I would like to know, what are your favorite brand rear sprockets? I don't remember if I ever changed my rear sprocket or not. I only change what is bad unless there is significant wear on any of the other components. So far with 43000 miles, 2 front sprockets, 3 chains, rear sprocket 1 or 2 but I don't think I ever changed the rear. I may go ahead and change both sprockets this time, my o ring chain is not that old. The chain trick is to get the highest tensile strength you can find in the size that fits your bike. I found a chain that will handle 1000cc and I put that chain on my 600. No chain adjustment many miles later, works great.