Inside Roger's racket science

Ho-hum, Roger Federer made another year-end championships final. In other news, pigs dig mud, sword swallowing is dangerous and, apparently, winter likes to whack Buffalo. Some things never change. But for Federer, who has reached a record-tying nine of these prestigious finales, it's what happened just before he had a chance to complete his mission that created the biggest stir of the tournament.

Speaking with a slow, somber intonation in his voice, Federer informed the 17,000 onlookers at the O2 Arena that he couldn't give it a go against Novak Djokovic; that his back was ailing from the night before when he saved four match points against Stan Wawrinka in a Houdini-esque semifinal escape.

Federer looked bummed. Really bummed. After all, he's played 1,221 matches and has withdrawn from only three -- one of the great ironman feats in tennis. As Federer continued to address the crowd, we couldn't help but flash back to the more tenuous days of 2013, when he was busy falling in the second round of Wimbledon and laboring nearly as badly at the US Open. It was an astounding chain of events that quickly devolved into -- you guessed it -- a nauseating amount of retirement rhetoric.

Well, this is as good a time as any to point out Federer wasn't one of those defeatists. He didn't waste his efforts wallowing in his worst campaign in more than a decade, but rather put forth a blueprint for renovation.

After all, staggering toward the finish line is no way to go out, no matter how robust your credentials. Who wants to sit around and contemplate legacy anyway when you can still TKO guys like Andy Murray in under an hour and then pull off that magic act against Wawrinka at the ATP World Tour Finals?

What Federer really needed was a way to reconnect with the game. And that's literally what he did.

As 2013 wore on, Federer began experimenting with a blacked-out prototype racket, which was eye-opening considering the 17-time Grand Slam champion is famously fussy, if not fastidious, to a (double) fault. But even he knew that he had to make a change in hardware to keep pace with his contemporaries who were outhitting him on a weekly basis.

And the truth is, Federer's camp, along with pundits and a host of others in tennis circles, had been encouraging him to experiment with new equipment for quite some time. Federer had long been using the smallest head of anyone on tour, an old-school 90-square-inch Wilson Pro Staff, a worthy frame that had helped him build an empire of trophies and awards, but one with markedly less response than what the new normal had become.

He had always gravitated toward smaller-head rackets, even as teenager, in large part because one of his idols, Stefan Edberg, played with an 85-inch square version of the Pro Staff. And another of Federer's icons, Pete Sampras, was also using an 85. Federer himself played with an 85-inch-square head until he was a teenager.

Federer finally conceded, though. And last season, while in large part a bust, actually had an upside.

"It really started after the Australian Open in 2013," said John Lyons, global product director of Wilson Racquet Sports. "Federer said he was ready to try a new racket. It started with a couple of our guys going to meet with him in Switzerland. We brought a lot of different options in our line. At the time, we didn't have anything specific for him. He ended up liking one, and he played a couple of clay-court tournaments with a blacked-out racket that got people in the business buzzing about what it was."

The experiment moves on

As last year's Euro Slam season approached, Federer wasn't yet ready to make a permanent change and switched back to the comfort of his 90-inch Pro Staff. But mercifully, after his Wimbledon journey came to a halt about five rounds earlier than usual, Federer said he was ready to give something new a whirl -- and this time for good.

"That's when the real iteration of racket to racket to racket began," Lyons said. "We were making version after version, changing the head size, changing the stiffness, manipulating and the balance point and the construction of the racket.

"We went through 20-21 different rackets. Some he hit with for five minutes; some he used in competition. And when you think about it, with all the variables, we actually had somewhere in the neighborhood of 250 slightly modified versions."

It wasn't exactly a covert operation per se, but the folks charged with creating Federer's new frame were working far more earnestly than anyone realized.

Lyons said they manipulated the string pattern a few times as well. Federer experimented with an 18-main setup (for control), but he wasn't happy with the drop in power level. Wilson also changed the string spacing a couple of times, making some frames with a tighter pattern and others wider in the middle of the head. Though these subtle modifications might be imperceptible to the average player, Federer was able to detect the various adjustments.

It was a long, laborious process. Even as recently as Indian Wells this past March, Federer was still playing around with various versions of a new racket. As the summer moved into full swing, though, he began to get more and more comfortable with a particular racket. After months of trial and error, Federer had finally made a decision. We just didn't know it yet.

Before it was revealed to the public, Wilson, along with Federer, had to create a sparkling new aesthetic. "He's one of the only players involved in the cosmetic decision-making, and has absolute approval on how the racket looks," Lyons said.

