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Racquet Science: The Inch That Changed Everything

Monday, May 21, 2012 /by

Racquet Science expounds on the surprising realities of what actually happens when ball meets racquet—and how this knowledge can improve your game. Today, we take a look at how the advent of composite frames has contributed to today’s spin- and pace-heavy play.

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ShriverAt the 1978 U.S. Open, Pam Shriver became the first player to play a Grand Slam final with an oversized racquet, namely the 110-square-inch Prince Classic. Though she lost the match to still-wood-wielding Chris Evert, Shriver’s performance with the aluminum frame despoiled the woody in many eyes, setting the stage for the emergence of game-changing racquet technologies. As Stephen Tignor explains in High Strung: Bjorn Borg, John McEnroe, and the Untold Story of Tennis’s Fiercest Rivalry, “[Shriver’s] frame had been manufactured two years earlier, but it had been widely derided among recreational players as a ‘cheater’s racquet.’ Once Shriver legitimized it, the floodgates were open.”

By the end of the 1980s, the “preposterously small wooden racquets” of yesteryear had been replaced en masse “by a wave of bigger, more explosive, atomically manipulated frames” made from graphite- and carbon-based composites. Before long, Tignor continues, “players were hitting with power and spin that would have been unimaginable just 10 years earlier.”

So what exactly changed? How did racquets manufactured with new materials enable players to hit with so much more pop and spin? The generally accepted narrative is that modern frames return more energy to the ball, and thus allow for greater power—“rather like,” in the words of David Foster Wallace, “aluminum baseball bats as opposed to good old lumber.” Hence, the story goes, today’s prevalence of Samprasian serves and booming ground strokes: The racquets are supercharged.

But this explanation, while not wholly untrue, is flawed. Indeed, due to their added stiffness, graphite frames are much more lively than their wooden counterparts. (Newer frames permit decent pace even on balls struck outside of the stringbed’s center, which was less common in the old days; balls hit off the tip of a woody simply died.) Yet, it’s not so much a disparity in energy transfer that separates old sticks (and games) from the new, as much as a difference in head size. As Wallace duly notes, in “Roger Federer as Religious Experience,” “The truth is that, at the same tensile strength, carbon-based composites are lighter than wood, and this allows modern rackets to be a couple ounces lighter and at least an inch wider across the face than the vintage Kramer and Maxply. It’s the width of the face that’s vital. A wider face means there’s more total string area, which means the sweet spot’s bigger.”

This extra inch of frame width—10 inches, say, as opposed to the wooden nine—ultimately leads to more spin- and pace-friendly racquets. Why? What’s the big deal about wider frames? Perhaps unsurprisingly, the answer has everything to do with topspin.

Bracketing the question of polyester strings and “snap-back” effects, there are, to speak somewhat reductively, three different ways that players can manipulate racquets to impart more topspin onto the ball. The first is simply hitting the ball harder. “Suppose the racquet head slides across the back of the ball at 10 mph,” Rod Cross and Crawford Lindsey explain, in Technical Tennis. “The ball will start to rotate if it wasn’t already spinning, and it will continue to rotate faster until the back of the ball is also traveling at 10 mph. At that point sliding stops and the strings grip the ball,” preventing it from spinning faster. Upon leaving the strings after impact, the back of the ball will be spinning faster than the middle of the ball, yielding 22 revolutions/second, or 1,320 rpm. If the ball is hit harder, it will naturally spin faster. “At 20 mph the ball will spin at 44 revolutions/second,” Cross and Lindsey estimate. “At 40 mph the spin will be 88 revolutions/second.”

The second way that players can use their racquets to put more English on the ball is by swinging with an angled stroke. Brushing upwards on the ball at a steeper angle—to hit, say, a topspin lob—will cause the ball to slide across the strings, spin faster upon leaving them, and clear the net with a greater margin.

And finally, the third way is to tilt the racquet face, such that the stringbed is not facing the net but instead angled toward it. “That is equivalent to having the ball approach the strings at an angle farther from a right angle path,” Crawford and Lindsey say, which, just like brushing up at a steeper angle, causes the ball to slide against the strings and turn over on itself. 

Today’s more forgiving racquets (wider than wood by at least an inch, recall) enable players to do all three of these things—swing hard, brush upwards on the ball, and tilt the racquet face—without having the ball clip the frame. But the narrowness of wooden racquets made it tough. As Crawford and Lindsey explain, “Players used topspin and backspin in the old days, but the amount of spin was limited by the fact that the racquet head needed to remain vertical as they swung the racquet head upward for topspin or downward for backspin…By keeping the head vertical, the sliding distance of the ball across the strings [upon impact] was kept to a minimum, which also helped to keep the ball away from the edge of the frame.”

The final calculus is that wider frames, which allow for an inch (or more) of potential ball-string sliding distance, can augment spin production by four (or more) times. The rest of the story then falls into place. Able to generate more topspin without mishitting, players have been able to swing faster and hit the ball harder without fear of spraying the ball long or wide. And swinging faster, in turn, has allowed players to generate more topspin…which has enabled players to swing even faster and hit even harder. The arms race continues today and, as new technologies continue to emerge onto the scene, it shows no sign of abating.

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CORRECTION: It was indeed the Prince Classic. My mistake. And yes, I meant abating instead of abetting. Thanks for reading.

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