waiting for your same experiences and thoughts !

  2. #2
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    2012 XT brakes are the 'stuff"

    Get bigger rotors or metallic pads or both or use your brakes less.

    Also see Brake noise (Deore XT)
    Last edited by mitzikatzi; 11-01-2012 at 12:38 AM.
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  3. #3
    wyrd bi ful rd
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    Have you 'bed' you brakes in ...

    Get yourself up to speed and brake firmly without locking. Release your brakes before you come to a complete stop. Do it again another 20 times. Then change to the other brake. Would suggest you extend your arms and put your weight over the rear wheel if braking the front as you would not want to go over the bars ... unlikely that you would but just in case ... Then let the brakes cool down before riding again.

  4. #4
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    the noise comes only when i go to this specific downhill. On the road i run like insane and press the break and nothing is being heard. I have the bicycle for 1 month, the brakes are bedded in dude...

  5. #5
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    Check out this thread, third and sixth post: Brake noise (Deore XT)

    Seriously though, you need to learn to control the heat in your brakes. If you can't then they're going to get hot and make noise. Some trails you just can't stay off the brakes long enough to cool them down. I got to ride a really fun trail a few weeks back that I hadn't ever rode and it was really steep for around 5 miles. My brakes heated up and started to howl a little but every time I stayed off the brakes and let them cool they would stop making noise.
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  6. #6
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    Since you havent noted any decrease in stopping ability and its only noise, its perfectly normal. Keep Riding.

  7. #7
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    Quote Originally Posted by ins@ne View Post
    Hi,

    i'd much appreciate your opinions on disc brake noises (mostly like a constant howling), when they overheat. All of you ride trails, easy or difficult, uphills or downhills, rocky or not.
    The trail i have been on recently, is an around 8-10 min trail, and the first 4-5 min there's a huge narrow and rocky downhill. As u can understand, there is no chance u let the front brake loose. If u do so you are gonna 100% crash on a tree.

    I ride a hardtail (Cube) with Deore XT's (BL-M785) and in these first 4-5 min, the front brake started making this big noise, like a howling. From what i think and i have asked some guys in a specialised shop, they said because of the overheating this noise is just normal. Truth is the brakes were pushed to the limits.

    Is this normal or what?
    I ordered my bike 1 month ago. Because it's a 2012 model and it was in stock in a store in another city, i think maybe some expert should check the pads or something. Don't tell me about rotors being aligned, of course i have checked them since the first week.

    thx, waiting for your same experiences and thoughts !
    Your weight matters and your rotor size...a 220lbs riding a 6-inch rotor is probably gonna have problems...

    Try stabbing the brake.....On for 1 sec off for as long as possible...alternate front and rear so one brake is always on...

    Get a bigger rotor....did the rotor turn blue or brown that is a cooked brake....sometimes you need to use some fine grit sandpaper to tae off the glaze....

    We have 20 min steep rocky downhills around here practise makes perfect.

  8. #8
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    thx all

  9. #9
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    i am 191-194 lbs (87-88 kg) and my front rotor's size is 180mm (7 inch). I think it's pretty good dude !

  10. #10
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    Before I bed new rotors, I lightly sand them down with 400 grit emery cloth followed by fine (1000 grit) sandpaper along the circumference where the pads contact the rotor. This helps the pads break in since most disc surfaces are ground somewhat perpendicular to the axis (actually in an arc but it appears to be a straight line since the grinder and rotors are both rotating when this is done). Smoothing this out allows new pads break in faster since it has more even contact with the rotor. It also rounds off sharp edges on the rotor holes/slots.

    Use the brakes intermittently. You can't simply hold on to the brakes while rolling downhill for more than 30 seconds or more. Pulse the alternately (front and back) and it will help the brakes cool off.

    You may want to get a 203mm front rotor too.

  11. #11
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    180 front rotor is perfect for your size.. Throw some resin pads on there(f01a pads) and you'll be fine I'm betting... Also be sure to be using your rear brakes to balance the bike and rotor temps.. Also check and make sure your pads arnt contaminated or glazed.. If they are, sand em back to fresh pad, clean the rotor and reinstall= then rebed and see how that works.. My rears sequel like a stuck pig=resin pads got things quiet again...

  12. #12
    rebmem rbtm
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    The bike has XT-785 brakes and photos I've seen of this bike show that it doesn't have the Ice Tech rotors or Ice Tech finned pads.

    If you want the brakes to run cooler then get the following:

    Ice Tech Finned Resin Pads - F01A
    or
    Ice Tech Finned Metal Pads - F03C

    and

    200mm 6-bolt Ice-Tech Rotor - SM-RT86-L
    180mm 6-bolt Ice-Tech Rotor - SM-RT86-M
    160mm 6-bolt Ice-Tech Rotor - SM-RT86-S
    or
    200mm CenterLock Ice-Tech Rotor - SM-RT81-L
    180mm CenterLock Ice-Tech Rotor - SM-RT81-M
    160mm CenterLock Ice-Tech Rotor - SM-RT81-S

  13. #13
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    thx that was helpful.
    i want to ask u sth. The price of the new XTR's involve both brakes (rear and front) or the price goes x2?

