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Brakepad rant

Discussion in 'Bicycle Mechanics and Repairs' started by Yellow Fang, 24 Apr 2008.

  1. Yellow Fang

    Yellow Fang Guru

    Location:
    Reading
    I changed over from v-brakes to disks recently. I was persuaded they were better and overall less maintenance. But I am cheesed off with the back brake squealing, so I went to the bike shop to get some more pads. I looked at the brakes carefully and got some that appeared to be compliant. When I got home, I found they did not fit. So I take the pads back and buy some others on-line, taking care they were compatible with the type of disk I'm using. They don't fit neither, so I've wasted £12. Why do they do this? I feel like slinging out my discs and going back to v-brakes.;)
     
  2. Your rear brake is squealing because either the pad has become contaminated or the disc brake mounts on the frame haven't been faced properly. If they aren't contanimated replacing the pads won't silence your brakes.

    Merely touching the surface of the pad can spoil them enough to induce a wail which requires a resurfacing of the pad with a file. Getting lube on them will contaminate them so deeply that no amount of resurfacing will fix them.

    Few shops have the equipment to face the caliper mounts, but since it's something which should have been done at the factory it will be covered by your frame warranty.

    My first disc bike squealed like a stuck pig even with faced mounts and new pads. The solution was to coat the disc with mud, although I've read that Coca Cola works just as well, to accelerate the bedding-in period.

    As I once heard said to a customer bringing her new bike in to have the indexing tweaked; 'Dont worry love, it's just a bit of newness'.
     
  3. OP
    OP
    Yellow Fang

    Yellow Fang Guru

    Location:
    Reading
    I've just fitted some new pads. If it still squeals tomorrow, it's going in the canal.
     
  4. RedBike

    RedBike New Member

    Location:
    Beside the road
    Some discs squeal in the wet no matter what you do. However, most (when correctly setup) are silent when dry.

    Sounds like you just need to align them correctly then bed them in.
     
  5. Doesn't sound worth the bother to me. Go back to rim brakes.
     
  6. Tynan

    Tynan Veteran

    Location:
    e4
    liked the disc on my short lived cannondale a lot but the front brake used to get very noisy, apparently dirt used to get onto the pad and stay there, apparently spinning the wheel backwards and braking removed it

    sadly the cannondale was so shortlived I never got to try that myself
     
  7. OP
    OP
    Yellow Fang

    Yellow Fang Guru

    Location:
    Reading
    Well it still squeals despite the new pads. I can feel the vibrations through the saddle and brake lever. It's not right. What is this facing process of which you speak?
     
  8. The mount onto which the calipers do bolt need to be in precise alignment with the disc/wheel/center line of the bike. If it aint straight the pads dont contact the disc straight, one pad has its trailing edge contacting first (toed-in) the other has its leading edge contacting first (toed-out) Tis the latter causing the cacophony.

    A disc mount facing tool resurfaces the inside surface of the disc mount.
     
  9. OP
    OP
    Yellow Fang

    Yellow Fang Guru

    Location:
    Reading
    Well, I took it back to the bike shop today. The shopkeeper still reckons it's contamination, so he's going to clean the disk with meths. It looks like I probably wasted another £9 on the pads because they are probably blued. However, at least I probably didn't waste the previous £12 because he fitted different disks front and back. He put Hope M4 on the front and Hope mini-disks on the back. I think he has some arrangement with Hope, because he phoned up their help-desk to ask their advice. He doesn't seem to reckon it's an alignment problem.
     
  10. OP
    OP
    Yellow Fang

    Yellow Fang Guru

    Location:
    Reading
    Correct.

    The bikeshop owner says he's going to buy a facing tool. He's eliminated other possibilities. He said he didn't really want to buy one (as it costs £200), but that he knew he'd have to at some point, which I think is pretty decent of him. He said that, speaking to the guys at Hope, steel frames seem to be a bit worse than aluminium frames in this regard, and that Hope had reported a previous problems with On-One frames. When he gets the tool, he'll ring me back, so soon I will be free of this back brake squealing hell.
     
  11. threefingerjoe

    threefingerjoe Über Member

    Location:
    St. Louis, MO, USA
    is this on a mountain bike? I can understand the advantage of disk brakes on mountain bikes, as it gets the brakes further away from the mud and water, but I'm beginning to see more disk brakes on bikes that will NEVER leave the tarmac. Is this just a fad? What is the advantage? I use the Kool-Stop salmon pads on my rim brakes and they have more stopping power than I'll ever need, and last plenty long enough, and seem to be trouble-free.
    Help me understand this. Am I missing something by not having disk brakes?
     
  12. OP
    OP
    Yellow Fang

    Yellow Fang Guru

    Location:
    Reading
    It is a mountain bike but I use it mostly for commuting now. The shopkeeper persuaded me that long term they were less maintenance because they stopped the rims wearing out. He said it was difficult getting 26" rims with braking surfaces these days. I'm not sure how true that is. I thought v-brakes were good. Disk brakes certainly look good.
     
  13. RedBike

    RedBike New Member

    Location:
    Beside the road
    Meths wont clean the discs. Meths will leave a residue.

    As for not having a facing tool. How is he building up new bikes / fitting disc brakes without it? I take it he just screwing them on an praying they line up correctly.

    All in all it sounds like it's time to start visiting a different shop!
     
  14. RedBike

    RedBike New Member

    Location:
    Beside the road
    There's no trouble getting 26" wheels with braking surfaces? Although disc brakes do come into their own in muddy wet conditions there really isn't any need for them on a tarmac commute.

    Disc brakes are often fitted more out of fashion than requirement.
     
  15. col

    col Veteran

    I too was always puzzled by this,there is only so much stopping power needed,especialy on the rear?Thats if the stopping power is improved that much,but it still wouldnt convince me to use them,the ones i have could put me over the handlebars if i wanted them too,so feel no need for disks.