I gots 42 and 52 up front, my back door is a six pack running from 11 to 23, and I never leave that 42 except on descents. I usually run on the 42 and 16 teeth for most of my rides, shifting a little, but not as much as I should be. I attribute this to my previous occupation as a courier, and years of riding a fixed gear in that same set up. Also, I am really lazy, and shifting sometimes seems like work. It's pretty flat where I live, so that might be a factor.