You recommend keeping the rims and brake pads clean for the best braking and to limit rim wear. But, how does aluminum from the rims accumulate on the brake pads if the aluminum is the harder of the two surfaces? The reason I ask is because for the second time now (four or five days apart) I started to hear and feel the sick metal-on-metal grinding from my front pads. The first time I heard and felt it, I ran a piece of sandpaper lightly over the pads and the noise went away, problem solved, I'm a genius - not! Now a few days later, the same sick grinding sound comes when I apply my front brakes.
I took my wheel off and can clearly see a piece of embedded aluminum on the face of the brake pad with a very light corresponding wear ring on the rim itself. So again I ask, where is the aluminum coming from? Especially since I don't use my front brake nearly as much as my back and I've not had this problem on the rear rim or brake. And, is this a continuous problem that I need to be fearful of destroying my rim and brake pads? Is there a ultimate solution to this annoying problem?
Thanks for your time,
A: Hi Gary,
I believe that there are 2 factors. 1. Some brake pads are way too hard and as they age they get harder and I think these can wear the rim over time and remove some aluminum. Keep in mind that even a soft material can wear a harder one if it contacts it enough, like water on stone for example. But, I think softer pads that wear out faster are preferable to harder ones. The other issue and probably the more important one is that the wheel picks up dirt and sometimes bits of gravel and that gets into the brake pads, too. Then, the surface of the pads becomes a bit like sandpaper and they begin to sand away the rims removing aluminum and embedding it into the pads, too.
These issues definitely lead to rim wear and left unchecked you will wear out your rims if you ride enough. I've done this and seen it many times on road and mountain bikes. To prevent it I use softer brake blocks and check them and dig out bits of debris and aluminum whenever I am doing routine maintenance. Something else you can do is rebuild your wheels with ceramic rims. These are very expensive and don't come in all sizes but they have a very tough braking surface that holds up much better to the brake pads. Of course, an altogether different approach for people with compatible bikes would be to install disc brakes and stop braking via the rims. But, you need the right frame and fork for this.
The best bet for most people is to keep a careful eye on the brake pads and rims, checking them about every time you lube your chain (weekly for frequent riders). Keep the rims clean (alcohol works great for removing rubber deposits and general grime) and keep the pads free of grit and aluminum (pick it out with an awl or sharp blade) and you'll get the most life out your rims possible. And, as I said, in my experience, softer pads wear rims less than harder ones. Your bike shop should be able to offer different pads and explain which are softest, or you could sample them. They shouldn't be overly expensive. I've found that with the right brake pads I have a lot less problems with grit and aluminum getting in the pads and rim wear, too. FYI: My road bike sees the most miles and it has Shimano Dura-Ace brakes on it from about year 2000. The brake pads I'm using are Kool Stop "Dura-Type" #KS-DURAB. They make pads for most brakes www.koolstop.com
I hope this helps,