Originally Posted by Mikefule

First, check that your existing chain is clean and well lubricated, and that the chainring and sprocket are also clean. They can pick up road dust and grime which mixes with the lubricant and creates a paste that can make a grinding noise and cause wear. A good clean may get rid of the grinding noise.

Second, if you need to replace the chain, it does not mean that you automatically need to replace either the chainring, or the sprocket, or both. Look at them to see if they need replacing.

An aluminium chainring or sprocket will wear faster than a steel one.

Look at the teeth: are they still symmetrical, or have they started to to wear into hooks? If they have started to hook, then it is time to replace.

Chains are a routine item to replace; chainrings and sprockets less so.