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Strange problem suddenly appeared with my brakes

drwaedrwae Posts: 223
edited March 2017 in Workshop
This just started a few weeks ago, previously my brakes were fine (Ultegra 6800). I think it has happened on the front but lately I've only been noticing it significantly on the rear.
I will go for a ride (even a short 10 minutes to the gym) and when I get off the bike I notice the brake pads aren't an equal distance from the braking surface any more. One will be really close and the other will be really far away. Sometimes I have even got my bike out the rack to use it and found one side is rubbing.
It seems to be resolved by opening the quick release and putting it back down again, that puts the pads back to an equal distance.
I have also tried adjusting the distance using the little allen bolt and I still get the problem.

It's probably something really simple but I'm no mechanic! :)

Posts

  • fat daddyfat daddy Posts: 2,605
    mine do this when they need a clean ..... might not be your issue, but if It was my bike and used in all weathers, it would be a clean and lube the pivots and cable.
  • drwaedrwae Posts: 223
    fat daddy wrote:
    mine do this when they need a clean ..... might not be your issue, but if It was my bike and used in all weathers, it would be a clean and lube the pivots and cable.
    I've already tried to lubricate the pivots and I clean the bike every time it gets really dirty but I haven't really paid much attention to the cables, will see about lubricating the brake cable and maybe flushing out the rear housing with some gt85, cheers
  • jermasjermas Posts: 484
    Check the calipers are mounted tight enough (8Nm-10Nm) to the frame/forks. If they're loose they can rotate on their central pivot.
  • drwaedrwae Posts: 223
    jermas wrote:
    Check the calipers are mounted tight enough (8Nm-10Nm) to the frame/forks. If they're loose they can rotate on their central pivot.
    I'd have to get a torque wrench to do that one... :)
  • fenixfenix Posts: 5,437
    Just check with an allen key then - sounds like they aren't tight enough - thats the only way they can move.
  • drwaedrwae Posts: 223
    Fenix wrote:
    Just check with an allen key then - sounds like they aren't tight enough - thats the only way they can move.
    I did already check that and they're very tight. If they were loose I'm not sure why opening and putting back the QR would fix it? I'm thinking its cables now like fat daddy suggested otherwise not sure why the QR would do anything
  • jgsijgsi Posts: 5,029
    You are aware of the tiny magical centering allen bolt?.. it is magic

    I'd just make sure the back wheel is bang on fitted in the dropouts if you've been bashing it about in bike racks though.
  • cooldadcooldad Posts: 32,601
    Discs would solve your problem.
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  • LeeDaLeeDa Posts: 82
    Check your cable outers aren't too short or long resulting in the brake calliper being pushed off centre.
  • BobbinogsBobbinogs Posts: 4,841
    edited March 2017
    My vote would be for cable Friction.

    I suspect that there is some friction stopping the cable releasing properly and this can result in a brake offset because of the way dual pivots work. To prove this, after a ride where the blocks have gone awry, undo the clamping bolt on the brakes and see if the blocks move back to where they should be (albeit probably a way off the rims). To resolve, just the standard thing of using some oil based lube (like 3in1) on the brake cable, paying particular attention to the small outer cable at the rear of the bike. This is exposed to the elements and tends to get a little sticky over time.
  • drwaedrwae Posts: 223
    I've just given the housing at the rear a clean so I'll have to see if that solves it. I don't think it can be related to the housing length as the problem spontaneously appeared without me changing the housing/cables.
  • drwaedrwae Posts: 223
    cooldad wrote:
    Discs would solve your problem.
    If you pay for the new frameset I'll pay for the disks, deal? :)
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