it is doable for a fit person. His Faro has thin hard Marathon tyres, rigid fork, straight bars meaning efficient with air resistance. It can easily be just as efficient as a Bosch bike, 6WH per mile, 120WH for 20 easy miles not much traffic lights, 40% of the battery's capacity, 3 bars out of 5 left.If your bike weighs under 15kg, you have the 8Ah 288wh battery. You come back with 3 bars on the meter so that would be about 120wh of use. 20 miles at an average 15.5 mph would take 1.3 hrs so to use 120wh from the battery. In that time, you were therefore drawing an average of 93w from the battery, but your system is only about 70% efficient, so you got an average 65 watts of assistance.