Originally Posted by
flyboyfish
I think what I will do is go for new chains for both bikes and see how the shifting goes. If shifting is still jumpy, then I'll get new cassettes as needed at that point.
And once you get new cassettes, if you wanna ~double your cassette life, get two chains to go with it, and rotate between the two every 500-1000 miles. This requires the chain to have "a chain link" on it of course, which most now do. Something like this:
http://www.amazon.com/KMC-MISSING-Bi.../dp/B001PTA4I8