I've been riding every day since early last autumn,
and maybe five or six times I've used a very light weight
sandpaper to scrub the rims and brake pads, after a nasty rain ride.
Cleans them right up, and makes them quiet again.

So today, my LBS said "NO - don't do that. Use acetone
on the rims, and the sandpaper on the pads."

I asked if I'd damaged the rims; he said no, but don't do it again.
Okay - I've seen elsewhere here that Scotchbrite pads and/or
alcohol are good to clean the rims.

Sometime after the conversation (naturally), I thought,
"but won't acetone melt the tires?" (I'm no chemist)

I've got to get my rims clean after riding in the rain.
What do you recommend?

Green Scotchbrite, and rubbing alcohol. It gets rid of the brake residue and gunk very well. Do not use sandpaper, you will hasten the demise of your rims. Acetone is O.K., but you should do it outdoors and wear gloves. Not good stuff. I've tried lots of stuff over the years and so far the Scotchbrite/alcohol combo works best for me.

Windex works well as does rubbing alcohol(Easier on you and the rubber than acetone). A little sandpaper does not hurt every now and then (Think of how much grit ends up on a well used MTB rim) but if you use sandpaper wipe it down with alcohol after.
My favorite for dressing pads is a bastard cut file. It will take the pad down smooth in a flash and leaves nothing on the pad. You can get a cheap one for just a couple of bucks.

Good answers - thanks.

I really like Acetone, it increases your braking SOO much and cleans really well.

So - it won't melt the tires?

I don't -think- that it will acyually dissolve the rubber used in tires. Well, not all of the rubber compounds in the tire (although it's particularly hard on natural latex). But what it will do is cause the rubber to harden faster than it would from simple age.

The rubber compounds in tires are not 100% cured. Mostly, but not all the way. There are oils in the rubber that allows them to remain flexible, soft, and grippy. These oils will naturally evaporate with time, which is why rubber hardens with age. (Well, this plus oxidation makes them harden in time...)

The acetone (a solvent) mixes with, breaks down, and thins some of these oils. When the acetone evaporates (which it does, you've noticed I'm sure, very quickly) it takes some of the "good" oils with it. The result, dry, hardened tires suffering from accelerated age.

Yes, the rubbing alcohol does this too, but to a much smaller extent. It's also a lot less hard on the person using using it than the acetone is.

You can also very effectively thin the alcohol with water; they mix very readily. The sharp of eye would also have already noticed that most bottles of rubbing alcohol already are mixed with water. Usually about 30%.

-Erik

Soapy water (dish detergent etc.), a spongecloth & scrubbing brush works well for me. Also I check the brake pads to make sure nothing has become embedded in them before giving them a scrub. I don't go overboard cleaning with solvents as the enhanced braking this gives soon fades.... and I'll get caught in the rain soon enough anyhow.

Cheers,

Ed

I usually use an old wet rag with just water to wipe the rims down first. Then, I use a rag with rubbing alcohol to clean the surfaces a bit better. I try to avoid getting alcohol on the tires either way.