Stick your arms straight out in front of you with hands positioned like you're gripping your narrow flat bars. Then either pull your hands toward you or lean forward by bending your elbows downwards. Make sure your palms stay parallel to the floor. Not so easy is it? If you're like me, your thumbs will want to rotate upwards.

No try the same thing with your palms perpendicular to the floor like they would be in the hoods or the drops. See what I mean?

Mountain bikers don't have their hands straight in front of them, they're farther out to the sides because their bars are wider.