Chains and sprockets are wearable items. If the chain is not properly cleaned and lubricated, it can cause premature chain and sprocket wear.
When washing your bike, put it on the stand so you can turn the wheel and clean every part of the chain. Lubricate the chain immediately after cleaning. I prefer a good quality sticky lube to the one that splatters all over the place! BelRay Blue Tac Chain Lube is my go-to. Once you have a clean bike, check the condition of the chain and sprocket. The condition of the sprocket can be checked visually by looking at the sprocket teeth. The teeth are hooked when worn, and shortened and rounded due to neglected maintenance in severe cases. The condition of the chain can be checked by placing the bike on the stand. Turn the rear wheel and visually check the condition of the chain. Feel for tight spots or sticky links in the chain as you spin. Try pulling the chain away from the last part of the rear sprocket. If the chain can pull half a sprocket or more off the rear sprocket, it's time to replace it. If the chain moves significantly from side to side when the zipper chain is pushed over the sprocket, wear has occurred.
So, you need a new chain and sprockets.
