Tennis string tension explained

What tension actually does

A string bed stores and returns energy when the ball deforms it. At lower tension the bed deforms further, holds the ball fractionally longer, and returns more energy — more power, higher launch, longer dwell, more comfort. At higher tension it deforms less and returns less, which reads as control.

The spin row surprises people. Lower tension lets the main strings move further sideways and snap back further, which is the mechanism behind topspin — so the old belief that tight strings produce spin has it backward.

Where to start

Every frame has a recommended range printed inside the hoop. The Wilson Clash 100 v3's, for instance, is 47 to 57 lb with an optimum of 55. Start in the middle of yours, play three or four sessions, then adjust.

• Balls landing long — go up 2-4 lb.
• Balls landing short — go down 2-4 lb.
• Arm discomfort — go down 4-6 lb, and consider changing string type.
• Bed feels dead and unresponsive — this is usually age, not tension. Restring.

String type changes the right tension

This is the part most club players do not know, and it causes more bad string jobs than anything else. Polyester is significantly stiffer than multifilament at the same tension, so it is normally strung several pounds lower.

A player who has been using multifilament at 55 lb and switches to polyester at 55 lb ends up with a bed that is both harsher and lower-powered than they expected — and frequently concludes that polyester is terrible, when what was terrible was the tension choice.

In a hybrid setup the mains and crosses are usually strung at different tensions too, with the polyester mains a few pounds below the softer crosses. Any competent stringer will do this by default; it is worth confirming.

Tension loss, which is the real story

Strings begin losing tension the moment they come off the machine, and they keep losing it whether or not you play. Polyester loses a substantial fraction within the first few hours of play and continues falling; multifilament and synthetic gut lose tension more gradually.

The practical consequence is that most club players spend most of their time on a bed several pounds below what they asked for, and adjust their swing to compensate without noticing. That is why restringing on a schedule rather than on breakage is the single most noticeable upgrade available to a regular player.

The rule of thumb: restring as many times a year as you play in a week. On polyester, every six to eight weeks regardless of breakage.

Things that do not work

• Stringing outside the recommended range. The range exists because the frame is designed for those loads. Going well above can damage the hoop; going well below produces an unstable bed.
• Chasing tension to fix technique. If your misses are long only when you go for it, that is timing, and no tension change will address it.
• Stringing tight for spin. It is backward — lower tension lets the mains move and snap back more.
• Ignoring the string type. Tension numbers are not comparable across types; 55 lb of poly and 55 lb of multifilament are different beds.