  14. #14
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    hi i have tektro draco brakes on giant revel 1..can any1 help me the front disc makes a slight grinding noise when it turns how do i fix this??...

  15. #15
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    Quote Originally Posted by madloo08 View Post
    hi i have tektro draco brakes on giant revel 1..can any1 help me the front disc makes a slight grinding noise when it turns how do i fix this??...
    Can you describe the noise better? Is it a light scraping sound or something louder? Are you feeling any resistance if you turn the wheel by hand?

    -S

    Sent from my DROID4 using Tapatalk 2

  16. #16
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    Quote Originally Posted by shibiwan View Post
    Can you describe the noise better? Is it a light scraping sound or something louder? Are you feeling any resistance if you turn the wheel by hand?

    -S

    Sent from my DROID4 using Tapatalk 2
    yes light scraping when in rotation like metal on metal so to speak..can not seem to narrow down to one place either sounds the same all round dont think disc is warped with bike only being about 3 month old...if u ask my opinion i would say not aligned but im a noob with disc brakes and thats how i would put it in simple terms

  17. #17
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    Quote Originally Posted by madloo08 View Post
    yes light scraping when in rotation like metal on metal so to speak..can not seem to narrow down to one place either sounds the same all round dont think disc is warped with bike only being about 3 month old...if u ask my opinion i would say not aligned but im a noob with disc brakes and thats how i would put it in simple terms
    Try this quick preliminary procedure to re-align your calipers to the disc.

    1. Slightly loosen the two Torx screws (T25 size) holding the brake caliper to the post mount or mounting adaptor. Make sure the brake caliper can jiggle around freely once the screws are loosened.

    2. Spin the wheel by hand (the noise would seem to be louder at this time).

    3. While the wheel is spinning, squeeze the brake lever firmly and stop the wheel. Do not let go yet.

    4. Holding on to the brake lever, tighten up the two caliper mounting screws. You can let go of the lever after the mounting screws are tightened.

    5. Spin the wheel again - the noise will be reduced somewhat.

    If the noise is reduced except for one spot, then you need to true the brake disc.

    Here's a video by Shiggy (one of the mods on this forum) on how to true the brake disc.
    rotor truing - YouTube

    Give it a go and let us know how it turns out.

    -S

  18. #18
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    thank you for your help will try 2moz and let you know if better seen videos on youtube of how to do

  19. #19
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    Bah... got negged for helping. $&%#&@!!!

  20. #20
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    hi done this 2day is huge improvement thanks...problem now it still does it ever so slight in one spot how do fine tune that??

  21. #21
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    Quote Originally Posted by madloo08 View Post
    hi done this 2day is huge improvement thanks...problem now it still does it ever so slight in one spot how do fine tune that??
    Watch the video i posted earlier about how to true your brake rotor!

    -S


    Sent from my DROID4 using Tapatalk 2

  22. #22
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    Quote Originally Posted by SB Trails View Post
    180 front rotor is perfect for your size.. Throw some resin pads on there(f01a pads) and you'll be fine I'm betting... Also be sure to be using your rear brakes to balance the bike and rotor temps.. Also check and make sure your pads arnt contaminated or glazed.. If they are, sand em back to fresh pad, clean the rotor and reinstall= then rebed and see how that works.. My rears sequel like a stuck pig=resin pads got things quiet again...
    Sorry to the OP, not trying to thread jack. I weight 205 and have 160mm rotors with Avid juicy 3's. From what it sound's like I need larger rotors, true?

  23. #23
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    Quote Originally Posted by ins@ne View Post
    thx that was helpful.
    i want to ask u sth. The price of the new XTR's involve both brakes (rear and front) or the price goes x2?
    I have the XT-M785 brakes, and I had rear brake noise descending a very steep section of trail that in my scared state of mind required applying both brakes for longer than 5 minutes. I ended up glazing the rear brake pads, and I had to replace them. So I switched to an Ice Tech Rotor in the same size(160mm), and on that section of trail I didn't anymore noise problems. However, when I crashed and bent the spider arm of a fairly new Ice Tech rotor (and had to remove it to get back to the trailhead), I wasn't happy having to spend $60 to replace it. I also followed the advice given here and learned to switch between front and rear braking while doing long steep descents. I found that if I had enough traction so that I was really braking hard, then it was also possible to alternate between front and rear braking.

    I am using the Ice Tech metal pads(FO3C) in the front and the resin pads(FO1A) in the back--only because MBA said the resin pads were just as good as the metallic pads, and the resin pads are cheaper.
    Last edited by happyriding; 11-10-2012 at 07:13 PM.

  24. #24
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    Quote Originally Posted by MTBerNick View Post
    Sorry to the OP, not trying to thread jack. I weight 205 and have 160mm rotors with Avid juicy 3's. From what it sound's like I need larger rotors, true?
    If your not happy with your current braking then "true" try a bigger rotor. J3's are not the strongest brakes out there.
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  25. #25
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    thank u so much silent now

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