Recently, I decided to replace both the chain and cassette on my bike. The chain was worn, it could be lifted off the large chainring, and thought I’d do the cassette at the same time as it too had worn.
I didn’t however check the chain ring. I’d last changed the inner ring back in 2017. Now, almost to the day, it’s needing changed again. I immediately recognised the sound, but it wasn’t as bad as last time, but the same grind noise I heard back then, so realised the chain ring was clearly on the way out.
Riding, gives a distinct metallic scraping noise from the front chain rings and looking at the teeth you can see a wear pattern. The new chain has trouble meshing with the wear, giving a scrape as it tries to settle in.
So, it might get better as the chain beds in, but I’ll change the ring.
A good clean out of the bikes drive chain and a new bottom bracket, as you might as well while your crankset is off.