Are you counting warm up, cool down and rest intervals in that hour? I guess you don't do one legged drills either.

This morning's workout was Spinervals Ultra Core Conditioning. It alternates between one legged drills/ off the bike core work and high cadence spins/ core work. In 66 minutes you're off the bike for about 20 minutes and there is a warm up and cool down period. My speed sensor gives me 9.4 miles for this type of workout.

V.