Weak AVID disc breaks

SJLcp
SJLcp Posts: 239
edited June 2007 in Workshop
My cannondale crosser has avid disc brakes which are a couple of years old - they don't seem very powerful any more so I replace the discs which were half worn but with little improvement - so I roughed up the shiny discs (they looked a bit glazed) with a dremel which made things a little better but still not great - can't lock the rear wheel up.

Any ideas please?

Comments

  • denzil023
    denzil023 Posts: 27
    Have you tried bleeding the brakes or replacing the pads?
  • donald_ii
    donald_ii Posts: 98
    <blockquote id="quote"><font size="1" face="Verdana, Arial, Helvetica" id="quote">quote:<hr height="1" noshade id="quote"><i>Originally posted by denzil023</i>

    Have you tried bleeding the brakes
    <hr height="1" noshade id="quote"></blockquote id="quote"></font id="quote">

    Not an option with mechanical disks [:D] !
    However the cables could be compressing - especially if you are using standard road cables through in-line levers.
    On my cross bike,I had to use avid flak-jacket cables, as the supplied campag road cables compressed about 1cm when pumping hard on the levers.
  • denzil023
    denzil023 Posts: 27
    LOL [:I] I thought that about an hour after I posted. Not to worry. New cables sounds like the next plan of action!
  • Unknown
    Unknown
    If the cables haven't been replaced since new, thats what i would be doing first.
    you might have sticky pistons too

    Mleh Mleh Mleh
  • SJLcp
    SJLcp Posts: 239
    Hmm - hadn't thought of the cables - and it does have in line levers. Will give that a go first - many thanks
  • Unknown
    Unknown
    definotly cables and pads...........

    --

    Insert stupid, possibly baby elephant realated, comment here......
  • Down the Road
    Down the Road Posts: 949
    Why not take it to a qualified mechanic and get him to set them up properly.
    Racing is life - everything else is just waiting
  • Unknown
    Unknown
    Down the road

    Why do you always suggest that people take things to a shop?
    its not helpful to anyone. ALL bike maintenance can be done by a budding home mechanic, with a little advice and the aid of on-line guides.
    Many people come on this forum and ask advice, and your advice is always to take it to a shop.
    The only thing i need to visit a shop to have done is to get facing done as i don't have the expensive tools.
    but changing cables is within the grasp of most people and could attempted by anyone.

    Can you change cables Down the road?

    Mleh Mleh Mleh
  • hazeii
    hazeii Posts: 233
    Seems like sound advice to me; an Avid disk brake that won't even lock a real wheel must have something seriously wrong, and if it's not obvious to the OP then I too would recommend taking the bike to a shop.

    Seems unlikely to me it's a cable problem anyway (barring exceptional neglect :) ). Could be a mismatched setup that worked at first but has now degraded (e.g. MTB Avid with road lever, or a very tired set of pads). Will be interested to hear the outcome though!
  • Jonathan Mcp
    Jonathan Mcp Posts: 2,472
    Cable discs are extremely sensitive to cable problems, a rough cable run that wouldn't be an issue on a V or caliper bike can rob a lot of "power", as can cheap cables. When I used cable discs I used Gore cables to prevent any problems worked well.

    Might pay to check the caliper set up, that it hasn't moved and is hitting the disc "square", and that the pad adjusters are used to make sure the pads have minimal clearance between them & the disc. This doesn't need an LBS mechanic, BTW, as instructions for the Avid systems are readily available on the internet. It might just be a "fettling" that is required. I can't recall if the avid caliper can be dismantled & regreased internally, as that would be a possible, but Avid cable discs have an extremely good reputation, I never needed to do this (and mine were purchased 2nd hand) & I've never heard of anyone else having to do tbis either.

    Discs themselves are a straightforward system really, disc, pad, and a means of actuating the brake. A loss of power has to come from within these parts.

    No chance that the pads are contamintaed with anything is there? And if you fit new ones, don't forget they need bedding in - a nice muddy ride, lots of heavy braking 10-20 times usually does the job.

    <font size="1">It isn't growing up that stops us playing, it is stopping playing that makes us grow up.

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