Get Outdoors - Mountaineering Basics: Applying Friction: Breaking Hand

Except for one device (the Grigri, discussed later), the braking hand produces the initial force by the friction of the belayer's hand gripping the rope. In any belay method, the rope from the climber goes around or through some friction-producing element (the belayer's hips, a specialized device, or a Munter hitch knot on a carabiner) and then to the belayer's braking hand.What kind of force can the belayer's breaking hand exert?

Because everything starts with the belayer's grip, we should consider what kind of force it can exert before looking at specific devices and methods. In fact, considering its importance, remarkably little is known about what kind of stopping force a belayer's hand can exert when in a braking position. From what little testing has been done, and from the common experience of climbers, a few tentative conclusions may be made.

The average amount of force that can be exerted by a person's grip is probably something under 50 lbs., whether the rope is running through the hand or being held statically.
The variation from one person to another is large and cannot be predicted from obvious physical characteristics (such as weight, size, and muscle mass); some adults can exert a force of only about 10 lbs. of force, others as much as 90.
The position of hand and arm relative to the direction of pull is significant: the strongest position is with he rope pulling from the little-finger side of the hand to the thumb-forefinger side with the forearm roughly parallel with the direction of pull.
Bare hands can generally exert more force than gloved hands, though the texture and thickness of the glove probably make a difference (thinner and rougher is stronger).
You can exert more force with larger-diameter ropes.
Choice of hand appears to be insignificant.

Given the great variation among people, the beginner would do well to take part in some weight-drop tests, attempting to hold falls of a dead weight, using various belay methods. This can give you a rough idea of whether you are at least near average in your ability to stop a fall.