Slow. On long solo rides, I tend to be pokey. Ironically, when I get tired, I push myself more because I am so eager to get home! Generally, however, I need other people to chase, overtake and pull now and then. I can't even imagine doing a time trial.

edit: By slow, I mean slow - under 15 mph, but with nominal stops. For urban century earlier this month, I took it easy, got lots of snack along the way, and what with hundreds of stop signs and stop lights and a few staircases along the way, 120 miles (including ride to and from start) took ten hours!