Originally Posted by
duke_of_hazard
If my top speed on the Dahon on a flat road with no wind is 25 mph, how fast can I go on a decent road bike?
25 MPH is a pretty decent speed, depending on whether that is a 100 yard sprint, a couple of miles, or the entire ride.
Perhaps find someone who will loan you a nice road bike, or perhaps rent one for a few days.