Some remarks about the interrelationship of drop bars, bad backs, aerodynamics and centre of aerodynamic pressure inspired by discussion in
Calculating saddle & handlebar position, but a bit off-topic there.
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What gives cyclists bad backs is contorting themselves to fit bicycles carelessly "designed" to follow an obsolete fashion. Drop bars might offer more efficient locomotion -- I'm not so sure about that, actually -- but they can't ever be good for your back (unless your "vertebrae have fused in the drop bar position" as a Melbourne physio used to say). Skinny tyres might be good for racing but they can't ever be good for your back. High pressure tyres may or may not look "fast" but generally speaking balloons actually have less rolling resistance and don't ruin your back like high-pressure tyres.
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I'm totally unimpressed with the argument that a flat back on the drops somehow gives a cyclist greater speed by better aerodynamics. Aerodynamics work through CdA, the aerodynamic coefficient of the moving body Cd multiplied by its frontal area A -- and the human body is grossly aerodynamically inefficient, and so is a bicycle for that matter. But mostly the myth lives on because old motor racers rarely take up cycling, and old cyclists rarely take up motor racing. See, motor racers know, by comparing timed laps with different wings, that you have to be travelling around 100mph before aerodynamics make much of a difference. To state the obvious, cyclists rarely travel at 100mph.
Just for the sake of completion, sure, it is possible to make a bike aerodynamic, and to make the rider more aerodynamic with tight-fitting lycra and a helmet that will take his coach's eye out with its spiked point (which would do a lot better cut off short according to Professor Kamm's formula than remaining as the fashionable full length point), but you wouldn't be able to tour on a bike with disc wheels rather than spokes, and with the triangles filled in -- where I live, on an aerodynamic bike you'd come a cropper before fifty paces from my house when the wind coming all the way from the Urals up the river valley crosses your path at right angles, and that's before you even come to the footbridge across the river, one of my favourite crossing points.
There's something else old motor racers and car designers know that bicyclists and their associated designers apparently never heard of: A flat back on the drops moves the aerodynamic centre of pressure forward, adding to the instability of the bike. The rider must put more effort into keeping the bike running straight. The tyres work harder because the forward CoP (centre of pressure) makes unwanted steering inputs that the rider fights. That by itself might be enough to chew up the marginal advantage of drops in power delivery and perhaps another marginal aero-advantage in a flat back. The CoP works perceptibly from a much, much lower speed than aerodynamics do, and the better the CoP (meaning further back), the greater the aero advantage it brings with it because it brings because there is less space behind the rider for the newly unlaminated air flow to cause drag, that is, the most energy-sapping disturbed airflow is off the back of the bike sooner. Not that there's a lot of airflow clinging to a human: his body's various roundings are all hostile to laminar airflow in any direction except maybe -- I know it is counter-intuitive but so is a lot of proven aerodynamic theory and practice -- feet first.
Aerodynamic improvements on bikes can never be anything but marginal, and on touring bikes they're likely counterproductive. Thus there is very little reason to set up a non-racing bike for drops, and less to design it to take drops, except if the individual cyclist has ridden so long on drops that it would be too much of an effort to learn a new riding style, in which case the cyclist should of course be given what he wants -- it's his money.
