Yes, I usually average 19 - 20pmh on my rides. They're mostly flat though. Sometimes I've tried to go slow, like the day after a hard ride, but my body and my bike seem to be most comfortable at 20mph. I also really only use 1 gear and never shift (unless I'm going up or downhill or trying to catch someone).

I've been eyeing the Surly Crosscheck. I'm trying to tell my wife that I NEED it, and that I won't be getting rid of either of my other bikes. She's not going for it. I guess she'll learn to live with it when (if) it comes home :-) I've also thought of making the Mamba into SS or Fixed gear, since I only use the one speed, but I really don't want to put that much money into such an old bike. Especially since it isn't the right size. It's a 15.5" frame and I'm 5'10". The Mamba actually fits my wife pretty good, but she doesn't ride. Maybe I'll make her ride, then I'll only have 2 bikes and she'll have 1.