Rappelling in rugged rock terrain

One hand must always (!) hold the rope beneath the rappel device while rappelling. The other hand only provides additional stability, whether by gripping the upper part of the rope, or against the rock (pressing and correcting the direction of rappelling). It is important to work with the legs in order to maintain balance and postural stability; slightly bending your legs provides stability against swinging to the side. (Video from e-book Mountaineering Methodology, www.mountaineeringmethodology.com)