Hello, It's time to buy a new chain. I bought a PC-971 chain and to my dismay, it's only lasted 800-900 miles and it's already stretched halfway to the .16'' mark. How much longer do you think my chain can last before I have to replace it? This time around I'm probably going to buy the cheaper PC-951, but I'm wondering what the difference is. The specs say it's made of steel, so does it last longer than the nickel plated 971 and 991? Furthermore, WHY does the 991 cost $45? EDIT: Also, this is my first time using a 9-speed system. Previously I've been riding on an 8-speed, and the current chain on the 8-speed shows no signs of stretch after 2200 miles. Do the thicker 8-speed chains last longer than the thinner 9-speed chains? I guess I shouldn't complain though, I spend a lot less on my 9 speed than your 10 speed.