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  1. #1
    Senior Member d2create's Avatar
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    Need help adjusting disc brakes

    Hi, i just picked up my Kona Dew Deluxe with mechanical disc brakes and both wheels will not free spin for more than a second or two because one of the pads on the disc brake is contacting the rotor. It's the outside pad (farthest from the wheel).
    How do you adjust these things? I've never had disc brakes before. I searched, but couldn't find any answers.

    Thanks!
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  2. #2
    Digs technical steeps
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    Quote Originally Posted by d2create
    Hi, i just picked up my Kona Dew Deluxe with mechanical disc brakes and both wheels will not free spin for more than a second or two because one of the pads on the disc brake is contacting the rotor. It's the outside pad (farthest from the wheel).
    How do you adjust these things? I've never had disc brakes before. I searched, but couldn't find any answers.

    Thanks!
    I've got Hayes hydraulics on my Kona but I suspect they adjust similarly. Here's what I do and it works great: With the wheel in place I loosen the bolts that hold the brake caliper to the fork mount, wiggle the caliper to loosen it up a little, then squeeze and release the brake lever 4 or 5 times to center the pads on the rotor, holding the brake lever squeezed the last time while I tighten down the bolts securily. Works every time for me.
    Last edited by Juniper; 10-09-04 at 06:52 PM.
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    Senior Member d2create's Avatar
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    hmmmm..... maybe mine work differently? I just tried that and it didn't work.
    2008 Rivendell A. Homer Hilsen
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    Senior Member d2create's Avatar
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    OK, with more fooling around i was able to loosen the screws and pull the caliper away from the wheel as far as possible and it seems to just clear the rotor by a fraction of a hair! Both wheels seem to spin pretty well now.

    But i have another question... the braking power doesn't seem to be as powerful as the rim brakes i'm used to. Seems almost impossible to lock the wheels while riding. Tends to just slow them to a stop. How am i supposed to do a power slide stop? haha. Seriously though, should the power of disc brakes be the same, more, or less than rim brakes?
    2008 Rivendell A. Homer Hilsen
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  5. #5
    Digs technical steeps
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    <<<OK, with more fooling around i was able to loosen the screws and pull the caliper away from the wheel as far as possible and it seems to just clear the rotor by a fraction of a hair! Both wheels seem to spin pretty well now.

    But i have another question... the braking power doesn't seem to be as powerful as the rim brakes i'm used to. Seems almost impossible to lock the wheels while riding. Tends to just slow them to a stop. How am i supposed to do a power slide stop? haha. Seriously though, should the power of disc brakes be the same, more, or less than rim brakes?>>>



    My experience has been that I had to adjust them this way a few times for them to find their 'sweet spot' (area of least resistance), and that a very minor amount of rubbing is almost inevitable; never enough to come close to slowing down the wheel, just enough to make a little occassionably noticeable rubbing noise. That goes away as the pads wear in. The key to adjusting them, for me, was to pressure the brake lever several times while the caliper was loose (attached with the mounting bolts loosened a little but not being held by my hand) so that the caliper could float and the pads naturally found their place on the rotor, then tighten down the caliper while keeping the pads locked on the rotor via the brake lever.

    The stopping power on my discs is 100%. If I apply full pressure at the levers the wheels stop instantly. There is a saying about discs that the only thing between the bike at speed and a complete stop is the gripping power of the tire treads on the riding surface. I mean instant stop!

    When my bike was new I was not getting that instant stopping action. I had to break in the pads and burnish the rotors by riding and braking, ride a little - brake half way, ride a little - brake completely, ride a little - brake half way, ... . I found a nice long hill and used the brakes at about half power on and off all the way down. Pretty soon I noticed the rotor was burnished and the brakes were rock solid.

    When my pads were new I cleaned the burnished section of the rotors with common isopropyl (rubbing) alcohol. Don't get any grease or oil or anything else on the burnished (braking) section of the rotors except the rubbing alcohol or you will ruin the pads.

