I do need to figure out how to make cassettes last longer, as I just replaced this one a year ago, along with the chain. Each had about 4200 miles on them. I probably left the chain on too long, so that after it became worn, it wore down the cassette as well. I was under the impression that you should only need to replace the cassette every other time you replace the chain. I probably should also use the big chain-ring more, since then I would use the larger cogs in back and have less wear there. I'm currently doing that on the worn cassette now.[/QUOTE]

Well, I seem to have to replace mine every 2 or 3 years. On the other hand, I never have to replace the one on my wife's bike (well, not in 10 years). As far as I can see, the significant difference is that she has a chainguard, which keeps all the rubbish off. I am going to fit one on my bike next time I do a refit.