ivan_yulaev

Well, after my ten mile commute in the rain today, I noticed that both my rims have a very distinctive black scratch worn into them. Not too deep, just deep enough to stop my fingernail. Is this cause for concern?

For the record, I very rarely ride in the rain.

neil0502

Have you checked all your brake pads to see what, if anything, is embedded in them??

ivan_yulaev

Just did. They did not have any visible chunks embedded, but they did have a slighly raised section. I flatened them on a piece of sandpaper, and put back in.

It seems the rims still have the lengthwise ridges on them, as they are fairly new (<500 miles). Oh well, if they wear down, no sweat, they are cheapies.

neil0502

Raised section, huh? Are they aligned properly in the up-and-down direction? That is, do they strike the rim in the center of the braking surface? There's a drawing here that will indicate what I mean. They call it "Vertical height alignment." If that's correct on your bike, there's no real reason (that I can think of) that you should have a raised section.

Does the raised section run the long way on the pad or the short way? L-R or up-down?

ivan_yulaev

Long way. It is a line (maybe 2mm wide, tops) that runs lengthwise.

I alighn them by eye, pretty careful about it, but not extremely accurate...

neil0502

Hmmm. Maybe the seam where your rims are welded (it runs perpendicular to the direction of the rim itself) is slightly rough. Is it on both pads (left, right) on both rims (front, back)? If so, that's my guess.

That could put a bit of a notch in the pads. Check it out carefully. If it's rough (you can feel it, or it's raised enough that your thumbnail catches it), you might want to talk to your local bike shop and see if they think it's safe to sand it down.

If not, I'll stick with "Hmmmm."

ivan_yulaev

It is parallel to the rims, a perfect circle going along the entire rim. More pronounced, although present to a certain extent on all rims. Almost as if I had a small diamond chunk stuck in the same spot on each pad, although I know that's not the case, as I examined the pads and they were quite clean.

Perhaps when I put in my new calipers I failed to flatten the pads, and now have an groove due to the raised line on the pads. Well, I'll keep my eyes open. How thick are those rims anyway?

jumbolugs

A couple of years ago, 3 days into a 4-day trip I suddenly noticed a groove worn into each of my rims (they were quite new wheels).

After anxiously checking my brake blocks for embedded flints etc. I realised that the grooves are actually wear indicators. When you can't see the groove anymore it's time to get new wheels as it means the rims are worn to a dangerous degree.

I think the reason I noticed them when I did is that the brake blocks had started to wear significantly and leave black smears on the rims, and the black rubbery deposit made the grooves show up. When the wheels were brand new I didn't notice them!

neil0502

That's a good call, JumboLugs, but didn't your wear indicators run 'north-south,' rather than 'east-west??'

Ivan, if I were you, I'd be dropping by my local bike shop. Thickness of the rims varies by rim. Somebody ought to look at this and see if there's a readily identifiable problem.

Good luck!

ivan_yulaev

This makes a lot of sense. Mine run parallel to the rim's direction, a straight line along the rim. There's really no explanation for them being there. I think it is because of all the dirt when it rained, they finally showed up (my rims were almost black when I got home, after I washed them off I saw the line.

Anyway, flattened the pads on a piece of sandpaper, should be fine. I'll drop by the cyclery at some point...

bostontrevor

Eh, unless you determine that it's the wear indicator, it's nothing to be terribly concerned about in my opinion. (And feven in that case it's just something to be aware of.) That's what wet grimey braking does. People pay money for machined rims for improved braking performance. Look, you just did it for free!

Make sure there's nothing left in your brake pads and be thankful for nature's bounty and move on.

Wheel Doctor

What kind of rims are they? What kind of brake pads do you have.

Jude

DieselDan

My guess, dirt got trapped in the wear indicater from the rain.

ivan_yulaev

This is the conclusion I have reached. I bet it has always been there, just didn't see it because there was no dirt in it. After yesterday, my rims were VERY dirty (the color of my wheels, except the rims are not anodized black ) After wiping the dirt off with a cloth, then, I noticed it.

I have Alex DA450 rims and the stock pads with Shimano 105 calipers.