I just have to tell y'all that a new chain does indeed make a difference. I have put about 2300 miles on my Trek Pilot 5.0 since I got it in March. I've often read that you should replace a chain every 1000 miles. I kept thinking, why? It seems fine to me. Well, I did it anyway and wow! It shifts smoothly again (I really hadn't noticed that it wasn't--you know--one of those gradual things). Soooo--change those chains out!!!!