the aero advantage of a relaxed-geometry road bike may be exaggerated compared to a full-blown time trial bike, but drop bars do help with getting lower and out of a head wind compared to a flat bar at the same height.

now that last part is the tricky part because "road bike" and "hybrid bike" are two giant categories that include all sorts of different frame geometries, such that a very aggressive hybrid with a slammed stem and a flat bar would be more aero than the most relaxed geometry road bike with a raised stem, even on the drops. but in general, a drop bar will afford a couple extra inches of drop if the overal gemoetry and stem mounting height are in a similar ballpark.

take my two bikes below, a relaxed geometry road bike with stem mostly slammed, and a hybrid with stem mostly slammed. both bars have several inches of saddle to bar drop and allow me a decently aggressive aero postion when i'm on the hoods or the grips of the flat bar, but with the road bike i can get down even lower when i need to because of the drops. the bar ends on the hybrid can also stretch me out a little bit more for bad headwinds, but they're not quite as effective as drops.


my "go fast" fair-weather commuter: 2010 Motobecane le Champion SL Titanium













my foul-weather/winter commuter: 2011 Scott SUB 10 (alfine 8 IGH, hydraulic discs)






but again, it all comes down to the specific bike and its specific set-up. and yes, there are some fairly aggressive-geometry hybrids out there that allow for a pretty good aero position (i personally believe that style of bike is better referred to as a "flat-bar road bike", but that's just me)