Vincent Leroux

The ratio between a racquet's gravitational moment and its inertia. The formula, one worked example, what four grams do to it depending on where they go — and the three things it does not say.

Not two qualities, two structures. What each one does to the ball, to the arm and to the life of the string — and why the player who never breaks is often the worst served.

A ball never meets a string at its stringing tension. The model, the equations and the figures: what string-bed deflection adds in kilos, and why a stiff string takes more of it.