Deflection Board Testing, Explained

A deflection board is a simple piece of equipment in concept: a clamp holds the butt end of a shaft rigid, a fixed weight hangs at a set distance from the tip, and a gauge measures exactly how far the tip drops under that load. What it produces is a repeatable, comparable number — something a manufacturer's flex letter, by itself, was never designed to be.

Why Flex Letters Aren't Standardized

There's no industry-wide governing body that defines exactly how stiff a "Stiff" shaft has to be. Each manufacturer sets its own internal standard, which means a Stiff shaft from one brand can measure noticeably closer to another brand's Regular offering. Deflection testing sidesteps this entirely by measuring the physical bend directly, brand label aside.

What We Measure Beyond a Single Number

Rather than a single overall flex reading, we log deflection at three points — tip, mid-section, and butt — because two shafts can share an identical overall deflection number while bending in completely different patterns along their length. A shaft that's stiff at the butt but soft at the tip will feel and perform differently than one that's uniformly stiff throughout, even if their single-point deflection readings matched.

The board doesn't care what's printed on the shaft. It only reports how far the tip actually moved under a known load.

How Long a Reading Takes

A single shaft reading takes under two minutes once it's clamped in. During a fitting session, we typically run three to five candidate shafts across the board before narrowing to the one or two that get demo-tested against your swing on the launch bay.

What It Can't Tell You

Deflection testing measures the shaft in isolation — it doesn't capture how you personally load and release it. That's why board readings always get paired with your logged swing data before a final recommendation, rather than used as a standalone answer.