This thread's been really helpful for me, too, although when I try to apply it while on my bike, my brain goes ka-phooey. It all seems bass-ackwards to me - or at least mutually inconsistent - on the front chainring, bigger is harder, but on the rear cog, bigger is easier. For the time being I'm still relying on the nice little numbers on my shifters, where a little number always means easier (which I have to admit is usually my goal, given my beginner's fitness level!)