I don't know about this....I started out on a Specialized Crosstrail (a hybrid) when I was 26 after not having ridden a bike since I was around 12 or so. 3 months later, having become addicted, I bought a Madone 4.5 and I'm pretty sure my speed did increase from the 15ish MPH range to 18ish almost immediately. Of course, when I started doing longer rides and more climbing, it went back down a bit, but there is a definite increase in speed going from a hybrid to an actual road bike, IMO.