    Good luck! Let us know how it works out and if you have any other problems with them. After riding with discs I doubt I'll ever go back to wheel rim brakes. People ride my bike with the discs and get a look of astonishment at how well they work and feel. Granted, a lot of rim brakes aren't set up right or the pads are shot but I've never ridden rim brakes that were such a pleasure as the disc's.
    Last edited by Juniper; 10-10-04 at 12:15 PM.
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  6. #6
    Senior Member MudPie's Avatar
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    Quote Originally Posted by d2create
    OK, with more fooling around i was able to loosen the screws and pull the caliper away from the wheel as far as possible and it seems to just clear the rotor by a fraction of a hair! Both wheels seem to spin pretty well now.

    I have Hayes hydraulics and I had the same issue - I just cleared the disc when the mount is at the extreme position and when the pads and disc were brand new. After a few rides, that gap will open up. I agree with the other post on increased brake efficiency as the pads and rotor become "matched".

    I predict in a few days, you'll be saying "why didn't I get these sooner?" I do mainly XC and find all I need is one finger to control my downhill speed. Also, I am able to brake later (as when approaching a turn), and I'm saying "Oh, sh*t" with much less frequency.

  7. #7
    I drink your MILKSHAKE Raiyn's Avatar
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    Quote Originally Posted by d2create
    Hi, i just picked up my Kona Dew Deluxe with mechanical disc brakes and both wheels will not free spin for more than a second or two because one of the pads on the disc brake is contacting the rotor. It's the outside pad (farthest from the wheel).
    How do you adjust these things? I've never had disc brakes before. I searched, but couldn't find any answers.

    Thanks!
    I'm feeling remarkably lazy tonight due to a LONG weekend, so if you tell me what brand and model of mechanical disc they are then I can get you the right information

  8. #8
    Chairman of the Bored catatonic's Avatar
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    I have shimano deore mechs, and here's how I aligned them right.

    Items needed:
    allen key of the right size (its going to be metric)
    good lighting (i used the good ole sun!)
    good pair of eyes (my eyes suck, so basiacally my level or better will do)

    What I did was turn the bike upside down, and loosen the calipers at the mount points on the fork/frame, then moved the caliper until i could see light on both side of the disc, then tighten (while watching to make sure the caliper doesnt twist while the mount is being re-tightened). Once you are done, that should be it. Ten minutes towards smooth rolling. Just BE SURE THAT YOUR WHEELS ARE ON STRIGHT BEFORE DOING THIS, otherwise you'll have to do it over.

    Deore discs pretty much have jack squat for adjustment options, and I think Rayin can tell you how bad the manuals for Deore mechs suck (really I've seen better manuals for saddles).

    As far as braking power, it takes a while to break them in, took me a month, but oh my god do they stop...you will endo on these things if your not careful. Back wheel locks up very easily, and the front has enough deceleration that my fork is well within it's travel under hard braking.

  9. #9
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    "Just picked up my..." Return it to the shop and have the mechanic repeat the brake set-up, and walk you through the process.

  10. #10
    la vache fantôme phantomcow2's Avatar
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    well i actually had hte same issue when i got disc brakes for the first time, i was so annoyed becuase people were saying how good they are and mine sucked. Well then i sat down and adjusted it and now im quite happy with their stopping power. The htign ii find with disc brakes is they are very very touchy, you really have to get that adjustement just right for the best performance. What i like to do is have about one playing cards clearance between the rotor and pads, and have it so they activate after pulling on the lever for 1/2 inch. After i did that i tried squeezing the brakes on a hill (im not a total idiot its that before i did these few steps i could squeeze it all i wanted and it would hardly stop me) and i found myself doing a flip

  11. #11
    Senior Member d2create's Avatar
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    Quote Originally Posted by gruppo
    "Just picked up my..." Return it to the shop and have the mechanic repeat the brake set-up, and walk you through the process.
    Yes, but it was sunday and they were closed. And this shop is pretty far from me. The only Kona dealer in my area.
    So since i needed to commute on monday, i had to fix it myself. Not only were the discs farked up, but the drivetrain was all noisy and not shifting right, and both wheels were out of true! Whoever set this bike up did a s**t a$$ job!

    But i'm all good now! Thanks for the replies! Just working the discs through brake-in now.
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    This old thread was really helpful for adjusting my disc brakes, but have some tips to contribute that only clarify some of the previous contributions and might save someone time down the line. Goes to show that good tips are timeless. I'm a noob on this forum, so take it easy.

