Originally Posted by
Gummomarx
Within the last few weeks, replaced my chain/crankset, cassette and chain. On the last two rides, I've noticed a chirping noise at the back wheel area when pedalling only and more pronounced when changing gear.
Back to the original question. I have experienced this myself when the pulley wheels have not been lubricated. The louder squeaking while changing gears is a symptom of dry bushings in the pulley wheels. Despite the oily chain, the bearing surfaces inside the pulleys are dry. This has happened to me several times in my 50 years as a cyclist. Despite the gunk, the pulley wheels in the OP's picture are not all that worn. If they were cleaned off, this would be obvious