My bike is 10 years old. Some teeth on the crankset are worn. I figure I can replace this and the chain as well. I don't know about my capabilities of replacing the cassette, though. Can I just replace the crankset and chain, or do I have to change the cassette, too? It's Shimano STX (3*7).
I'm sure this has been asked before, still I would be grateful for some advice, as the cassette replacement would probably mean for me and my abilities taking it to a repair shop (despite books and websites).