When to change brake discs

neiglass
neiglass Posts: 10
edited October 2016 in MTB workshop & tech
Okay so after about 1 year of racing and training hard on my rig the brakes don't seem to grab properly anymore. When braking with the front brake as hard as i can, even with two fingers, I can't even lift the back wheel off the ground when shifting my weight violently forward. We're talking xtr race brakes on a 21 lb (9,6 kg) scott scale. I've replaced my brake pads multiple times and cleaned the rotors with disc brake cleaner after every ride for a week. Ischanging the rotors and pads the only solution? I've also tried filing the rotors with rough sandpaper.

Comments

  • cooldad
    cooldad Posts: 32,599
    It's not a rig, it's a bicycle. Stop using anything except water to clean the brakes. Chances are you're contaminating the pads with whatever you're using. Clean the rotors with isopropyl alcohol, replace the pads, bed them in properly and see.
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  • The Rookie
    The Rookie Posts: 27,812
    The discs are steel, unless they are worn right out and too thin (I doubt it) then there is nothing else that can go wrong with them that would reduce the braking.

    The discs on my commuter I've had for 7 years and they've done about 6500 miles, the disc on the back of my MTB I've had a similar time, those three were bought used.
    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.
  • poah
    poah Posts: 3,369
    clean discs in fairy or some other detergent then sand them. buy new pads and bed in properly. do not clean with brake cleaner or any other product particularly when the wheel is on the bike.
  • swod1
    swod1 Posts: 1,639
    Sounds like you have not bedded the brake pads in enough, you've then gone and glazed them which has reduced the braking power.