Train on an mtb with super aggressive knobby tires through the winter, then when you switch to the road bike in the spring you will be amazed how much easier it is to crank out higher speeds.

I'm glad carpediem mentioned slow days. Some people don't get the best results from pushing their bodies that hard constantly and mixing in a few recovery ride days into your training can help. Check out the other threads on this by people who have had success with it...