Twist Weight

When a ball strikes the string bed off-centre — toward the sides of the frame — the racquet twists around its long axis. Twist weight (also called polar moment of inertia) measures the racquet's resistance to this twisting. It is the overlooked sibling of swing weight.

What Is Twist Weight?

Twist weight is the moment of inertia around the long axis of the racquet (the shaft). A higher twist weight means the racquet resists twisting more when the ball contacts away from the centreline.

Formula: I_twist = Σ mᵢ · rᵢ²

Same formula as swing weight, but rᵢ is now the perpendicular distance from the long axis — so weight at the 3 & 9 o'clock positions (widest point of the head) contributes most.

Typical values range from 12 to 18 kg·cm². This seems small compared to swing weight, but the effect on feel is significant.

Why It Matters

On a perfect centre-line hit, twist weight is irrelevant — the ball hits where the racquet is designed to be hit. But in real play, centre hits are the exception, not the rule.

• Low twist weight (< 14): Off-centre hits cause the frame to rotate, deflecting the ball and reducing power. The racquet can feel "unstable" or "hollow."
• High twist weight (> 16): Off-centre hits produce more consistent results. The racquet feels "solid" and forgiving on mishits.

Info: Twist weight is why a heavier, wider-headed racquet often feels more stable than a lighter, narrower one — even if their swing weights are similar.

Typical Values

| Twist Weight (kg·cm²) | Feel | Head Shape | |---|---|---| | < 13 | Unstable on mishits | Narrow oval head | | 13–15 | Average stability | Standard 100 sq in head | | 15–17 | Good stability | Wider or heavier head | | > 17 | Very stable | Oversize or heavily leaded |

How to Increase Twist Weight

Since twist weight depends on mass distributed laterally away from the long axis, weight added at 3 & 9 o'clock increases twist weight most efficiently. This is the primary reason players add lead tape at those positions.

Adding 2g at 3&9 (1g each side) can raise twist weight by roughly 1–1.5 kg·cm² — a meaningful improvement in stability without drastically affecting swing weight or balance.

Tip: If your racquet feels unstable or "mushy" on wide forehands and mishits, increasing twist weight is often more effective than increasing swing weight. Try 0.5–1g of lead at each of the 3 and 9 positions first.

Relationship to Swing Weight

Twist weight and swing weight are related but independent. Weight at 3 & 9 o'clock increases both, but the ratio of twist weight gain to swing weight gain is higher than weight added at 12 o'clock (which adds swing weight with almost no twist weight gain).

This is why Arcus considers both metrics when recommending customisation — optimising for one without the other gives an incomplete picture.