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Proper dual-pivot, long reach set-up

Discussion in 'Bicycle Mechanics and Repairs' started by goo_mason, 26 Jun 2008.

  1. goo_mason

    goo_mason Champion barbed-wire hurdler

    Location:
    Leith, Edinburgh
    OK.

    The front brakes on my SCR2 seem to be set up wrongly - the right-hand pad has worn half-away whereas the left-hand pad still looks as big as the day the bike arrived. Obviously, the set-up needs tweaked a bit.

    Can anyone point me to a decent site that'll tell me how ? Park Tools' site doesn't really cover it.

    I'm also looking for info on the lube points (if any) for the pivots - I got nothing with the bike so I've no idea !

    Cheers !
     
  2. ColinJ

    ColinJ Slow Hill Climber/Station lift avoider!

    I don't know about a website, but I'll tell you how I do it...

    (This method assumes that your wheels are properly 'true', otherwise you could be working against part of the rim that happens to be too far one way or the other)

    I'd suggest that you replace the worn pad before going any further. I tried getting the last bit of wear out of an old set of pads once and ended up destroying the wheel rim - a false economy. If you have to brake hard you have no choice even if you have no brake pad material left, - better a damaged wheel than a damaged head!



    Okay - stand next to the bike and apply the brakes slowly, watching when they contact the rim. From what you wrote, it sounds as though the righthand brake pad is contacting the rim way before the left one does. In this case you will observe that the brake is pushing the rim over to the left. What you want to achieve is that both pads engage the rim at the same time so the rim doesn't move laterally no matter how hard you apply the brakes. You could use an allen key to loosen the brake assembly, then recentre it. I find that I can take a firm grip on the assembly and pull it over slightly in the desired direction without loosening the bolt. I suppose it depends on how tight it is and how strong your fingers are. If you loosened the retaining bolt - make sure that you tighten it back up!

    While I'm doing this job, I usually make sure that the brake pads are adjusted properly so that there is no chance of them either contacting the tyre or slipping off the edge of the rim towards the spokes. I also check my tyres for wear, cuts or embedded debris.

    Hope that helps ;)?
     
  3. Chris James

    Chris James Über Member

    Location:
    Huddersfield
    My Tektro Shimano clones have a little 1.5mm allen key headed grub screw that centres the brakes.

    But after I lost my 1.5mm allen key (!) I just do it the same way as above.

    You might want to check that both arms actually pivot in towards your rim when the brake lever is depresed. (I have no idea why they wouldn't but if they don't then centring won't help matters)
     
  4. goo_mason

    goo_mason Champion barbed-wire hurdler

    Location:
    Leith, Edinburgh
    Thanks Colin.

    The whole brake assembly on the rear wheel moves left and right if I push it very lightly with my hand, which I think may be a problem !! I thought they were meant to be loose like that - therein lies my ignorance on these types of brakes !! (My first bike had disc brakes so rim brakes are compoetely new to me). I'll need to tighten it up.

    I've never wobbled the front brake assembly with my hand, so you might be spot on with them being off-centre and probably tightened up that way. I'll get the bike up on the stand tonight to check things over.

    Probably just another case of cack-handed Halfords assembly as I got the bike ordered in via them on Bike2Work. (They set the brakes up with the quick-release open, so closing the quick-release meant that the brakes locked tight against the wheel - that much I knew was wrong and I adjusted accordingly when I first brought the bike home!)
     
  5. ColinJ

    ColinJ Slow Hill Climber/Station lift avoider!

    Yikes - I'd say so; it sounds like your brakes are about to fall off ;)!