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I've had this problem for some time now, both of my disc brakes on my MTB barely work, when i pull the front lever for example i can still push the bike very slowly. They have been properly setup like the tension in the wire and all and the pads seem to have plenty left on them. I have tried cleaning the pads and discs with rubbing alcohol and the problem still remains. Any ideas on what i could do would be appreciated.

Update So I decided to try and buy new pads and after going up and down a local hill a few times and bedding the breaks in, in a few minutes I managed to be able to do an endo. Still unsure why the other pads behaved as they did as before I installed the new ones I compared the new and old ones and the old ones had pretty much the same amount of compound left on them.

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  • Have you adjusted the pads correctly - wound in the inboard pad (that does not move) then adjust the outboard one? New cables can make a big difference.
    – mattnz
    Jul 1, 2017 at 22:19
  • Have you run them for a while now, and the brake pads are simply worn out? Did they deteriorate gradually or quite suddenly? Did you do a really dirty ride just before they deteriorated?
    – Criggie ♦
    Jul 1, 2017 at 22:45
  • @mattnz I have adjusted them as best I can, the inboard one is as close as i can get it without touching the rotor and the outboard one is 1 mm or so away from the rotor. New cables you say? Might be a good shout
    – Kacper Dluzak
    Jul 2, 2017 at 11:19
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    @Criggie I'm gonna be honest I cannot remember, as i said the pads have ~3-4 mm of compound left on them which is why I'm not sure as to what causes the problem.
    – Kacper Dluzak
    Jul 2, 2017 at 11:21
  • Could it be that there isn't enough oil in the breakes? ( don't know if they are hydrolic brakes...)
    – Mech_Engineer
    Jul 3, 2017 at 9:23

2 Answers 2

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Even if they were heavily contaminated, pads should have enough grip to lock up against hand pressure.

My first guess is that your pads are worn to nothing and you're trying to grip the rotor with the pad holders. New pads would be the first order of the day.

The second thing would be that you've tightened up the slack adjustment too much or that you've clamped the brake line at the brake so high that you have no brake travel left. So you're essentially hitting the limit of the brake when you squeeze, rather than grabbing down with your caliper.

I'd take it to your local bike shop. A one minute look over would tell them if you needed new shoes or brake cable adjustment.

Since replacing your pads resolved it, it looks like either pad contamination (or brake setup) was the problem. To make sure your rotors don't recontaminate your new pads, I'd clean your rotors with some isopropyl alcohol (rubbing alcohol) from your local pharmacy / drug store and make sure not to get anything oily (such as fingerprints) on the rotors.

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  • The pads still have a decent amount of compound left ~3-4 mm so not sure if it's that. As I've said above the pad that doesn't move is adjusted so that it's as close to the rotor without touching and the one that moves is about 1 mm away from it. I'll take it along to Halfords, probably my closest shop.
    – Kacper Dluzak
    Jul 2, 2017 at 11:26
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    New pads did the trick :)
    – Kacper Dluzak
    Jul 12, 2017 at 19:19
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Have they worked OK in the past with similar pads fitted? It sounds to me as if contamination of the pads and/or rotors could be causing the problem. Maybe strip off the rotors, give them a really good clean, fit a new set of pads and try again. Hope this helps..

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  • Thanks for the reply. They are the exact same pads I've always had and they used to work perfectly. i did give the rotors a really good clean the other day with rubbing alcohol and problem still persists. I just don't wanna go buying new pads in case that doesn't fix things
    – Kacper Dluzak
    Jul 1, 2017 at 18:13
  • Given that they're cable brakes it's the easiest and cheapest thing to try really (new pads). You could try sandpaper, a blowtorch for ~30 seconds and some more rubbing alcohol to see if you can get some bite back. If you clean your rotors with alcohol you may need even longer bedding in time as pad compound is deposited on the rotor as part of that process.
    – Chris
    Jul 1, 2017 at 18:48
  • I think I'll just give new pads a shot. Thanks
    – Kacper Dluzak
    Jul 1, 2017 at 19:03

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