Wednesday, October 15, 2008

Q&A: Brake pads and rim wear

Q: Hi Jim,
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

I hope this helps,


Unknown said...

So are you saying that Kool Stop makes the softest brake pads? How are Aztec pads? Thanks.

Jim Langley said...

Not really. What I recommend is getting the pads that are right for you, your riding and your rims. That's why it's good to check with a good bike shop with local knowledge, other riders you trust, etc. Kool Stop is one company that makes nice brake pads, but there are others too. And Aztek pads have an excellent reputation too. Even stock Shimano and Campagnolo pads can be right for certain combinations. So, you'll want to do a little research to find what's best for you.

Hope this helps!

Unknown said...


Please help. The Aztecs don't fit XT MTB brakes. They are too think. I need thinner ones. The only option local bikes stores seem to have for my brakes are the XTR replacement cartridges, which EVERYONE says shred rims like no other. And that's been my experience as well.

I just need to know what kind of kool stop to get for my brakes, so I can order them online.

I would greatly appreciate any help Jim!

It's funny, I've read a lot of message boards, and this issue seems to be as complicated as "can a 32-bit OS access more than 4gb of ram," which is another debate on the internet.

Jim Langley said...

Hi JB,
You just need replacement V-type pads. Here's a link to some good Kool Stop ones I've used:

Hope this fixes up your brakes - and I can't help with the 32bit 4gig question. In fact my main PC just died ;-( Now I have to decide if I dare go with Microsoft 7.

Unknown said...

Thanks for the advice Jim!

Before you even responded, I ended up ordering these (all black):

(btw black is the softer material, red/salmon the harder, they also offer half and half)

I actually already had found your exact suggestion and seriously considered it.

However, I ended up going with the non-cartridge style only because they are more curved to the radius of rims and also they are longer (essentially bigger). I felt those characteristics would make them work better while at the same time be easier on my rims.

They were more expensive though.

Now I am praying that they will fit my XT brakes!

Jim Langley said...

Those should bolt on no problem, JB, but they do essentially make your bicycle harder to work on. The stock Shimano pads were cartridge style so it was simple to replace worn pads (a pretty common job since V-Brake pads wear out so fast). As you know, you only had to remove the keeper pin and slide out the old and slide in the new. These pads you've ordered mean you will need to fuss around a bit everytime you replace pads to get the position just right. Since there are literally infinite possibilities, it can be quite a job to get all the settings (up, down, in, out, angle, toe in) just right and you'll never get both pads exactly the same. This was the case with the old pads, too, but on those you only had to fuss with them once and then only replace the pads. So, if it were my bike, I'd leave the other type of brake pads on there for ease of replacement in the future. The brake makers didn't do us any favors my making the adjustment so infinite. It would have been much more impressive to provide a basic range of adjustment as was the case with the first mtb brakes.

Hope this is helpful,

Unknown said...

What happened to your computer? I might be able to help.

I would go with Windows 7. I think people that paid like $150 extra when they bought a computer during the last 2 years just to get Windows XP instead of Windows Vista got ripped off! They paid more for less. Don't listen to the hype.

Windows 7 has some modern UI features I have been waiting for.

Or just get a Mac.

Jim Langley said...

As best as I can tell, the hard drive is dying. I have to turn the PC on 5 or 6 times before it completely turns on. Sometimes it looks like it's turned on but when I try to open applications they freeze and I have to shutdown by flipping the on/off on the powerbar since the Microsoft Shut Down command doesn't work. It turned on today so I'm leaving it on. I think I somehow need to clone my hard drive on a new one in order not to lose all my programs. This is an older computer running Windows 2 Pro, but I like it when it works. I looked at Microsoft 7. Costco has a CPU for $599 but I'm not sure how I'd move my old programs, files over. I'd hate to have to buy all the old programs again. But, I'm still thinking about it in case I win the lottery.

Unknown said...

I recommend listing out an inventory of the programs you really need/use. It's probably not as much as you think. Then, look for free alternatives to some of it. There's all kinds of open source software out there like:
1. InfraRecorder - cd/dvd burning
2. AVG - antivirus
3. Audacity - sound editing
4. GIMP - bitmap graphics editor (i.e. photoshop)
5. Inkscape - vector graphics editor (i.e. Illustrator)
6. Google SketchUp - simple 3d editor (i.e. Autocad)
7. Notepad++ - great replacement for notepad.exe
8. PSPad - another text editor but with more features (I don't use it much)
9. Filezilla - FTP program
10. 7zip - does everything WinZip does and more
11. iTunes + Quicktime
12. You'll need a DVD codec though to play movies
13. OpenOffice - a Microsoft Office replacement, or you can buy an older version of Microsoft Office on Ebay (and older versions of Adobe software too maybe).
14. Chrome, Safari, Firefix, etc.
15. Foxit Reader - faster/lighter weight version of Acrobat
16. Then Windows of course, but there's alway Linux!

I honestly can't imagine needing anything else. Am I missing something? TurboTax maybe? Quickbooks? (Other than that, you don't need anything else, not Zone Alarm, or anti-spyware programs, all junk.) In the future, I HIGHLY recommend keeping backup copies of all your software; I can't imagine not doing that!

But what I think you are looking for is Norton Ghost to create an image of your hard drive and put that image onto another hard drive. However, If you ever try to put that drive into a different PC though with all different hardware, it isn't going to be happy and you are going to have to upgrade all the device drivers.

P.S. seriously, what other software to people use??

Unknown said...

And you can get a 320 gb HD for $50 brand new. That might be your problem, but no guarantee. Anyway, all that software is free, and you can get used older versions for Microsoft/Adobe/QuickBooks stuff on Ebay probably for pretty cheap, but be careful of illegal software.

You can also sign up for a class at a community college and get student discounts on lots of software with your email address.

Jim Langley said...

Thanks so much for all the awesome suggestions, JB! That list of programs is great - super helpful. Really appreciate your help,

Jim Langley

sk8brdkd said...


I have a question. Just the other day, I put new tires and new brake pads on my 1998 Schwinn Mesa. This was the first time I've ever attempted to work on my bike myself and the instructions on the brake pads didn't say which way the brake pads should face. I have the front brake pads facing one way and the back brake pads facing a different way. The back brakes work better, however, I'm having other issues w/ my front brakes which have nothing to do w/ the way the brake pads are faced.

Just wondering if there's a way to tell which way the brake pads should go? I have the kool stop brake pads.

Jim Langley said...

Hi sk8brdkd, most Kool Stop pads have marks on them, little arrows that should be visible on top of the pad and point toward the front of the bike when the pads are installed. Can you check and see if you have these? If not, please tell me what type of brakes you have or email me a photo at jim @ and I'll take a look. Just send me a large photo of the front or rear brake so I can see the detail and I'll check it out. Thanks! Jim

dan said...

Hi Jim,
Thank you for your advice thus far. Are you familiar with rim wrangler2 brake pads. They have some terrible reviews on the mtb forums. I'm going to roll with them for now and keep an eye out for premature wear and debris.

Jim Langley said...

Those are made by Avid, Dan, and Avid makes some nice brakes, so I would expect the pads to work okay. I haven't tried them, though, so I can't speak from experience. I would see how they work for you in your riding conditions before I would consider upgrading. Sometimes people give products bad reviews based on how the product works how and where they ride and if you ride in a different way you might have better results. So I would say you should try them and make up your own mind.
In cycling,