The bend radius of fiber cables is critical for maintaining high performance and longevity. During installation under tension, maintain a minimum bend radius of 20 times the cable's outer diameter, while post-installation requires a minimum long-term bend radius of 10 times the. Fiber optic cable bend radius is a critical mechanical parameter that determines how sharply a cable can be bent without risking microbending, macrobending, signal loss, or long-term structural fatigue. It is measured from the inside of the bend, not the outer curve. For example, if a cable has an.