This is how you are supposed to achieve the rough size of drop bars on road bikes - you can then go wider / narrower for comfort & leverage / aerodynamics.

Typically, with your upper body relaxed, have someone measure the widest points between the bones in the outer shoulder (NB: measure straight, don't lay the tape across the shoulders) - this is the (rough) measure of the centre-centre dimensions of your bars. Track riders often go down in size for some reason, not quite sure (beyond aero'd's)

Olly