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Hydraulic Disk Brake Performance Decrease

papadpapad Posts: 23
edited February 2019 in MTB workshop & tech
I've been riding an MTB recently that I didn't ride for over a year. The braking performance from both front and back has steadily been getting worse.

I need to pull the lever further and further inwards before the brake engages. Now the front brake is barely working.

I tried replacing the brake pads which had no effect. I bought a bleed kit and bled the brakes but again, no difference. It was my first time doing it so I may have made a mistake there.

Does anyone have an idea what the problem could be? Something other than the 2 things above?

The brakes are Avid Exlixer and are probably 4 years old.

Thanks

Posts

  • JBAJBA Posts: 2,778
    Elixirs are a pain in the derierre to bleed but work work well if done properly.
    The brake fluid could have absorbed water from the atmosphere so it is probably worth doing a complete fluid change rather than just a top up.
    Have a look on the Epic Bleed Solutions site. They have some excellent how-to videos.
    “Life has been unfaithful
    And it all promised so so much”

    Giant Trance 2 27.5 2016 ¦ Sonder Broken Road 2021¦ Giant Revolt Advanced 2 2019 ¦ Giant Anthem 3 2015 ¦ Specialized Myka Comp FSR 2009
  • I've changed from Avid to Shimano brakes because Avid are so much harder to bleed and get how I want them.

    As mentioned above, you may not have bled them sufficiently and fresh brake fluid might help. Even with old fluid, I'd expect them to at least partially function though. You may have air in the system/lever reservoir/caliper that you've not shifted as that can cause issues.

    From previous experience, it turned out my rotors were quite worn and when they were replaced things worked as they should. Not sure if that applies to you though.

    Also - have a look at the caliper and when you pull the lever, see if both pistons move (they may not move exactly the same amount but they should both move). Sticky pistons can also cause loss of brake power and need sorting.

    I've switched to SLX and XT brakes now as they are so much easier to maintain.

    Also make sure you're using the correct brake fluid as you need DOT fluid and not mineral.
    "Ride, crash, replace"
  • cyclecliniccycleclinic Posts: 6,865
    If there is too much lever travel they need bleeding. It is a 40minute job if all goes well. You bleed the caliper, the lever then the system as a whole if I remember right. Its so bloody awkward I have remind myself everytime I have to do one. A set of Shimano deore brakes out perform the avids. Hopes are lovely too.
    http://www.thecycleclinic.co.uk -wheel building and other stuff.
  • steve_sordysteve_sordy Posts: 2,288
    Pump the levers repeatedly. If the lever goes firm, then their is definitely air in the system.
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