    Was looking up how to adjust my disc brakes because the brake pads in both my front and rear brakes were rubbing up on the rotor and causing drag while I was riding my bike. It's a relatively minor amount of drag, so I didn't notice immediately after I purchased the bike. Although it was a brand new bike purchased from my LBS, when I took it back to them, the staff were unhelpful at diagnosing the issue. They said the drag would go away eventually, but the problem persisted.

    I have Shimano Deore hydrolic disc brakes and the Shimano disc brake manual is craptastically bad (as noted by a previous post). There are two mount points on the disc brake. The first mount point connects the bike's fork/frame to the adapter. The second mount point connects the adapter to the caliper. It's the second mount point that you want to adjust.

    Turn the bike upside down and avoid touching the rotor with your bare hands (the oil from your skin will reduce the stopping power of the disc brakes ever so slightly). You can always use rubbing alcohol to clean the rotor. Loosen the screws connecting the second mount point (adapter to caliper). You only need to loosen the screws to the point that the caliper is adjustable. Pump the brake handle to center the caliper. When you look at the caliper, there should be a sliver of light shining through on both sides of the rotor. Spin the wheel to confirm that there's no friction. Now hold down the brake handle while tightening the screws.
    Last edited by Blargy; 06-25-08 at 11:16 PM.

  13. #13
    Senior Member Cadfael's Avatar
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    With some mechanical disc brakes... one pad should always be 'just' touching the rotor... you should hear a slight scraping as you turn the wheel. It should not be enough to actually slow you down.... just the lightest of touches.

    One pad will static, the other pad will the one that moves across and pinches. You can generally adjust the static pad by some screw or other adjustments mechanism... it depends upon the calliper manufacturer. It could be your LBS has intentionally set the static pad to close to the rotor to allow for wear over the first few weeks of use, similar to the way they also may set normal rim brakes to be very keen and make them last longer without need for adjustment.

    I accept that some mechanical callipers will be designed that both pads move toward the rotor, but as far as I know the most common method is for only one pad to move.

  14. #14
    Pwnerer Wordbiker's Avatar
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    Quote Originally Posted by Cadfael View Post
    With some mechanical disc brakes... one pad should always be 'just' touching the rotor... you should hear a slight scraping as you turn the wheel. It should not be enough to actually slow you down.... just the lightest of touches.
    I disagree.

    Given a true rotor, mechanical brakes should still not rub the pad. Minimal clearance should be set for the static pad, but rubbing is unacceptable.
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  15. #15
    Senior Member BCRider's Avatar
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    On the mechanical brakes I've used there's no doubt that the overall performance was far better when the fixed pad has a very light scuff sound. We're talking hardly any at all mind you. Just enough to know that there's zero gap but not enough to slow anything at all. When they were set like that the lever feel was instant and flex free.

    And when set with just barely any scuff it's not long before the pad wears just that hair's worth and then it's quiet.
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  16. #16
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    Quote Originally Posted by Cadfael View Post
    With some mechanical disc brakes... one pad should always be 'just' touching the rotor... you should hear a slight scraping as you turn the wheel. It should not be enough to actually slow you down.... just the lightest of touches.
    Quote Originally Posted by Wordbiker View Post
    I disagree.

    Given a true rotor, mechanical brakes should still not rub the pad. Minimal clearance should be set for the static pad, but rubbing is unacceptable.
    I could go either way. The rub typically happens when I'm off the bike, adjusting the brakes. I adjust until I hear the slightest rub. When I'm on the bike, the weight displaces the bike somewhat, eliminating the rub. I like my brakes nice and tight, not sloppy where I must squeeze the trigger through a wide range of motion.

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    Senior Member Cadfael's Avatar
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    Quote Originally Posted by Wordbiker View Post
    I disagree.

    Given a true rotor, mechanical brakes should still not rub the pad. Minimal clearance should be set for the static pad, but rubbing is unacceptable.
    It is how the manufacturers recommend you set them up, I accept this does not apply to all types, but for some it IS the correct way.

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    Maybe they want the pads to wear out sooner, so they can sell more replacements...