Meet the Wilson Pro Staff RF97 Autograph

At the Rogers Cup in early August, Federer, at last, unveiled his new Wilson RF97 autograph racket -- a swanky frame with a black throat and red hoop, which, as Federer said, emitted a classic style but with a new, youthful look.

Other than the name, Federer's new racket is strikingly different than the others in the storied lineage of Pro Staff frames. It took a good deal of developmental time to find the optimal construction and appearance for the six-time year-end No. 1 player.

The head on the racket is 97 square inches, hence the name RF97, which gives him an eight percent increase in surface area to strike the ball. The larger size is very much on par with the rackets used by other players in the top 10. Both Djokovic and Rafael Nadal use 100-square-inch heads, while Murray wields a 98.

"We were working with Federer for well over a year," Lyons said. "He was using a prototype racket for quite a while, longer than we thought he would. We had actually been planning on creating a new Pro Staff before this whole [Federer] process started.

"We wanted something a little more modern, a little more like people play now. Traditional Pro Staff rackets have been very thin, very low-powered. But like anything else, the technology marches on -- and it has changed quite a bit, even from the time when Federer started his pro career."

What feeds the Federer racket?

The tennis-racket trend has changed in recent years. Although players enjoy the easy maneuverability of lightweight frames, in reality, they don't necessarily produce heightened ball speed. Think of the physics: If you have more mass, you're going to create more natural power.

And that's the idea behind the architecture of Federer's new frame. By using a combination of braided graphite and Kevlar, which has long been the makeup of the Pro Staff line, the strength, stability and power levels noticeably increase -- as does the static weight. In the Federer racket specifically, the contents aren't necessarily unique from previous Pro Staff models as is the distribution and overall volume of material used.

Federer, for what it's worth, is using a racket that weighs in north of 12.5 ounces -- far too heavy for the average club-level player or even high-level junior for that matter.

And though not many other brands use Kevlar in racket construction anymore, Lyons says it's not only an effective fiber but one that helps engender the unique Pro Staff response.

"A lot of people mistakenly hear 'Kevlar' and think body-proof vest and body armor because it's a really strong, stiff material," Lyons said. "And they incorrectly believe it works because the material is so strong that the bullet bounces off the vest. But that's not how it works at all. A bullet-proof vest protects you because it absorbs the energy. Kevlar is a very good energy-absorbing material.

"So what the Kevlar really does in a racket is it dampens the vibration and gives the racket a really solid feel. So when players hit the ball, it's a different kind of feel. Players who are used to that feel really like it."

String is the thing

It's all about the collision. Whatever racket you use, there's going to be serious impact. And it's how that ball reacts upon impact that can make or break results.

For Federer, he's historically used the same combination of string in his racket -- a natural gut in the mains and Alu Power Rough, which is a dented version of Luxilon Alu Power (a monofilament material or colloquially, a poly) in the crosses.

What does it mean? The gut in the mains gives him power, while the cross strings produce a spin-heavy, controlled response.

Said Lyons, Federer has tried other strings in the crosses, but hasn't deviated from gut in the mains in a quite some time.

Like most pro players, Federer doesn't string his rackets at a very high tension. When he used a 90-inch frame, he was stringing in the high 40s. With the larger head size and more powerful frame, Federer is stringing in the mid-50s.

Of course, as Lyons noted, that varies by surface and altitude and atmospheric conditions.

"If you're playing somewhere like Indian Wells with thin air, you'd string a little tighter as opposed to Miami, where conditions are more humid," Lyons said.

The result

Lyons would be the first to tell you Federer's turnaround this season isn't merely a manifestation of new technology.

"Look," said Lyons, "he had a bad back a year ago, which hindered his movement and flexibility -- this from a guy who has been nearly injury-free for most of his career. This is an increasingly fast sport, and if your back is hurting, that's a pretty big problem."

Look no further than Sunday's withdrawal from the World Tour Finals as proof.

Whatever the overarching reason, the racket has contributed to Federer's turnaround in 2014. He has approached the net with more aplomb, in large part because he can leverage his own power game. Federer leads all players with 72 match wins, 11 more than anyone else on tour, and has won more than 90 percent of his service games -- the most of any player in the top 10.

"Not to mention knocking on the door to Djokovic's world No. 1 ranking," Lyons added.

Life on the tennis court had been so unfailingly perfect for Federer throughout most of his career. But when things began to unravel a year ago, he was left searching for answers.

Federer found them, of course, but it took serious resolve and patience, not to mention some science and a fancy new new magic wand.