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Thread: flummoxed

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    Ride More seedsbelize's Avatar
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    flummoxed

    Hi All,
    I have a set of Shimano 600 (BR6203) caliper brakes I'm having difficulty with. The front is fine. The rear, however, doesn't have enough reach on the non-drive side, though it is fine on the drive side. I've tried both 700C and 27"rims with the same result. The brake shoe maybe won't ride on the tire bead, but it seems like it will. I have also tried different pads. I'm guessing it's a set-up issue, but have been unable to figure it out.
    This is the best I can do. The pad hits the other side midway across the track. 39-49cm reach--seems like it should be enough. As always, Thanks in advance.
    600ex 001.jpg

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    Ride More seedsbelize's Avatar
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    PS These are single pivot brakes.

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    Is the caliper centered over the rim? If it's off-set to one side, one pad will ride higher. Single pivots can be a bit tricky to center and seem to get knocked off-kilter fairly easily.

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    interesting problem.

    as regards previous advice, i'm assuming the calipers are reasonably centered. and because the pic doesn't show it, we can't see the "good" side, so have nothing to compare to.

    i tried misaligning my 600 front caliper as much as possible, even going to the trouble to open the qr, to drop one brake pad and couldn't see much difference.

    of course, whether or not any caliper brake has a long enough reach is a consequence of a number of factors, but what's interesting is that the problem doesn't occur on the non-drive side.

    BTW, it looks as though the quick release is in the released position, not that it makes any difference on the 600's on my bike... so i'm wondering if the non-drive side arm is bent. they are angled forward, but they are designed that way.

    one thing someone mentioned the other day comes to mind, but really doesn't address the asymmetrical nature of your problem. it mentioned that any additional washers on the front side of the fork will unnecessarily shorten the reach.

    but to address the asymmetry issue, i think i would take the time to disassemble the rear brake and swap out just the arms to the front brake and see where that led me.

    but before you go to that trouble, you may want to swap out those pads, it's just possible that they are not symmetrical as regards the mounting bolt, either intentionally or as a result of a flaw. they may even be directional...

    and if you have to bite the bullet and address the symptom rather than the cause, i saw some brake pads that had offset attachment bolts that would give just a little more reach. but i'm pretty sure you'll find the problem and then the fix should be obvious. good luck.
    Last edited by hueyhoolihan; 04-22-14 at 06:45 PM.

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    Forget about the brake for a moment and look at the wheel and frame. If the wheel is centered under the brake hole, the reach will be equal on both sides.

    The fact that it isn't means the rim is off center.

    That said, if it's a question of 1mm or so, use a rat tail file to lengthen the slot if necessary.
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    Quote Originally Posted by FBinNY View Post
    Forget about the brake for a moment and look at the wheel and frame. If the wheel is centered under the brake hole, the reach will be equal on both sides.

    The fact that it isn't means the rim is off center.

    That said, if it's a question of 1mm or so, use a rat tail file to lengthen the slot if necessary.
    yes, it would be nice to have a front view, *hint*.

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    Quote Originally Posted by hueyhoolihan View Post
    yes, it would be nice to have a front view, *hint*.
    I am shocked that the pic we have came out as well as it did. I was holding the flashlight in my good hand and snapping the photo in my off hand. So it has nothing to do with the way the arms are put together then? I'll try try again.

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    After everything else has been ruled out, Take the brake pad off. Grab the caliper arm with some Channel-locks and give it a little bend outward so the pad points down a bit more...... Ok, I'm kidding .... Sort of.
    Bikes: Old steel race bikes, old Cannondale race bikes, less old Cannondale race bike, crappy old mtn bike

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    Quote Originally Posted by seedsbelize View Post
    I am shocked that the pic we have came out as well as it did. I was holding the flashlight in my good hand and snapping the photo in my off hand. So it has nothing to do with the way the arms are put together then? I'll try try again.
    you are right. i don't suspect that they are put together wrong, but now that you mention it, should i have reason to? for the most part, when i used to put them together wrong, which i did occasionally, they wouldn't work at all.

    BTW, how much of a discrepancy is there between the right and left sides? i ask because there is such a thing as a manufacturing tolerance. if it's a millimeter or two, well, i might expect that. if so, a little filing could be in order.

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    Quote Originally Posted by seedsbelize View Post
    I am shocked that the pic we have came out as well as it did. I was holding the flashlight in my good hand and snapping the photo in my off hand. So it has nothing to do with the way the arms are put together then? I'll try try again.
    If it's single pivot, there's not much you can do wrong. Each arm has the slot for the brake shoe at one end, and one round hole at the other. The distance between them is fixed, or as we say "cut in stone".
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  11. #11
    Ride More seedsbelize's Avatar
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    Thanks all,
    I rebuilt the hub, and moved the spacers around; then re-dished it. And Voilá!!
    Thanks again!

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    bike whisperer Kimmo's Avatar
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    Quote Originally Posted by HillRider View Post
    Is the caliper centered over the rim? If it's off-set to one side, one pad will ride higher. Single pivots can be a bit tricky to center and seem to get knocked off-kilter fairly easily.
    Not on a single pivot... unless maybe it's the rim that isn't centered in the frame.

    ...Now that I finish reading the thread, well there you go.

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