Ask any old school pro about improving technique and they will tell you to ride a fixed gear bike. This tradition continues today (have you seen those VC boys lately). Almost all the Pros spend their first few months of training on a fixed gear bike. Benefits of fixed gear training:
Develop a faster, smoother spin
Increase your power
Focus on technique not speed
A fixed gear bike forces you to pedal constantly. You may think you do now, but your first ride will show you reality. There is no freewheel so you can't coast. You can't coast when you start or stop. You can't coast and get off the saddle over a pothole. You can't coast when you crest the top of a climb. You can't lift your inside pedal and coast around a corner. And the biggest thing is that you can't coast downhill. In fact, you will spin your ass off downhill to the point that you lose control!