For dynamic belay systems, what is the minimum diameter for a rope passing over a fitting?

For dynamic belay systems, what is the minimum diameter for a rope passing over a fitting?

• A. 8 mm
• B. 12 mm
• C. 16 mm
• D. 10 mm

Answer: (B)

When a rope passes over a fitting in a dynamic belay system, its diameter at that contact point matters because it affects wear, edge loading, and how smoothly the rope moves through the hardware. A rope that is thick enough resists pinching and abrasion at the fitting, distributes pressure more evenly, and minimizes the risk of damage under dynamic loading. This is why a minimum diameter of 12 mm is recommended: it reduces the chance of excessive wear or cutting at the contact point and maintains reliable performance with typical belay hardware. Smaller diameters can be more easily damaged or squeezed by the fitting, while much larger ropes add unnecessary weight and stiffness without giving extra safety in this context. Therefore, 12 mm is the appropriate minimum.

When a rope passes over a fitting in a dynamic belay system, its diameter at that contact point matters because it affects wear, edge loading, and how smoothly the rope moves through the hardware. A rope that is thick enough resists pinching and abrasion at the fitting, distributes pressure more evenly, and minimizes the risk of damage under dynamic loading. This is why a minimum diameter of 12 mm is recommended: it reduces the chance of excessive wear or cutting at the contact point and maintains reliable performance with typical belay hardware. Smaller diameters can be more easily damaged or squeezed by the fitting, while much larger ropes add unnecessary weight and stiffness without giving extra safety in this context. Therefore, 12 mm is the appropriate minimum.