Pitted Rims


New Member
Apr 6, 2015
I've been having issues with metal fragments flaking off my rims and embedding themselves in my brake pads. This has been occurring since the bike was new (bought it last summer). I've never had this issue in my 33 years of riding bicycles. You can clearly see that the rim surface does not have a smooth finish. I'm guessing it's a manufacturer defect because I can't see how else this could happen. Has anyone else had this issue? The bike is a Specialized Crosstrail with 700c alloy double-wall CNC sidewalls pin joint 32h (whatever that means). Here is an example of one of the pads. All four look like this. The gouges are from when I previously removed fragments.

I would think getting the wheels, brakes, and tires replaced under warranty would be a good idea.

I've had these from time-to-time on various wheels and just popped them out with the tip of a sharp knife. I don't think it's anything to be concerned about, or that it indicates the rims are "defective". But you could always bring them in to your dealer and let him have a look.
I have a hard time believing it is normal. I've had to pick out large fragments on multiple occasions over a short period of time, some of which are 3mm+. For instance, I just picked out all the fragments this past Saturday and only rode the bike once for 7 miles and the front is starting to get loud again. I'm taking it back to the dealer this weekend.
OK, agree that rate certainly doesn't seem normal or acceptable. When I said I've had them before, it was maybe a coupleof pieces of about 1mm size in the brake pad over 5K miles. Agree you've got a warranty claim here.
Why do you think it is metal fragments flaking off your rims? Could it be, instead, that metal fragments are embedded in the brake pads, and are gouging the rims? I mean, it would seem to me very difficult for a smooth rim to suddenly gouge a brake pad. It is far more likely that the reverse is true: the brake pad is contaminated and gouging the rim.

I suppose it could have started with the pads, which damaged the rims, etc. etc., but why would pads have metal in them? Regardless, I'm going to ask for a new set of rims and new pads.
I just stumbled across another forum where the person has the same problem. People are saying it is the brake blocks/pads causing the issue. It isn't clear where the metal fragments are coming from though, but it sounds like the cycle starts with the brake blocks. Someone recommended the Koolstop Salmon blocks to mitigate the issue. Question is if I get new blocks, can the rims be resurfaced or are they now trash?
I just ordered some Kool-Stop Dual Compound Mountain pads, which will be here tomorrow. What should I use to debur the rims? Fine grit sandpaper followed by a Mavic block?
Well, you never posted photos of the damage to your wheels. And I don't really know what to do about them. To me, this is like the brake pads on a car ruining the brake rotors. Sometimes you can resurface the rotor, sometimes not.

If it were me in your shoes, I would replace the wheels and the brake pads, and be careful to check the brake pads frequently and replace them in accordance with the generally accepted guidelines for same. Brake pads don't last forever. They do wear down.

I was going to post a photo of the rims, but my phone camera isn't good enough to catch the detail, so the damage wouldn't be obvious. It is relatively minor and seemingly repairable, so I'm going to pick off any loose fragments and lightly sand the rims. Hopefully that in combination with the new pads will mitigate the issue. BTW, this bike is less than a year old and has maybe 75 miles on it.
Suggest you have the LBS where you bought the bike look at the rims before you do any sanding on them. With less than 100 miles on the bike, I think the wheels have a defective finish and should be replaced under warranty. Most LBS dealers are good about correcting these issues. You bought a major brand bike and deserve good customer support. Even if the bike is out of warranty they should be willing to help correct the problem.

Note, I'm assuming the bike has been stored indoors, not left outside or ridden in sand at the beach.
I may go ahead and take it in after all before attempting to sand them. That would likely void my warranty. They are being cooperative, its just a hassle to drive to their shop 30 minutes away. Yes, the bike is always stored indoors in my spare bedroom. Still looks brand new.
What? You've never heard of metallic brake pads?

Just kidding.

Aluminum is soft. It smears easily.

Rocks and road grit get embedded in the pads and smear off and gouge the brake tracks. And the rims wear down. That's why some rim manufacturers put Brake Warning holes in the brake track walls to gauge the wear.

As far as pitting goes, exposure to salt or other corrosive elements can cause aluminum to pit.

There is an outfit that re-surfaces rim brake track with a material additive process. You'll have to Google to find them. I'm guessing it's an anodizing process followed by grinding. I have no idea of the cost and would guess the rims have to be un-spoked and shipped off bare. That's a load of work and money right there. New wheels would probably be more cost effective.

Simply dusting off the brake tracks with a stone will work as long as you do not remove much material and carefully clean the wheels after stoning...you are embedding garnet or carborundum or whatever you stone has vitrified in it right into the alloy. A paper polish or such would be recommended after stoning.
I'm sorry, pitting was the wrong term to use. The aluminum is chipping/peeling/flaking off.
I've seen anodized layers lift and separate (sounds like a bra design!).

Most aluminum stock is extruded and rolled so it's possible there is a boundary layer delamination thing going on, but I'm still guessing the brake pads are getting rock shards and grit embedded in them and acting as a lathe cutting tool or a grinding wheel and tearing up the brake track.

The damage is only occurring in the brake track area, correct?

Let's hope you can stone off most of the smearing damage and new pads reduce the wear you're experiencing.

If the damage continues I would press the issue with your dealer and/or the rim manufacturer.
I took the bike to the shop today and they said it is normal. Not really what I wanted to hear, but what they said makes perfect sense. Just as the previous poster said (sorry, can't see your name while typing this on my phone), sand, rocks, etc, are getting stuck in the pads, and the pads are damaging the rims, which is resulting in metal fragments coming loose and getting stuck in the pads, the metal damages the rims further, etc. I ran a very fine file over the rim brake surfaces to remove any coarse flakes, then followed up with a light sanding (1000 grit), and isopropyl alcohol. Then I installed my new Kool-Stop blocks. I can tell by looking at the Kool-stop pads that they are going to be much better than the original pads. They have a leading edge that curves inward and sweeps away any grit that gets carried up towards the pad, and just behind that the pad has triangular shaped grooves that channel debris (and water I'm assuming) away from the rim. I'll see how it goes for a few rides and post back soon with the results.
Aluminum is soft. It smears easily.

Rocks and road grit get embedded in the pads and smear off and gouge the brake tracks. And the rims wear down. That's why some rim manufacturers put Brake Warning holes in the brake track walls to gauge the wear.

As far as pitting goes, exposure to salt or other corrosive elements can cause aluminum to pit.
Especially the soft rims used on lower end hybrids.

Mossman, it looks like your bike is clean, and the Kool-Stop pads should help. But, a word to the wise, for rim and brake pad life (and braking effectiveness), clean your rims and brake pads after they get dirty.
I'll be sure to clean them after each ride. A quick spray with the hose and/or compressed air should do the trick.
15 miles with the Kool Stop dual compound blocks and so far so good! No metallic sound and whisper quiet braking. Highly recommend these pads.