Half an Inch Front Wheel Movement when front brake is applied- Mtbr.com
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  1. #1
    AndesJack
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    Half an Inch Front Wheel Movement when front brake is applied

    I need advice as to the source of this problem. I have a set of Avid 5's, more specifically the front 185mm rotor is on a Marzocchi 55ATA (New bike and parts 4 rides old). When stationary and I apply the brake the disc locks (all good) but then when I move the bike forward while applying the front brake, the wheel turns about half an inch. This can't be OK. Any advice will be greatly appreciated.

  2. #2
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    Reputation: Dremer03's Avatar
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    Avid 5's? Do you mean Avid BB5 Brakes? Elixer 5? Code 5?

    You should be able to lock the front tire at will, at least I can with my BB7 brakes. You could simply have something on your rotors like grease or oil. I am not a brake expert by any means, but I would check what I just suggested.
    Big Foot Blue KHS XC704r

  3. #3
    mtbr member
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    Pads can move in the caliper giving a "loose sensation". Apply the brake , rock it back and forth while a helper watches the caliper area .

  4. #4
    ...idios...
    Reputation: SteveUK's Avatar
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    Check all bolts (mounts/caliper/rotor). Check fork axle (QR20?). Is the axle o-ring greased?

    Having a helper is indeed very useful at times like this. Have somebody recreate the issue while you grab caliper/fork/hub/whatever to identify the source of the play.

    What use is a philosopher who doesn't hurt anybody's feelings? -
    Diogenes


  5. #5
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    Reputation: stevereeneo's Avatar
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    As was stated you need to find EXACTLY what's moving when you lock up the front brake... though if the disc locks as you said, I would look at the following (not in any particular order):

    Loose caliper bolts (in the fork adapter/post mounts) as (SteveUK mentioned)
    Loose headset (not uncommon on a new bike after a few rides!)
    Play in the fork between the lowers and the stanchions (not likely on a new bike)
    Play in the stem/steerer/h-bar interface
    Loose hub bearings (unlikely on a new wheel but possible) or Hub/fork connection (as was mentioned)
    Loose rotor bolts
    Depending on the brakes the idea of the pads moving in the caliper is also a possibility as was mentioned above. Sometimes folks can knock a pad out of its seated position in the caliper while putting a wheel on (or taking it off).

    Get back to us and let us know what you found.

    S
    "You know how they make aluminum bike frames? They take steel and suck out all the soul..."

  6. #6
    AndesJack
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    Thanks for the advice. Let me go check it out tonight and revert back.

  7. #7
    ...idios...
    Reputation: SteveUK's Avatar
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    Quote Originally Posted by Jacques Pienaar
    Let me go check it out tonight and revert back.
    Revert back to what?

    What use is a philosopher who doesn't hurt anybody's feelings? -
    Diogenes


  8. #8
    AndesJack
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    Forgot to mention the brakes are Avid Juicy 5's. I think the issue might be the obvious, rotor bolts. The hub fork connection (XT 20mm through axle hub) might be the other but let me stop speculating and get back to you all with the real source of the matter. Thanks again.

  9. #9
    AndesJack
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    revert back, get back to you.

  10. #10
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    Reputation: SteveUK's Avatar
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    Quote Originally Posted by Jacques Pienaar
    revert back, get back to you.
    I think you mean report back. Revert means something rather different.

    I ask about the axle because the Marzocchi QR20s have a habit of working loose if the o-ring on the handle-end of the axle is not kept greased.

    What use is a philosopher who doesn't hurt anybody's feelings? -
    Diogenes


  11. #11
    AndesJack
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    I found that the disk needs to be fastened. I attach a picture of the disc and lock mechanism, much different to the more alankey type I'm use to but I suppose a new tool from the shop is what I'll have to buy. Can I follow the torque setting provided on the disc itself, not too sure about these?
    Attached Thumbnails Attached Thumbnails Half an Inch Front Wheel Movement when front brake is applied-img_0708.jpg  


  12. #12
    AndesJack
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    Trying that pic again
    Attached Thumbnails Attached Thumbnails Half an Inch Front Wheel Movement when front brake is applied-img_0708.jpg  


  13. #13
    Meh.
    Reputation: XSL_WiLL's Avatar
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    You have a centerlock hub, It's a lockring on top of an adapter allowing you to use 6-bolt rotors. The lockring needs to be tightened. Looks like this particular one may use a BB tool to tighten.

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