noobinsf 

I know there is a lot of discussion on this topic already, but I am looking for reassurances from experienced eyes. I have this wheelset with unknown mileage, and these are Mavic Open Pros laced to Ultegra hubs. It looks like there is no daylight between the braking surface and a straight edge, but I’m not sure what to think of the ridges. What do folks think?

noobinsf 

Salamandrine 

I can't really tell just from photos, but that scratching looks pretty trivial. It comes from riding with rocks stuck in the brake pads.

Ideally you'd measure the sidewall thickness and the scratch depth. Can you estimate the depth of the scratches?

repechage

Measure them with a quality digital caliper
say halfway between the valve and the rim joint
keep track, don’t worry, watch

noobinsf 

Thanks, guys — the scratches don’t look too deep. I can run my thumbnail over the track against the grain, and my nail doesn’t catch. The best reading I can get with calipers says 2.5mm thickness or thereabouts, but it’s impossible to get a 100% accurate reading due to the lip.

Dfrost 

Measure the overall dimension of the rim + a small ball bearing that fits between the lip and “floor”. Then measure the ball bearing alone and subtract. Voila...

Regardless, I’d also say the rim looks fine.

randyjawa 

True enough but there are other things that will cause this kind of wear.

Pads, themselves, when left to suffer the ravages of time can, and darn well will, become very hard. I learned this the hard way, a few years back. The pads were so hard that they started scratching up a set of near NOS rims immediately. I filed the pads, hoping to remove the hardened surface, but to no avail. The pads had expired, as nearly as I could tell.

Anyway, just wanted to add that and, were it me, the rims will still be rolling along underneath me and my bicycle.

Salamandrine 

Those must have been some very old pads! Sure, I believe that could happen. Rubber attempts to turn into hard rubber - like a comb - if given enough time. I've never seen them hard enough to scratch a rim myself. They generally stop working long before that.

Most of the time the issue is going to be gravel or other debris stuck in pads. Could also be glass or metal shavings.

To be honest I think a lot of this modern fear of rim scratching seems to be the result marketing. Both the disc brake manufacturers and the bike companies that want to sell you a new bike with disc brakes have an incentive to make people think rim brakes are bad. .

steve sumner

I'd sand the rim smooth and keep using it, sand the pads while yr at it, some of the debris in the pads
is too small to see well