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I took part in my first bike event at the weekend, a very muddy "gravel" ride which by the end had my bike covered in mud! Rather than put it straight in the car, I took it to the muc-off tent and cleaned it with a little of their spray (mainly on the chain/cassette/crank), water, and a soft brush. When I got home I applied wd-40 to the aforementioned parts only.

Riding it today I noticed that my disc drakes were much weaker than they were before. Given that I haven't used any soap, or applied oil to the rotors, am I right to think that this should improve with use and that I haven't ruined my pads? They're only a couple of weeks old!

Thanks :)

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    Weaker as in you feel they wont stop you or weaker that they still stop but require more force / input from the lever? Had similar last weekend and it was just a minor adjustment needed, brakes feel better now than ever – Dan K Aug 22 at 13:08
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    Is the back brake much worse than the front? I suspect you may have got wd40 on the rotor when spraying the cassette. BTW wd40 isn't a good lubricant for bikes - it's only meant to lubricate for long enough to get things unstuck – Chris H Aug 22 at 13:58
  • @ChrisH WD-40 also make bike lubricants. It's unlcear whether the asker means "traditional WD-40 in the blue can" or "WD-40 brand bike lube". – David Richerby Aug 22 at 20:50
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    Do you have cable or hydraulic disc brakes? – Rider_X Aug 23 at 4:04
  • @DavidRicherby true, but assuming the original product when there's nothing to say otherwise is usually correct. For that matter so do muc off, so we're making the same sort of assumption there – Chris H Aug 23 at 6:12
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No, they probably will NOT get better without help.

The cleaner that you used is probably the problem. Maybe WD-40 overspray too; that stuff gets everywhere and it only takes a bit to ruin your brake pads. BTW WD-40 is usually NOT the best choice for ANYWHERE on a bike.

Disc brakes are great in a lot of ways but they have a couple vulnerabilities. One of these is that the pads can be contaminated and then the brakes don't stop well. Although you can soak disc brakes in mud repeatedly and they'll be fine, a drop of a solvent, cleaner, or lubricant can ruin the pads permanently.

No matter if they're "mechanical" cable-actuated, hydraulic with mineral oil or DOT; bottom line, the brake pad material is super sensitive to fouling. I got brake fluid on my (metallic material) pads years ago and brought them back to life by removing them and soaking in various solvents including alcohol and acetone and scrubbing with a toothbrush. Another time I got an unknown contaminant on organic pads, tried the same technique and... all I got was a bunch of contaminated solvents and another trashed toothbrush. I even tried sanding the pads and they still didn't work.

So, you can try the remove-soak-scrub-sand technique, or go buy yourself some new brake pads.

Just make sure the braking surface on the rotor is CLEAN before you put in the new pads.

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    WD-40 also make bike lubricants. It's unlcear whether the asker means "traditional WD-40 in the blue can" or "WD-40 brand bike lube". – David Richerby Aug 22 at 20:53
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am I right to think that this should improve with use and that I haven't ruined my pads?

No. You can't count on that happening.

You may have contaminated the disc or pad with some substance, there may be another issue. If both brakes are affected contamination is less likely as there is a lower chance you got something on both calipers at either end of the bike.

Remove wheels and pads and clean everything with disc brake cleaner. Check for wear on the pads - lots of braking in muddy, gritty conditions may have worn your pads prematurely.

Verify there is not some other problem with the brakes, if you have a mushy feeling at the levers, or the amount of pull on the levers to engage the brakes is excessive you may need a brake bleed.

If you still have poor braking, you'll need to assume the pads are contaminated and they need replacing.

  • It's both brakes, and they aren't stopping well regardless of force applied. I'll whip the wheels off and clean the rotors. The discs are mechanical. – SoqedHozi Aug 22 at 15:53
  • @SoqedHozi take the pads out, clean them and the calipers as well as the discs – Argenti Apparatus Aug 22 at 16:29
  • Brake cleaner from the automotive sector might help with the rotors but still you'd probably have to replace the pads. – Carel Aug 23 at 13:22
  • @carel, depends what's on the pad – Argenti Apparatus Aug 23 at 13:50

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