Originally Posted by caloso

The reason I ask is that the position of your hands has a huge effect on the position of your torso and thus a huge effect on your aerodynamics. If you have your hands on the returns (and by returns I mean the straight parts that point to the rear of the bike), your elbows tend to be straight and your torso up, so you catch a lot of wind in your chest. If your hands are deep in the curves, you'll have to bend your elbows to keep from banging your wrists on the undersides of the bars. Bending your elbows brings your chest down, making you more aero. It also makes it a lot easier to shift and brake.