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  1. #1
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    Yet another disc brake thread

    Sorry guys, as I'm sure you get plenty of first-time posters whining about disk brakes here. But my friendly neighbourhood bike shop is too far away to drive + drop off the cycle to for a tuning when a DIY jobber might cure all.

    Having purchased a Specialized Hardrock Comp Disc four days ago, equipped with Hayes MX-2 mechanical discs, I'm having some problems already (go figure) that I believe go beyond the lines stretching. The first and foremost is the rubbing that occurs b/w the disc and the pads when the (primarily) front wheel is spinning. When I wail the front brake hard, and this is the scary part, the whole front wheel kind of tilts to the left (the side of the wheel on which the disc is mounted). It's worrying stuff, mostly because I'm a disk newb. I've already readjusted the brake lines a couple of times due to stretching. Before going all out and making this more confusing than it has to be, any ideas?

    Thanks in advance!

  2. #2
    Senior Member Brian's Avatar
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    Sorry, if it's 4 days old and your wheel is is flexing when you brake, take it back to the shop. It makes no sense for that to happen.

  3. #3
    Senior Member Retro Grouch's Avatar
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    What makes you think that the whole front wheel tilts to the left?

    The way that most mechanical disc brakes work is with one moveable brake pad and one stationary pad. As you apply the brake the moveable pad warps the disc into the stationary pad. I'm wondering if watching this is affecting your perception.

  4. #4
    Senior Member Brian's Avatar
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    Good point, grouch. It may not be the wheel moving to the left, rather the disc moving to the right. But he is asleep now, as you should be.

  5. #5
    I'm switching to quads racersk66's Avatar
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    so disk are a pain in the ass if you dont know anything about them so go to your local shop

  6. #6
    I'm switching to quads racersk66's Avatar
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    Quote Originally Posted by Expatriate
    Sorry, if it's 4 days old and your wheel is is flexing when you brake, take it back to the shop. It makes no sense for that to happen.
    i tend to agree

  7. #7
    Senior Member Brian's Avatar
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    Quote Originally Posted by racersk66
    so disk are a pain in the ass if you dont know anything about them so go to your local shop
    They're still discs, not "Disk". I guess he'll see you at the shop.

  8. #8
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    FWIW I HAD hydro discs HFX-9's and swapped them out for XT's. THank heavens too.

  9. #9
    Senior Member Brian's Avatar
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    I could devote an entire thread to telling you guys what's wrong with custom 203mm titanium rotors, but I won't. XT discs are the flattest, most laterally true discs I have used. And it seems like they all squeak or squeal at one time or another. Finnicky bastids.

  10. #10
    The Red Lantern Rev.Chuck's Avatar
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    This might be silly but make sure the quick release is good and tight*. A brake disc really torques the wheel in the dropouts and if it is loose or even not real tight it can cock the wheel in the dropouts.
    If the movement you see is the rotor flexing over a bunch you will need a 2.5mm(I think might be 2.0) and a 5mm allen wrench. You loosen the small stop screw in the caliper body and then you can screw in the fixed pad to decrease clearance. Truly, the best thing is to go to the shop and get one of the guys to adjust it and show you how to do it. Hard to describe exactly all the things to check and do just typing.

    *Release and retighten to make sure the wheel is fully in the dropouts

  11. #11
    I drink your MILKSHAKE Raiyn's Avatar
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    Quote Originally Posted by racersk66
    so disk are a pain in the ass if you dont know anything about them
    Quote Originally Posted by Pot
    Hey Kettle! You're BLACK

  12. #12
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    Quote Originally Posted by playincard
    Sorry guys, as I'm sure you get plenty of first-time posters whining about disk brakes here. But my friendly neighbourhood bike shop is too far away to drive + drop off the cycle to for a tuning when a DIY jobber might cure all.

    Having purchased a Specialized Hardrock Comp Disc four days ago, equipped with Hayes MX-2 mechanical discs, I'm having some problems already (go figure) that I believe go beyond the lines stretching. The first and foremost is the rubbing that occurs b/w the disc and the pads when the (primarily) front wheel is spinning. When I wail the front brake hard, and this is the scary part, the whole front wheel kind of tilts to the left (the side of the wheel on which the disc is mounted). It's worrying stuff, mostly because I'm a disk newb. I've already readjusted the brake lines a couple of times due to stretching. Before going all out and making this more confusing than it has to be, any ideas?

    Thanks in advance!
    Sounds like your QR skewer might not be tightened. Check on that, then take a look at http://www.hayesdiscbrake.com/pdf/MX...EnglishWeb.pdf for directions to center the disc between the calipers. Lots of people here are bashing MX2s, but they seem to work quite well if properly adjusted.

  13. #13
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    Thanks you alls for the ideas.
    The wheel is definitely flexing; watching it from above the handlebars (and using them as a point of reference), the wheel - not the brake rotor - clearly tilts up to 5 degrees to the left when the front brake is heavily applied. It is still making some noise during braking, which leads me to believe it's all simply a bad install and not just an abnormally long wear-in period, and that I should take this thing back to Mark the Bum Mechanic for a checkup. Plus, the rotor is pretty much rubbing against the stationary caliper when spinning freely; according to Hayes manual, this isn't the way it should be aligned between the calipers.

    However, thanks for the link, krezirussian; I will try to center the rotor between the calipers nicely before raging back to the bike shop. I appreciate the detailed description from Rev.Chuck, but as you say... I'd be more comfortable having the shop guys show me around the brakes. Thanks again for the opinions and concern, wish me luck!

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