I too have been riding a mtn.-type bike. Actually a "comfort bike". When I tried to do a 100k ride with my sister, she insisted that I would need slicks. She was right. They helped a lot. Then yesterday I test rode a bike with bigger and narrower wheels. Wow! What a feeling! Suddenly I was doing ... well, I didn't have a bike computer on so I don't know how fast I was going, but it definitely a lot more than 10mph in spite of putting in less effort. But no need for speed envy yet. Here's the up side to riding a mountain bike even though you want to go fast: As you train on a mtn bike you will nevertheless pick up speed on the road, and you will be WAYYYY fast when you land that dream job and can afford a road bike. Meanwhile, you'll have fallen in love with the mt. bike, but you could keep her for riding on park trails, doing the shopping, working out ...