So my mechanic and I bled my brakes after it always needing to be pumped before it brakes, brake fluid came out black and seemed to have metal shavings at the bottom. The only problem now is weirdly enough it still needs to be pumped before it brakes sharply. Any ideas why this may be happening? I bled my brakes after quite a long time just so you know. Also one more thing is that we tried switching up the cables to see if it was a problem with the brake lever but the problem just pmping brake just jumped to the other lever. Cheers, Naeem

  • When you first pump, is it squishy/spongy then comes on hard with pumping, or does the lever travel too far, but not squishy? (Squishy means there is air in the system)
    – mattnz
    Aug 19, 2021 at 23:10
  • 1
    Did you do a full fluid flush or just a bleed ? Black fluid would require a full flush, possibly several to get it clean.
    – Criggie
    Aug 20, 2021 at 1:55

1 Answer 1


When a brake needs to be pumped like that and then feels better, the typical reason is that there's air in a reservoir type system such as Shimano and some others. Pumping it moves the air up into the reservoir at the lever.

It could be a problem with the bleed you did, such that some air was left and if you could avoid that, the problem goes away. Extremely dirty fluid and metal shavings suggests other potential problems that could result in air getting in, such as a damaged seal or piston. If that is true the problems are likely to persist until the brake or the applicable parts are replaced, if they're available as repair parts. Some brakes do have rebuild type parts available, but most do not.

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