What is the 4-to-1 rule?

• A. If A Rope Is Bent Around An Object At Least Four Times Its Diameter There Will Be No Loss Of Efficiency Due To Bending
• B. The Rope Should Be Four Times As Long As Its Diameter
• C. Bending More Than Four Times Reduces Strength By Twenty-Five Percent
• D. Only Applies To Certain Rope Materials

Answer: (A)

The 4-to-1 rule is a guideline for how tightly a rope should bend around an object to avoid weakening it from bending. When a rope is bent too sharply, the fibers experience micro-bends and concentrated stress, which can cause energy loss and wear. By ensuring the bend radius is at least four times the rope’s diameter, you keep the rope bending gentle enough that bending-related losses are minimized and the rope behaves more like a straight pull.

The other statements mix up the meaning of the rule: it’s about bend radius, not a length-to-diameter ratio; it isn’t a fixed claim that bending more than four times reduces strength by a specific amount like 25%; and it isn’t limited to certain materials.