How long should, say, an Ultegra 12-27 cassette last? IIRC, it's on its second chain and is skipping a bit, after a total of, oh, say 4000-4500 miles. I clean and lube the chain fairly regularly. The chainrings have been on the bike forever.
I have a fresh chain and cassette on the way... just wondering if there's any hope for keeping the old stuff on any longer. Ultegra cassettes aren't cheap!