I have 4200 miles on my dura ace chain with almost zero wear and 4100 on my other bike's 105 with zero wear. I use to worry I should change the chain but frankly I clean it and lube it, do not ride in the rain, and normally spin. I keep hearing of those going thru chains in 1500-2000 miles and wonder? Maybe I just cannot generate any power riding but I pretty steady and quick in the long haul for a old guy.