I've clocked myself at around 12mph. It's variable tho... I can't sustain that kind of speed for long right now. It seems to be slow for a road bike, but I'm on a commuterized mountain bike, so I'm ok with being slow.

Most of the time I don't worry about speed since I ride by myself. I'd rather worry about am I keeping a good cadence, am I pushing my gearing just enough, or am I pushing distance a reasonable amount. Those are easier for me to judge since I don't have a cyclocomputer.