On Saturday, December 22, 2018 at 12:52:51 AM UTC+1, Andre Jute wrote:
On Friday, December 21, 2018 at 8:25:37 PM UTC, wrote:
At low speeds - those below 100 mph of so, aerodynamic drag really isn't a large loss unless you're playing for real small power such as that developed by a human over relatively long periods of time.

Just as a demonstration.

30 square feet of frontal area
coefficient of drag of 0.5
This is similar to a family car

F = 0.5 C ρ A V^2

A = Reference area as (see figures above), m2.
C = Drag coefficient (see figures above), unitless.
F = Drag force, N.
V = Velocity, m/s.
ρ = Density of fluid (liquid or gas), kg/m3. (dry air at 70 degrees F ~ 1.2)

.5 x .5 x 1.2 x 30 x 27 m/s (60 mph) = 243 N
.5 x .5 x 1.2 x 30 x 45 m/s (100 mph) = 337 N


Whereas the power to accelerate the mass of a car which is about 2200 lbs is huge. KE = ½mv²

Thanks for putting the numbers to my argument, Tom.

Andre Jute
DESIGNING AND BUILDING SPECIAL CARS; Batsford, London; Bentley, Boston

I just reading an aero special article in TOUR magazin. Position on the bike can save you 54 watts or gaining 3.9 km/hr going from riding on the tops to riding in the drops. Clothes can make a difference of up to 27 Watt or gaining 2,3 km/hr in speed. An aero bike saves you 16 Watt or gaining 1.4 km/hr. This is all at a speed of 35 km/r, a speed not unrealistic for a lot of us. So putting some estimated numbers in a formula doesn't do the trick IMO.

Lou