Spin: generation, sensitivity and reception

Spin is the characteristic that separates table tennis from any other racket sport. A ball of two and a half grams turns at more than a hundred revolutions per second in a loaded loop at medium-high level, and that rotation commands the trajectory with an authority no other sporting ball allows. A dense topspin dives; a backspin refuses to rise; a sidespin deflects the ball in the air enough to surprise the best positioned receiver. The vocabulary of equipment turns, literally, around this phenomenon, and it is worth ordering it along the three axes the title states, because they are three distinct problems even though they arise from the same physics.

Generating spin is what the bat does when the player attacks. Section 1.3 explained the principle: the topsheet grips the ball through friction during the millisecond of contact, and the tangential displacement of the bat imparts rotation to it. What decides how much spin is generated is, in essence, the combination of three factors: the gripping capacity of the rubber, the time the ball remains in contact with the surface — the dwell time covered in 2.5 — and the fit between sponge hardness and arm strength. Each of those factors has its own section later in the book: the grip of the topsheet in 5.1, sponge hardness in 5.6. Here it is enough to retain that a high spin figure on the spec sheet does not guarantee much spin in practice, because that figure is obtained from a standardised stroke which may not coincide with that of the real player.

Being sensitive to spin is what happens to the bat when it receives a ball that already arrives loaded. The mechanism is the same as that of generation, but in reverse: the friction that allows rotation to be imparted is the same friction that forces the topsheet to react to someone else's rotation. A rubber that generates a lot of spin, by construction, suffers a lot from received spin. The most everyday example: a serve with backspin which, returned with a flat push on a gripping rubber, crashes into the net because the incoming rotation has closed the outgoing angle more than the player anticipated. Sensitivity is paid for in technical demand: the receiver must read the spin and correct the angle constantly.

That symmetry between generation and sensitivity is the central tension in choosing a rubber. Gripping inverted rubbers — the norm in attacking play — maximise both. Pimpled rubbers reduce sensitivity because point contact generates less friction; long pimples reduce it so much that they reverse the received spin. Anti-spin rubbers practically annul the interaction. Chapter 6 develops each type; what is relevant here is that the range of special rubbers exists, in large part, as an answer to this tension.

Receiving spin — returning it, transforming it, neutralising it — is the third axis, and already an operative one. A player can reverse the incoming rotation with an ascending loop, prolong it with a chop that exploits the received backspin, or try to annul it with a flat stroke or with insensitive equipment. Each strategy asks something different of the rubber and of the blade. The criteria for deciding which combination suits each style are addressed in chapters 7 and 11.

What the reader takes away is that spin is not an isolated quality one either has or lacks. It is a three-sided phenomenon coupled by the same physics of contact: whoever maximises generation takes on sensitivity, and the way reception is managed defines in large part the playing style and the equipment that accompanies it.