The whole chain replacement thing is confusing to me. My LBS said every 1500 miles and said it was like an oil change on a car, preventative maintenance. But that seem excessive to me especially since my steel bike has the original chain and cassette from 1982 on it and I still ride it regularly and up until a month ago that was 30-50 miles a week (and more when I first got it because it was my only method of transportation for 4 years). Based on some of what I read I should not even be able to ride that bike and yet it rides just fine (doesn't climb all that well but that is more of a function of the gearing (6 speed cassette, standard crank) and the engine