Adjusting v-brakes

Discussion in 'UK and Europe' started by Nick Williamson, Jun 18, 2003.

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  1. Hi all,

    I have Shimano Acera v-brakes and I have a lot of free play on the back brake lever. The brake shoes
    are nice and close to the rims but I can pull the brake lever almost all the way with little or no
    effect. This is a problem that's got worse over the past few weeks and I don't know what to adjust:
    is it a case of pulling more cable through the V-brake assembly and re-tightening the screw, or
    would the adjustment be made to the brake lever itself?

    Sorry for asking such a newbie question! I've searched the uk.rec.cycling archives and the web
    without success...

    TIA Nick
     
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  2. Peter Clinch

    Peter Clinch Guest

    Nick Williamson wrote:

    > This is a problem that's got worse over the past few weeks and I don't know what to adjust: is it
    > a case of pulling more cable through the V-brake assembly and re-tightening the screw, or would
    > the adjustment be made to the brake lever itself?

    Most Vs can be adjusted by tensioning the cable at the brake lever assembly, by screwing the
    adjuster out (i.e., you lengthen the cable run path by the same amount as the block wear).
    Ultimately, however, you run out of adjustment this way, at which point pulling a little more
    through where the cable is clamped to the brake assembly may well be called for. If you do this,
    make a point of resetting the adjustment screw at the lever first, so giving you more to play with
    back at that end in future.

    As I've found out the hard way (i.e., by getting it wrong) there can be a bit more to V adjustment
    than just clearance. The pad mounts can be independently angled thanks to the ball/cup
    thingummies[1] on the spacers, and the spacers themselves usually have a choice of thick and thin
    for each side of the mounting slot so you can choose the best according to the rim/mount clearance.
    Make sure that when the brake is pulled tight the pads are coming up pretty well square (relative to
    the plane of the worn pad surface) against the rim, and if they're not then fiddle with the
    aforementioned until they do. As I found out, this can make the difference between brakes that work
    and brakes that bottom out against the handlebars.

    Some Vs have further adjustment possibilities given by independent screws that change the relative
    clearance of L and R pads (a wee grub screw on the mech by the pad mount, one each side). You only
    need to worry about this if one side is closer in than the other.

    > Sorry for asking such a newbie question!

    There are lots of people with V brakes who have only a dim awareness that they even *can* be
    adjusted, so no need to apologise!

    Pete.

    [1] a technical term, obviously...
    --
    Peter Clinch University of Dundee Tel 44 1382 660111 ext. 33637 Medical Physics, Ninewells Hospital
    Fax 44 1382 640177 Dundee DD1 9SY Scotland UK net [email protected]
    http://www.dundee.ac.uk/~pjclinch/
     
  3. Peter B

    Peter B Guest

    "Peter Clinch" <[email protected]> wrote in message news:[email protected]...
    > As I've found out the hard way (i.e., by getting it wrong) there can be a bit more to V adjustment
    > than just clearance. The pad mounts can be independently angled thanks to the ball/cup
    > thingummies[1] on the spacers, and the spacers themselves usually have a choice of thick and thin
    > for each side of the mounting slot so you can choose the best according to the rim/mount
    > clearance.

    I find an easy way to set new pads is to unhook the cable and springs, the arms are now free. With
    the new pads fitted but left loose I then press the arm so the pad engages the rim, you can then
    tweak the pad so it's face is presented flat to the rim, the ball & socket thingie allows the pad to
    articulate into position. Place a bit of thin card under the trailing edge of the pad between it and
    the rim before tightening, this helps prevent brake squeal.

    http://www.parktool.com/repair_help/howfix_linearbrakes.shtml for more help.

    Pete
     
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