Cleaning rims from brake surface

[ManBearPig]

Ciao.
My road bike has dark brake lines on front rim, I can't keep looking at it. Does anyone here ever clean them? And what can be used to get rid of brake surface?

[CharleyFarley]

(04-30-2020, 10:44 AM)ManBearPig Wrote:  Ciao.
My road bike has dark brake lines on front rim, I can't keep looking at it. Does anyone here ever clean them? And what can be used to get rid of brake surface?

Try rubbing alcohol. If that doesn't do it, 400 grit sandpaper should get them clean. You might want to install new brake pads, too.

[ManBearPig]

(05-02-2020, 11:07 AM)CharleyFarley Wrote:  Try rubbing alcohol. If that doesn't do it, 400 grit sandpaper should get them clean. You might want to install new brake pads, too.

Rubbing alcohol it was Dad gave some and it was enough to get rid of that brake surface. Pads look alright. Is there a rule of thumb?

[Painkiller]

The rubber marks on the rim actually "season" the rim. Improve braking performance and slow rim wear.

[CharleyFarley]

(05-19-2020, 04:57 PM)ManBearPig Wrote:  

(05-02-2020, 11:07 AM)CharleyFarley Wrote:  Try rubbing alcohol. If that doesn't do it, 400 grit sandpaper should get them clean. You might want to install new brake pads, too.

Rubbing alcohol it was Dad gave some and it was enough to get rid of that brake surface. Pads look alright. Is there a rule of thumb?

Not that I know of. I bought a new bike from them and the front brake grabbed at a certain spot. I told the mechanic and he said use rubbing alcohol, and if it's still a problem, use 400 grit paper. I did both and still the brake grabbed. I removed the wheel and the tire and tube, ran a micrometer around the rim to see if there was a low spot. Being a low end bike, you can't expect much in the way of wheels. It measured perfectly all the way around. I pressed the sides of the rim with my thumbs to see if the metal was soft in one place. It was good all the way around. So the only thing I can think of was that the metals used in the alloy to make the rims wasn't mixed properly, perhaps different metal characteristics. I don't know, I was just guessing.

So I could clean the rim and it would be fine for about two miles, just touching the brake two or three times, and the problem started again. Finally, I went back to the bike shop and ordered two better quality rims. The mechanic said I don't need them, and that all rim brakes snatch. I'd had two other bikes before that and never had the snatching problem as bad as this one was, so I don't think he knew what he was talking about. I told the shop owner to get me two better quality rims. That fixed the problem.

I even bought new brakes with replaceable pads. That didn't work any better than the original pads. I heard you can buy harder or softer pads. I don't know anything about those but I'd guess the softer ones leave that residue on the rims.

Brake pads can get a bit shiny, so I've removed them and sanded them lightly. That prevented squealing, but it's also recommended to toe in the brake pads. Slacken the mounting nuts, put a piece of cardboard (about as thick as a cereal box) between the rim and the trailing end of the pad, then squeeze the brake lever and tighten the nut, making sure the pad is parallel with the rim. That causes the leading edge of the pad to make contact with the rim, first.