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  1. #1
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    One brake damper always touches wheel?...

    Hi all,

    I'm relatively new to biking and I'm new to the forum. I bought a Trek 7.3 FX today, and after I got it home, I noticed that one of the front brake dampers (not sure if that is what it is called, but I've attached pics to show exactly what I'm referring to) is permanently touching the front wheel. The pics show what I'm talking about, although from the pic you cannot necessarily tell that the damper is actually touching the wheel -- it is. The second pic is a zoomed in version of the first pic. Thus, the front wheel doesn't spin as well as it should because there is perpetually a small amount of resistance from that brake damper.

    My two questions are... 1) This should not be happening, right? 2) Is it something I can fix myself, or do I need to take it back to the place I bought it and have them fix it?

    Thanks!
    Attached Images Attached Images

  2. #2
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    that is an improperly positioned brake shoe--- undue it with a allen key squeeeze the brake and tighten to position--- someone will mention toe-in or toe-out to you but I like my pads to be square
    with the rim--- these a knuckled mtb pads-- adjustable and fixable and replaceable--- cheerie o

  3. #3
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    That can be adjusted out. Since the bike is brand new, take it back to the bike shop for the correction.

  4. #4
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    You could take it back but this is a super simple adjustment and you may as well start learning about your bike right now.

    First off it's nice that the shop set up the brakes with some toe in but I think they went a little overboard. That's a LOT of toe in.

    Second there is a couple of return tension screws on the base of the arms right near the pivots that you can use to balance the return tension so the two arms swing equally away from the rim.

    Bookmark this page RIGHT NOW. It's your gateway to finding a lot of info that many folks here have reported to be very helpful.

    http://www.parktool.com/repair/

    Move your mouse over the brakes on the bike for the link to the brake repair list. From that list pick the second one for "Linear pull brake service". It'll lead you by the hand through everything you need to know as well as how to tune out your present predicament.

    It's actually an extremely simple adjustment and it's a good start to learning this stuff for yourself for later when there's no warranty.
    Model airplanes are cool too!.....

  5. #5
    Senior Member onbike 1939's Avatar
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    I think that before touching the brakes I'd check that the wheel is centred, as it's difficult to tell this by the photo.

  6. #6
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    Quote Originally Posted by onbike 1939 View Post
    I think that before touching the brakes I'd check that the wheel is centred, as it's difficult to tell this by the photo.
    Excuse my ignorance, but how exactly do I do that? I removed the wheel and re-attached it, doing my best to make sure it was as even as possible... is that what you are talking about? Thanks.

  7. #7
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    Quote Originally Posted by chrikenn View Post
    Excuse my ignorance, but how exactly do I do that? I removed the wheel and re-attached it, doing my best to make sure it was as even as possible... is that what you are talking about? Thanks.
    When I have one side's brake pad rubbing it is because the brake has been bumped in moving the bike about. So I just take hold of the brake with my hand and move it little so neither side is rubbing. Note nothing bad is going to happen if it moves from hand pressure. And if this doesn't work, take it back to the lbs and watch the way the wrench corrects the prob.

    Good luck

  8. #8
    Senior Member BCRider's Avatar
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    Making sure it's seated completely in the dropouts is one thing but it's sort of assumed that you'll do that. Not a good assumption for a newbie to wrenching mind you. But you got that part already so good on ya'.

    But what he's reffering to is the "dish" of the wheel which is set by the spoke tensions from side to side that hold the rim. The "dish" is the measure of where the spokes are allowing the rim to sit between the stays (the sets of tubes from the axle forward to the main triangle that the wheel sits in) or fork legs. When the dish is right the rim will sit evenly between the frame stays. You can check this by using a ruler or something fancier to measure the distances from the brake tracks on the rim to the stay tube and see that they match. If the measurements do not match to within 1/16 inch then the wheel should be trued to set the dish and thus center the rim.

    Another website that'll keep you busy learning all you ever wanted to know and a lot you never dreamt about is www.sheldonbrown.com . Between the Park site and the late great Sheldon Brown there's precious little left that needs saying. If you're keen on all this stuff, which by your posting here I gather you are, then it's well worth sitting down with a cup of something hot or cold and browsing through of Sheldon's website. There's a lot to absorb but even a casual first time through will greatly entertain, enlighten and enable you. And you'll remember where to find stuff later when you need it.

    We're still here to help out with any confusion but once you see these two websites you'll understand why so many answers say "...go look at Park/Sheldon's....".
    Model airplanes are cool too!.....

  9. #9
    Senior Member BCRider's Avatar
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    Quote Originally Posted by jim6b View Post
    When I have one side's brake pad rubbing it is because the brake has been bumped in moving the bike about. So I just take hold of the brake with my hand and move it little so neither side is rubbing......
    It sounds like you have caliper brakes. Tweaking them like that works fine for caliper brakes where there is one screw above the tire that holds the whole assembly on. But this guy has V brakes so if you do that they will just spring back to being misadjusted. Different systems, different solutions.
    Model airplanes are cool too!.....

  10. #10
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    Thanks to everybody for all the great advice. Those websites are great. I could spend all day looking at them.

    I'm going to try to fix this myself by readjusting the brake pad, but if I have any trouble I'll just take it back to the store and ask them to let me watch while they fix it. Seemed like a pretty friendly group of people so my guess would be they won't mind. Plus, their repair area is right out in the open, so I'm not sure they could make me leave even if they wanted to =P

  11. #11
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    Good news. I fixed the toe-in problem and the wheels appear to be spinning as they should be now. In the process though, I came up with another question. Although now all of the brake pads are completely clear of the wheel unless I pull the brake lever, some of the brakes pads are closer to the wheel than others. My guess is that it is supposed to be symmetrical? Well, I could not figure out how to increase the amount of space between the brake pad and the wheel. I've attached a pic showing which screw I loosened to fix the toe problem, but loosening that same screw did not seem to give me the ability to move the brake pad a little further away from the wheel. Any suggestions on how to do that?

    Thanks!

    P.S. And yes, the bike is still resting upside down like it was in the first two pics.
    Attached Images Attached Images
    Last edited by chrikenn; 09-06-08 at 11:32 AM.

  12. #12
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    See the other smaller silver screw closer to the mount? That's the one that adjusts the amount of return spring tension each arm has. Adjusting that to equalize the arm travel and thus the pad spacing is outlined down in the lower part of the Park Tools info on V or linear brakes.

    The gap is set by matching the tensions so that both arms retract the same amount. When you adjust it use 1/4 turn in on the tighter arm or 1/4 turn out on the further out arm and then pump the brake lever a couple of times to let the arms find their happy spot. If it's still out then do it again. But small adjustments with a couple of brake activations is the way to go.

    When I do mine I don't measure the pad to rim gap. I just watch the tops of the arms. If they look like they move the same amount then that's close enough.
    Model airplanes are cool too!.....

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