In my case, it was so much like riding a bicycle that it was nearly indistinguishable from the real thing. I just got back from a "see if I can do this without killing myself" ride on the new bike, since I haven't ridden one in a decade. I can, but it wasn't pretty... and I'm not just talking about my ass on the seat.
I seem to remember that when I was a kid you could reach the ground while sitting on a bicycle seat. Am I misremembering? In any case, the starting then sitting down thing was really weird, and it took a bit to get used to having to get off the seat when I stopped, but I never quite fell over. I only once tried to grab for the nonexistent clutch.
Since I have a handlebar mount for the GPS, I know precisely how far, how fast, how long I rode. Let's just say that Lance Armstrong isn't quaking in his pedals.