The frame and fork are designed for optimum aerodynamics when traveling in a straight line. Consequently, the fork will be wider at it's leading edge and taper to where it meets the frame. When the fork is turned far enough, the wider section will contact the frame, but normally this limit wouldn't be reached even at the turn around of a triathlon bicycle course. IMO, it's a very minor drawback for having an aerodynamically efficient bicycle. Anybody who rode during the days of down tube shift levers will be well aware of the chips on the side of the down tube, caused by the front brake caliper's barrel adjuster (even when they had a rubber bumper), when you let the wheel flop too far. Nobody complained about it being a design deficiency.