re: 60 MPH...achieveable? Who cares?!? Let blueprint an engine!
Cd is .9 for a bicycle and rider, with the rider sitting upright... Cd is .5-.7 with the rider in a tucked postition.
DV weighs 150lbs...figuring on the extreme high side, let's say the bike ends up weighing 60lbs. for a total of 210lbs.
In a tucked position the frontal area will be nowhere near 6 Sq. Ft. A small fairing would reduce this area to nearly 1/2, or 3-4 Sq. Ft. I think somewhere around 5 H.P. will do it.