Hey everyone I have some questions I'd like to ask about bicycles before I get real serious about buying a new one. First off, what kind of difference in speed is there between a 30lb mountain bike with smooth tires and a road bike that is between 1/2-2/3 the mass? I ask because I currently ride a Specialized Hard Rock Pro 2 2004 with smooth tires and I can typically average between 16 and 18 mph with no problem. I am interested in getting into racing and I am wondering what kind of speed increase I can expect from buying a road bike rather than a mountain bike of similar price. I have not spent much time on a road bike before, just when I tried out a Cannondale at the local bike shop--it seemed to have a much higher acceleration and top speed although I could not be certain as it did not have a cycling computer like my commuter.
Anyway, I weigh appr. 150 lbs and I am about 5'9" tall. I am willing to spend between $1000 - $1500 on a bicycle that will stand up to several thousand miles of casual riding per year plus more if I do decide to start racing. Considering my needs, would it be worth it to buy a road bike or would that not give me any significant additional speed? Whatever advice anyone can offer me would be greatly appreciated, thanks.