New to MTB - quick disc brake/gears question

daverey
daverey Posts: 49
edited April 2009 in MTB beginners
Morning All

I'm brand new to MTB and at the weekend picked up a GT Avalance 3.0 Disc 09 for me, and a Specialized Myka HT Sport Disc 09 for the missus. Incidentally, both bikes appear to be tremendous for the money and for what we need, and we even managed a very short, but gruelling, off-road loop in the peak district yesterday on them.

Anyway....

Both bikes come with presumably bog-standard mechanical disc brakes. Since we've had the bikes home and practiced with removing and putting the quick-release wheels on, I've noticed that on both sets of front and back wheels, when you spin the wheel there is a very slight noise which I'm sure is the brake pad rubbing slightly. If this is the case it's hardly slowing the wheels from spinning, but there is definitely contact being made somewhere.

My question - is this normal? The guy at Evans' where we bought them said it will be fine, but I just thought I'd check to make sure that other people with discs experience the same thing?

Also, another quick question - this time on gears. On the missus' bike, when she is in the very lowest (ie least resistance) gears (1 & 2 on the easier chain-ring) - there is a quiet tapping noise as she is pedalling. When she moves up the gears this noise disappears, but then comes back again when she goes back down. Again, is this "normal", or is it something that could lead to further problems.

Ta in advance
Dave

Comments

  • Daz555
    Daz555 Posts: 3,976
    I tiny bit of disc rub is not uncommon before the brakes have bedded in. However, it is worth checking the wheels are properly into the dropouts and on straight. Also check that the discs do not have a wobble (warp).

    If the rubbing persists then you might need to look at realigning the caliper in order to centre it properly on the disc.
    You only need two tools: WD40 and Duck Tape.
    If it doesn't move and should, use the WD40.
    If it shouldn't move and does, use the tape.
  • As Daz says little bit of noise from the disk is normal, each time you refit the wheel you're going to get it lined up a tiny fraction different and that's what you'll hear, as long as it's free running you should be fine.

    wrt to gears, doesn't sound like a major problem, just check the chain to make sure there are no stiff links though. also make sure that when she's in the 'easier' gears at the back she's also on the granny ring at the front.
    Be happy, communicate happiness.
  • anjs
    anjs Posts: 486
    check to see if the chain is rubbing on the front mech.
  • daverey
    daverey Posts: 49
    Cheers for the help guys - much appreciated.

    Apologies for the stupid question, but how do I know that the wheels are back on perfectly straight (I've never had quick-release wheels before...).

    When I refit them, if they are fully into the dropouts and secure, is it fair to assume they are on correctly, or are there any other adjustments that should be made to straighten them?

    Ta
    Dave
  • You can definitely tell when QR wheels engage properly in the dropouts so you can't really get it wrong. With your disc brakes, your rotor won't sit properly in the brake caliper body if your wheel isn't on square so that's another good visual check.

    With regard to your brake noise, if it's an intermittent noise e.g. once per revolution, it probably just needs time to bed in. If it scrapes through an entire revolution, your calipers need realigning. Turn your bike upside down and give the wheels a spin, that's the best way to check.
    There is a time to surf and a time to wax your board.....

    '09 Trek Remedy 8
  • Daz555
    Daz555 Posts: 3,976
    With regard to your brake noise, if it's an intermittent noise e.g. once per revolution, it probably just needs time to bed in.
    I disagree - that would point towards a warped disc.

    Assuming the wheels on are on straight, a fairly continuous, very slight rubbing over the whole rotation will probably go once the pads bed in. However, more serious rubbing will likely need the calipers realigned.
    You only need two tools: WD40 and Duck Tape.
    If it doesn't move and should, use the WD40.
    If it shouldn't move and does, use the tape.
  • daverey
    daverey Posts: 49
    Cheer again for the quick answers.

    The noises do seem to be once per revolution - although the bikes are brand spanking new and it occurs on both wheels on both bikes.

    I think I'll just keep my eye on it and get it checked out when it goes in for it's 4-week check-up.....
  • Daz555
    Daz555 Posts: 3,976
    daverey wrote:
    I think I'll just keep my eye on it and get it checked out when it goes in for it's 4-week check-up.....
    Get those brakes bedded in and see how they get on.
    You only need two tools: WD40 and Duck Tape.
    If it doesn't move and should, use the WD40.
    If it shouldn't move and does, use the tape.
  • daverey
    daverey Posts: 49
    Quick update - I've just got in from work and checked the missus' bike to see if I can see what's making the tapping sound. It looks like when the bike is in the lowest 2 or 3 gears, the chain is rubbing slightly on the front deraillieur thing (the metal bit that pushes the chain into the different chain rings).

    Is it an easy job (remember I'm a complete novice) to adjust this to move it towards the bike frame and stop the chain catching? The last thing I want to do is knacker the gear changes?

    Dave
  • supersonic
    supersonic Posts: 82,708
    Derailer adjustment is a must learn skill really.

    Check the Park Tools website - great guide to it!