Bicycle Mechanics - pros and cons of using sandpaper on old brake pads

Over time, the rubber of brake pads hardens, and thus becomes less effective at braking. The hardening takes place especially on the exterior of the rubber (sort of like cheese) and is specifically problematic on the part of the pad that contacts the rim; braking effectiveness is compromised.
I've found it useful to buff the pads with sandpaper to remove the thin hardened layer, and have noticed significantly increased braking performance on some old bikes whose pads I've scrubbed.

The downside: I think it's possible that grains of sand can get stuck in the rubber, and pressed into the pads, to kindly grind down your rims later. I've noticed this in a set of pads that I sandpapered yesterday. Two explanations:
I'm using the same piece of sandpaper that I have for quite some time, and the sand on it has become loose from so many uses, and thus pieces of sand dislodge and get caught in the pads, pressed into the rubber.
There was already grit in the pads from being used for a long time, and the sanding just removed some of the rubber around the grit, making its presence in the pads more obvious.
So, perhaps there'd be no problem if I were careful to use newer sandpaper when I do this. Or maybe there's no problem at all, and it's just old grit. (I've been picking up the grit, whatever it is, with the point of a razor blade.)

What do y'all think?

Sandpaper, whether new or old, is likely to leave grains of the abrasive in the brake pads. You can minimize the problem by using emery paper or similar abrasive paper intended for metal finishing since the abrasive grains are glued more firmly than on wood finishing paper but it's still a possibility that some will come off.

Your best preventative is to wash the pads thoroughly with soap and water and a soft brush after you abrade them That should wash away almost all the abrasive residue.

Okay, good thoughts. I'll look into Emery paper.
I do doubt that washing with soap and water will help that much, in the cases where grains of sand are left embedded in the brake pads - they're usually stuck in there pretty well.

Use a file.

I've used sandpaper in the same manner you used it.I didn't really notice the grains getting stuck in the brake material.I think I'll use a file in the future.Thanks.Charlie

Use a file.
+1

A good sized file works well and likely what i'll stick to in the future. I've gone the sandpaper route before, never noticed anythings stick in them, but better safe than sorry. Plus the file is a good firm base to scrub against.

I'd probably go with a file, too.
I've not noticed grit stick in most of the brake pads that I've sandpapered, which is why I wondered about
* the sandpaper being old and falling apart more
* different compounds of brake pads, and how worn they are.

A really interesting example is from an old bike whose parts I just cannibalized. The rear-wheel brake pads, which hadn't been much worn-down from use on the bike, got lots of grit embedded in them. The front-wheel brake pads, which had been worn down a lot, sanded cleanly without getting any of the pieces of sand stuck in them.

A few years ago I had some Dura-Ace and Ultegra pads that were way too hard when brand new. I think Shimano pads are better now but I still routinely replace them with KoolStop pads, they're softer, stop better, and last a long time.

Al

Use a file.

I use fingernail emery boards. They have just the right grit, they have a nice square surface, they're easily found and the price is right.

After sanding (or filing, emery-boarding, whatever), I always scrub with a Scotch Brite pad + simple green or similar. Scrub the rim/braking surfaces, too.

I use fingernail emery boards. They have just the right grit, they have a nice square surface, they're easily found and the price is right.

....and you always have one in your pocket. C'mon, you can tell us. :D

I think Shimano pads are better now

Al

nope - they're still terrible. brand new ultregra pads, less than a 1000 miles, and i can barely stop. same with my last pair of shimano pads. they should really do something about the quality of these pads - it's pretty bad.

nope - they're still terrible. brand new ultregra pads, less than a 1000 miles, and i can barely stop. same with my last pair of shimano pads. they should really do something about the quality of these pads - it's pretty bad.
Yeah, I just stuck some Ultegra pads on the front brake of my commuting bike (http://www.unc.edu/~cupery/pics/bikes/Miyata_commuter/) because it's got some not-so-powerful sidepull brakes. The pads have good contact area against the rim, but don't brake any better than the old crappy pads that came with the brakes. Surprising. I can see why people go with Kool Stops.

Use a file.

Unless you remove the pads from the brakes, using a file also makes it easier to maintain a flat surface on the face of the pad.

Use a file.
+2

I use the emory cloth and clean the pads with the air compressor. Dont forget to clean the rims too...I like automotive brake cleaner, or any other strong solvent.

Thirded (or fourthed?) on the file recommendation. I also scrub the pads with dish soap and an old toothbrush afterwards. Before all that, though, I dig out any yuckies with a metal dental-pick type tool.

Use a file. --- After filing I wipe the brake pads with alcohol. It removes the filings and leaves the surface of the pads dry and clean to get traction on the rims. Sometimes just alcohol alone works.

Over time, the rubber of brake pads hardens, and thus becomes less effective at braking. The hardening takes place especially on the exterior of the rubber (sort of like cheese) and is specifically problematic on the part of the pad that contacts the rim; braking effectiveness is compromised.
I've found it useful to buff the pads with sandpaper to remove the thin hardened layer, and have noticed significantly increased braking performance on some old bikes whose pads I've scrubbed.

The downside: I think it's possible that grains of sand can get stuck in the rubber, and pressed into the pads, to kindly grind down your rims later. I've noticed this in a set of pads that I sandpapered yesterday. Two explanations:
I'm using the same piece of sandpaper that I have for quite some time, and the sand on it has become loose from so many uses, and thus pieces of sand dislodge and get caught in the pads, pressed into the rubber.
There was already grit in the pads from being used for a long time, and the sanding just removed some of the rubber around the grit, making its presence in the pads more obvious.
So, perhaps there'd be no problem if I were careful to use newer sandpaper when I do this. Or maybe there's no problem at all, and it's just old grit. (I've been picking up the grit, whatever it is, with the point of a razor blade.)

What do y'all think?

Use a file, no grit, no scratching. End of story.

Tim