Originally Posted by
joonoo
...I try to ride vigorously, before I start sweating (I sweat a lot), and I was never passed by other cylcer than on roadbike. Now it makes me want to purchase an entry level roadbike that is setup up properly for me. ...
Yep, that's why I first got a road bike. Not so much questioning are the road bike riders really faster than I am, but why not be as fast as your own potential?
Honestly though, the speed advantages for road bikes mainly lie in the wheels and tires, and in the aerodynamics of the rider position, and to a lesser extent less weight. From that base we wouldn't be wrong to say you can get close to the same speeds by changing the wheels, tires and rider position on a mountain bike to emulate that of a typical road bike. For a low end mountain bike only weight is the real downfall.
By the same token, unless it's an advanced cyclist he won't see much speed gain from the road bike.