Originally Posted by jcwitte
The rear cassette shouldn't be too worn. I bought the bike new last August and rode my other bikes through the winter. I have also been pretty good about cleaning and lubing the chain, and I replaced the chain well before the "chain checker" tool showed much wear. I'll check the rear derailleur adjustments and make sure everything there is good and then hope it goes away or at least doesn't get any worse. Otherwise I'll bring ask the LBS next time I'm in there.
I experienced the same grinding feeling when I changed my chain once. It wasn't so much grinding as a weird sort of "crunchy chain" sensation under load. My cassette was good, it turned out it was the chainrings. I had cleaned the chain regularly, and changed it as soon as the Parks chain tool indicated the first signs of chain stretch, but the 2 outer chainrings were toast anyway. They weren't cheap rings either, they were alu Specialite-TA rings, but apparently they were made of cheese-metal. The granny ring, a no-name steel 22T, was perfectly fine.