On Fri, 26 Feb 2021 19:30:00 -0800, AK wrote:

Today while riding, my rear brakes locked up.

While investigating, the rear tire blew up causing part of the rim on one side to split off.

The tech at the shop said the brakes had worn through the rim.

Seems hard to believe that hard rubber can wear thru aluminum.

Is that common ?

Common? Probably not, but it certainly happens. I don't think it's the rubber that wears through.
It's the grit that gets trapped in the pad that abrades the rim. This is mostly a problem if you
ride in the rain a lot, and even more if sand is used on the roads for winter-time traction.

Did the shop save the rim for you? If so, take a hack saw and cut through the rim some place where
it seems relatively intact. The wearing that I describe should be easy to see.

Let us know what you find out!
-F