I was just looking around Cycleops site and found power charts for their repected trainers. The magneto (which i'm training with)requires the rider to displace 200 watts to maintain 15mph. To maintain 18mph requires the rider to displace approx 300 watts. Minus all the obvious variables that make road riding more complicated than riding on a trainer, do those power outputs seem accurate with real world speeds. To me 300 watts to maintain 18mph seems high.