  19. #19
    Senior Member smurf hunter's Avatar
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    Took me quite a long time to learn how to maintain my disc brakes when I got my Dew Deluxe a few years back.
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    I've got Shimano mechanicals (M495 which takes the M08 pads). On these, both pads move, that is there is no static pad. Rather than adjusting the caliper body, I've found that by using the barrel adjuster and bringing the pads slightly in or out the rotor does not rub on the pads and I still have good braking power and no rubbing.

    Unfortunately my brakes squeal a lot when applied. I'm probably going to change the pads this weekend and noticed the horrible (already mentioned) Shimano tech doc, if you can call it that, on this. I've messed around with them before and have not been able to easily get the old pads out, the tech doc of course has minimal info on this. Any one have tips on this?

    Also, just curious how many miles you get out of your pads.

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    Senior Member Cadfael's Avatar
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    Quote Originally Posted by kramnnim View Post
    Maybe they want the pads to wear out sooner, so they can sell more replacements...
    A valid point!

    But... it is a fact that on my 'owd MTB, the braking is better when the static pad is 'just' touching the rotor. If you think about it make sense. If one pad it static... and both are equidistant from the rotor, then when you brake either the rotor has to deflect for both pads to contact it, or the whole calliper assembly has to bend or flex... putting strain on the fork bosses. Logic to me dictates the static pad has to be as close as possible to the rotor to have the best braking power. I stress again, this is for systems that have a static pad, other systems may be different. It also cannot be stressed enough... the static pad it 'JUST' touching the rotor... not rubbing. Rubbing would produce fiction, and some noise that could be heard when riding, and whould have some braking action. If I lift the the wheel and spin the wheel I hear nothing. But if I put my ear real close and turn the wheel slowly I hear just the lightest of scraping.

    My commute is only 10 miles there and back... but I do it five days a week, and when I had my brakes serviced a few weeks ago at my LBS he told me the pads were good for another few months... and that was after two years from new.

  22. #22
    Pwnerer Wordbiker's Avatar
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    I often defy manufacturer's instructions.

    I also tear the tags off my pillows and remove "warranty void if removed" tags. I'm a rebel.
    Quote Originally Posted by ahsposo View Post
    Ski, bike and wish I was gay.

  23. #23
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    I have mechanical disc brakes where one pad moves and the other is static. The static pad should not touch or rub on the rotor. It should be as close as possible without touching the rotor period. That way when the pad that moves deflects the rotor, it will hit the static pad instantly. If you want less lever throw - thats what I like - adjust the moving pad the same as the static pad. As mentioned in other posts disc brakes are very touchy and you may have to tinker with them to get it just right.

  24. #24
    Senior Member Cadfael's Avatar
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    Quote Originally Posted by Paul3003 View Post
    I have mechanical disc brakes where one pad moves and the other is static. The static pad should not touch or rub on the rotor. It should be as close as possible without touching the rotor period. That way when the pad that moves deflects the rotor, it will hit the static pad instantly. If you want less lever throw - thats what I like - adjust the moving pad the same as the static pad. As mentioned in other posts disc brakes are very touchy and you may have to tinker with them to get it just right.
    No... trust me... it should just be scraping. It takes some getting 'your head around'... but that is how it should be set up.

  25. #25
    Senior Member BCRider's Avatar
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    For SINGLE MOVING PAD style brakes Cadfael has it right. And it's simple physics on this issue and not some blind adherance to the instructions or open to ignoring this because of some desire to buck the system. Tear your labels of those pillows and defy the pillow police if you must but set your single sided disc calipers as he says.

    If there is a significant gap then before the brakes can begin to slow you down the moving pad has to flex/bend the rotor over to the fixed pad and then further deflect it so it is squeezed between the two pads. If you're using some of your lever effort for flexing the disc then that's energy that isn't being used to slow you down.

    WHen I was running Hayes HMX1's even the pad wear over the course of a few days of riding opening up this disc to fixed pad gap would result in noticably reduced braking force and a spongy feel at the lever. Adjusting the fixed pad to a barely scuffing point restored the performance.

    This same issue will be found in the newer (and cheaper) single moving pad hydraulic calipers or any other caliper where the caliper has one fixed pad and where the body is rigidly fixed to the mounts. This need for regular adjustment as the pads wear is what finally made me bite the bullet and go for double piston hydraulic setups.
    Model airplanes are cool too!.....

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