Mountain Biking - Disc brakes and cleaning

I've heard rumored that disk rotors are only their most effective when they're dirty and the pads are textured with grit.

I have noticed a dramatic decrease in braking power after I clean the rotors. Do you think this is from some complication from the cleaner (water with a tiny, tiny touch of dish soap), or is it due to the "dirty rotors perform better" thing?

PS - I make sure not to touch the rotors with my bare hands in order to keep off oils.

I usually use rubbing alcohol to clean my rotors and pads. That way whatever is chemical is left on the rotor evaporates off rather quickly. Also, I occasionally bend my rotor slightly and use bare hands to bend it back with no decrease in braking power. My guess is that the tiny bit of dish soap stays on your rotors and pads and creates a film that decreases your braking power. I don't think dish soap is a bad think to use just rinse them very well and quickly, so the pads can't absorb anything. I might be wrong and other people have more experience than I do, so correct me if i'm wrong

as raiyn would say...

ALWAYS USE DENATURED ALCOHOL to clean your rotors.

rubbing alcohol/isopropyl alcohol also works.

and i've cleaned my rotors with dish soap before and yes, i do notice that my brakes suck for a bit, but then bed in again.

as for the grit thing, i don't see how that would increase your braking performance - rather, wouldn't grit put little scratches on the rotor, decreasing the surface area of brake pad contact?

... which create a rough surface and an increase in friction, thus better stopping.

... which create a rough surface and an increase in friction, thus better stopping.

Thats what i was thinking.
Scratched rotors are a good thing, to a certain extent. But clean (with DENATURED ALCOHOL. Has to be in capslock on the bottle.), scratched rotors?

What happened to Raiyn anyway?

I think you might be onto something here. I recently changed my pads over on my mech. disc brakes. While i did this, i also cleaned the caliper and rotor using contact cleaner. After i finished and tested them out. They didn't stop the wheel rotating at all. Has this ever happened to someone?

I got a very small amount of WD-40 on the pads accidentally but i straight away sprayed it with the contact cleaner and didn't see any oil marks on it. So i assumed it dissolved and evaporated.

Aside that, should this be happening on new pads or are they screwed?

What I want to know is why people are cleaning their disc brakes?


I'm wondering the same thing. I only put effort into cleaning my rotors (i.e., with alcohol) when something gets spilled on the rotor/pad...and that is very rare.

I got a very small amount of WD-40 on the pads accidentally but i straight away sprayed it with the contact cleaner and didn't see any oil marks on it. So i assumed it dissolved and evaporated.

Aside that, should this be happening on new pads or are they screwed?

On brand new pads, no contamination, and installed correctly with clean rotors etc and so forth: no. There is slight break-in period where you wont stop very well, but once you 'burn in' your pads, the brake's performance should increase. Now say you were to get oil or WD-40 on your pad, I'm not sure any amount of solvent would remove it totally. The WD-40 would not evaporate along with the alcohol, only the mechanical action of spraying or rubbing, etc. would remove the oil. I myself have never gotten oil on my pads and therefore don't know how they react to cleaning. New ones are relatively cheap, I think you have new ones anyway, so just be careful next time? good luck.

If I ride on ashphalt the rotors/pads will eventually start to squeal. I toss a couple of lumps of mud into the rotors/pads and it cuts the glaze off the pads and they don't squeal anymore.

I've heard rumored that disk rotors are only their most effective when they're dirty and the pads are textured with grit.

I have noticed a dramatic decrease in braking power after I clean the rotors. Do you think this is from some complication from the cleaner (water with a tiny, tiny touch of dish soap), or is it due to the "dirty rotors perform better" thing?

PS - I make sure not to touch the rotors with my bare hands in order to keep off oils.

i usually use my pressure washer. good luck! let us know what works best for you.

If you got oil on your pads, a couple hard stops will burn the oil off, so don't worry about it.

I just ride my bike through an occasional creek crossing. Just let nature clean them while you're out riding! Voila! Haven't had any problems with mine yet.

Straight out of my Tektro manual:

After Riding
Remove any mud or other contamination from the rotor slot in the caliper. Clean the caliper body and b. rotor slot with brake / clutch cleaner

At Regular Intervals
c. Lubricate the brake level pivot with thick oil or grease.
d. Check to make sure all bolts re tightened to torque specifications.

I just ride my bike through an occasional creek crossing. Just let nature clean them while you're out riding! Voila! Haven't had any problems with mine yet.

Okay so this is weird, but true. I went out on the trails today (with my suckie brakes) and while going home I crossed the Huron River at a shallow point. From that point there was a short, steep hill through some residential area and then a downhill. WOW: my brakes worked like they did before I cleaned them!

IDk what the river did, but it somehow got whatever was on the rotors/pads off. The difference was very clear - no amount of washing with hose water had this effect.

It wasn't "burning" the oil off through riding either. It had to be something about the River's water... well now that I think about it I regret crossing a river filled with water that somehow removes residual cleaner off brake rotors that regular tap water can't :eek:;)

Weird but real