Originally Posted by DrIsotope

Easy way to check: take that little piece of chain you took off when you shortened the chain to install. Put it on the teeth of the big chainring, and try to slide the chain back and forth. It should only move a tiny bit, if at all. If you can slide it back and forth, or it doesn't want to sit all the way down onto the teeth, the chainring is worn. Note: even with alloy rings, this can take a whole lot of miles. Tens of thousands-- so long as you didn't use a chain far longer than you should have. I have two chainrings that have a bit of slop to them, both well byond 15k miles, and both who have lived through at least one chain used longer than it should have.