Originally Posted by
FBinNY
It really doesn't matter if they're wear indicators or not, you can probably use them as such.
The bottom of the groove most likely determines the minimum rim width. If you consider the idea that a chain is only as strong as the weakest link, the added braking surface material doesn't add any strength, so wearing it down to the groove depth can't weaken the rim. Of course there's every possibility that you can wear the rim beyond the bottom of the groove, but at least you know that wearing it to the bottom won't hurt.
BTW- all the above depends on the groove not being where there's added material on the inside, but IME I've never seen one that was.
Wow, I never thought of it that way, but you're right. I've seen pictures now that even the first generation ones had a circle drilled in as indicator, so that's probably not what these are. I wonder if the previous owner somehow managed to get something sharp on the edges of his brake pads that caused them. It's odd that they're all the same uniform spacing, positioning and depth (or at least close enough that I can't tell the difference). Since they are all uniform and I'm riding on the trainer for now (actually on rollers with a fork stand because I got the rollers and then never got the confidence to ride them like they're supposed to be ridden), I'm not using the brakes much. When I manage to go outside, I'll re-evaluate (or use a different wheelset). I'll check for the machined divot the next time I see the wheels (I left them at my office over the weekend), to see if that's still there and can go by that instead.
As I said in the OP, I bought these for the hubs (they're powertap hubs that were a good price and I've been wanting to try Zwift to make all the early morning riding I do staring at a wall in my basement a little less boring), and considered the fact they were laced to rims a bonus as it will get me up and riding faster, so, if I have to buy new rims and relace the wheels before riding outside, it will be a bummer but not the end of the world.