It's an interesting subject. I wonder what the drag coefficient of a traditional cycling cape is? My main baggage for day trips is a rack bag which isn't discussed but I reckon should have minimal impact on aerodynamic drag. My AHS handlebars let me adopt a slighly lower drag body position when needed but, as I found out only a couple of years ago, drop bars are too uncomfortable.
The biggest factor in the formula is V because it is squared, but it's actually not the bike speed but the effective speed after taking account of the head or tail wind. Cycling at 15 mph into a 15 mph wind results in the drag losses increasing by a factor of four while the 15 mph tailwind reduces, in theory, the drag losses to zero. Crosswinds and associated turbulance also cause extra drag and I suspect that baggage configurations which reduce the head wind losses then increase the crosswind losses. Cycling is much more pleasant on a calm day as the extra effort needed to fight a headwind is never fully compensated by the reduction in effort when there's a tailwind.
