Pole vault flex number measures the stiffness of a pole within its weight rating. Lower flex number = stiffer pole (less deflection under standard load); higher flex = softer pole. Two poles with the same length and weight rating (e.g., 14 ft, 145 lb) can have different flex numbers (e.g., 13.0 vs 14.5) and feel different at takeoff. Typical flex range is 10-30.
Manufacturers measure flex by suspending the pole between two supports and applying a standard load (typically 50 lb) at the center. The deflection in inches becomes the flex number. Lower deflection = stiffer pole = lower flex number.
Manufacturing tolerances mean two poles with identical length and rating can vary by 2-3 flex points. Coaches use flex to fine-tune within a vaulter's rating range as approach speed and technique develop.
Vaulters often move through 2-3 flex numbers within a single weight rating before stepping up to the next rating. Coaches log flex against video to track which feels and performs best.
For beginners, flex is less important than length and rating. For developing and elite vaulters, flex becomes a fine-tune. AI form check measures bend pattern and pit-landing zone so you can quantify how each flex change affects performance.
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