If your chain is close to the 1/8th mark, you’ll need to check
your chainrings for wear. These chainrings have seen some wear
but they still have some miles left in them. A completely worn
chainring will have a ramp shape the trailing edge of the teeth
where the chain pulls. While the chainring may work with your
existing, worn chain, installing a new chain onto a worn chainring
will often result in skipping, as the two do not line up properly.
Single-ring setups may need to be replaced more often than 2X
or 3X systems since the chain is always wearing on the same
chainring. Especially with narrow/wide-style chainrings, a worn
chainring can become not only noisy, but also less effective in
keeping the chain from derailing.