Disc Rub Caused by Chain Stay

parkinpants
parkinpants Posts: 53
edited July 2014 in MTB workshop & tech
Hi,

I have had a problem with disc rub ever since I bought my bike (many years ago). I know a little bit of rub is okay but this is quite bad. I've been methodically trying to figure out what the problem is so here's where I'm at:

1. Wheel is true and centred
2. Rotor is true
3. Cailpers have been calibrated using the lossen/squeeze+pump/tighten technique
4. Replaced the calipers

Even after that, still getting a lot of disc brake rub. Then the penny dropped that it must be something to do with the chain stay. This dawned on me because:

1. I always have trouble adjusting it whenever I take the wheel off (punctures). Adjusting the tension always makes a difference. Usually the tighter I fasten the wheel (cup and cone hub) the worse the disc rub

2. I put panniers on my bike once which made the disc rub really bad. When I took it off it was much better - the pannier were putting a lot of pressure on the frame, pushing the chain stays towards each other.

To test it out, I took off the wheel and just pulled the chain stays away from each other. Voila, the disc rub was much better. Now, I'm not convinced it will stay like this because I'm sure I've started out on a ride with minimal rub, but by the end of it it's bad.

Is this common problem? Anyone heard of it before? What's the solution? Could I put a spacer on the hub axle to widen it out? Or should I be looking at meddling with the nuts/spacers where the caliper meets the frame/mounting bracket?

thanks

Comments

  • mcnultycop
    mcnultycop Posts: 2,143
    It's just when you take the wheel out, it never goes back into exactly the same position.

    You may be overanalysing it.
    Nerve AM 7.0
    Scandal
    Felt Roadie
  • parkinpants
    parkinpants Posts: 53
    Yeah I have that with the front wheel, but simply re-aligning the calipers or adjusting the tension at the quick release fixes it easily enough. With the back wheel it's a different story.
  • The Rookie
    The Rookie Posts: 27,812
    When you tighten up the wheel it will pull the dropouts to the OLD so that will fix the dropouts where they are, sounds to me like you have a problem fitting the wheel consistently.
    Currently riding a Whyte T130C, X0 drivetrain, Magura Trail brakes converted to mixed wheel size (homebuilt wheels) with 140mm Fox 34 Rhythm and RP23 suspension. 12.2Kg.

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