Starfish - I think I'm already noticing this phenomena as well! When I first started riding, I was mostly doing the flat bike trail in Sacramento. I stayed in my middle ring and the one noticeable hill was not very fun. But when I was down there riding a couple of weekends ago, I stayed in my big ring the entire ride and I hardly noticed the "hill". My average wasn't very fast though...I was riding with a friend and we were too busy talking to pay much attention to speed. But I know I could go a heck of a lot faster on that trail than I could've a few months ago.

BTW, I'm at 422 miles and approx. 25,600' of climbing for the month so far. This is a lot for little old me!