Yeah, it does take 2cm or so off the effective "grip width" of each half of the handle bar (where you place your hands). I'm biking for comfort/recreation/pleasure/exercise, and aerodynamics isn't in my list of priorities. In theory, the less aerodynamic I am, the more exercise I get. Ha! My riding position is upright enough, and I often have enough other drag on my bike (pannier racks and sometimes bags), that the position of my grip won't matter there anyway.