Originally Posted by
cxwrench
No. That is not a wear indicator. As I've posted a few times wear indicators were not a thing when these rims were made. That groove, like all the others on this rim, is from wear, not manufactured. Stop posting incorrect information and do some research. Find a photo of a 280 or 330 rim with proof of a wear indicator.
No, that line in not from “wear”. It is too uniform to be made by any wear mechanism. Something imbedded in the pad would make a groove that is varies more. Look at the wear mark on the rim right above the second arrow. It is small and of variable depth and width. The black groove is even and follows the rim arc exactly. Perhaps Tomm Williams is mistaken about the rim model. The one in the picture has a definite wear indicator groove in it.
It's black because it has pad material in it. If it was a manufactured groove it would be thinner where the eyelets are and deeper between the spokes, following the rim wear. But...wait for it...it's the opposite. These rims are thin enough that they 'oil can' as they wear. That's to say they wear more where the eyelets are and slower between them. It's easily seen on many photos. Take a look at some photos and get back to me.
The line is black because it was anodized. And why would it be thinner or deeper? The groove is machined into the rim and they don’t vary the depth or thickness. A uniform groove is much easier to machine than one that varies.
The groove looks like the ones in this chart. And, if the groove were a wear groove it
should vary in depth and width as you’ve described. A uniform groove won’t form from braking.
To quote someone “this is not
my first rodeo”,