Roger Federer’s String Tension
What tension does Federer have his Wilson Pro Staff RF 97 Autograph Racket strung at?
In recent posts, I’ve looked at Roger Federer’s string saver pattern and the leather power pads he has installed in the throat of the frame. But what string tension does Federer use in his RF 97 Autograph racquet? Does it change dramatically throughout the year depending on surface and conditions? Let’s take a look.
Roger Federer’s String Tension Revealed
The image above is taken from the Laver Cup from 2018 in Chicago, and as you can see, Federer is stringing his mains at 27 kgs (59.5lbs) and his crosses at 25.5 kgs (56.2lbs).
The Laver Cup is an indoor event, so is he always using this tension across the year? The answer is no, but Federer doesn’t alter his tension that much throughout the season.
Of course, if Roger is playing somewhere like Indian Wells where the air is thinner, he will string a little tighter than when he travels over to Miami a week later, but the changes are only subtle.
His long term stringer, and friend, Ron Yu, of Priority 1 had the following to say:
Over the year Roger doesn’t change that much, his lowest tension will be around 26 kgs and his high will be around 27 kgs. Generally, he doesn’t vary much more than a kilogram throughout the season. He will, however, have racquets strung at different amounts for matches. For a three-set match we’ll string him eight racquets and he’s doing four at one tension, four at another. Typically four at 26.5 and four at 27. But he doesn’t vary too much at all from 26 to 27 all throughout the year. Ron Yu, Priority 1
Regardless of tensions, Federer’s racquets are always strung with 1.30mm Wilson (Babolat) Natural Gut in the mains and 1.25mm Luxilon ALU Rough in the cross strings.
Why Does Federer Use a Different Tension in the Mains Compared to the Crosses?
As you may have seen in the picture above, Federer always strings his cross strings one and a half kilograms less than his main strings.
The reason why different tensions are used is that when you have a softer string like a natural gut in a hybrid setup with a stiffer string, the softer string needs to be strung at a higher tension. This is to create a similar or equivalent stiffness level compared to the less elastic string in the crosses. This creates a more consistent feel across the string bed.
For example, if you have polyester strings in the mains, the softer string crosses are strung tighter to create a more even feeling stringbed. And for Federer it’s the reverse, the mains are strung tighter to create a more even feeling.
The other school of thought here is that stringing the crosses at a slightly lower tension increases the ‘sweet spot’ of the racquet. This results in more power due to ball pocketing as the main strings are allowed to move more freely.
Has Federer’s String Tension Changed Over the Years?
The change of racquet in 2014 had to bring about a tension change because of the head size increase. The Swiss switched from the long term 90 square inch racquet to a new 97 square inch model. With the 90 he was stringing at around 22-23 kilograms (~48lbs). However, the larger head size sees him string up at 26 and 27 kilograms.
The reason here is that the strings are slightly longer in the 97 square inch frame and the stiffness of a string when tensioned is directly proportional to its length. A larger head size racquet means that had he kept the same amount of pulled tension it would be distributed over a longer section of string which changes the feel and power. To offset this, you have to string at a higher tension on a bigger racquet.
Why Does Federer Use Priority 1?
The reason Federer uses Priority 1’s services is consistency across the year. While Federer isn’t one of the more meticulous players like Tim Henman, who was very sensitive around his equipment, he still wants that consistent feeling for the forty-odd weeks a year he spends on tour.
On-site stringers will always do a good job, but tournaments use different stringing machines, everyone has different techniques, and no two stringers will ever work in the same way.
By using Priority 1, Federer gets a guy in Ron Yu who travels with a stringing machine that is calibrated for accuracy at every tournament they attend. As a result, Federer gets the same feel, no matter where he is playing.
Yu even tries to keep the time between when the racquets come off the machine to when the player is scheduled to play consistently throughout the tournament.
That is because the tension of the stringbed will change depending on how long the racquet has been sitting around before play.
For example, if Federer’s first-round matches were done 8 hours before play, then Yu will maintain that for all future rounds. That means if the first match was a night match and the second round match starts at 1 pm, then the alarm is going off at 3 am to maintain that timing 😲 .
Meet the Man Who String’s Roger Federer’s Racquet
Do you have any questions about Federer’s string tension? Have you tried a similar string setup with different tension between the crosses and mains? Let me know in the comments.
Thanks so much for this extremely interesting post. I love to read about stuff like this, so it’s great to read while things are somewhat quiet.
Great article Jonathan, a pleasure to read it like always.
Out of context, ¿did Nadal ever used a smaller racket than he does now? I can’t imagine him playing with a 90′ headsize racket.
I don’t know a whole lot about Nadal’s gear tbh but he’s always used Babolat Aero Prodrive. 100sq”. From 2005 anyway.. L2 grip which is quite small, but dunno how many overgrips he uses.
I think he still uses that frame with a more modern paint job but not sure. He added some weight to the head a few years ago but that is the only change I have read about.
I use 58lbs (26.3kg) on the mains and crosses, never tried to lower any of them. I like the consistency on my shots with that tension (I use 100 head size).
I remember about Roger using a lower tension before, but as you explained, the bigger the head size needed to increase the tension to keep the same feel.
Great reading as always Jon!
What are you stringing with? If it’s a full bed of the same string, there’s not much benefit I don’t think.
The general rule is – higher tension = more control&accuracy, less power. With high tension the player must generate more power with his arms to hit hard. Or he prefers control over power. Is is not surprising, Fed needs rather control than power, given his perfect hand skills and playing rather to no-man’s land than very deep or extremely to the lines.
A great great post, Jonathan !
And a fascinating attention to details regarding the time lapses between matches.
“Yu even tries to keep the time between when the racquets come off the machine to when the player is scheduled to play consistently throughout the tournament.”
As Leonardo da Vinci said : “Les détails font la perfection et la perfection n’est pas un détail”.
Thanks. Yeah Ron Yu is hardcore, getting up at 4.30am to string a racquet 😀
I dunno what they are paid but it isn’t that well remunerated. Maybe there are bonuses for tournament wins though.
Fed has the gut for power. Has to string it fairly high otherwise he’d be spraying it around.
Most pros need a dead string given how they hit the ball.
You mean “power” of shotmaking or endurance of the whole bed? So the gut is not really “working string” but holding the bed in place?
Yeah, that is the compromise. Too elastic and and ball springs out like a jack-in-a-box, too stiff/tight, there is no feel and you get tired fast. And possibly injured.
This is why I’ve found that a basic large core nylon string (a.k.a. “synthetic gut”, blargh.) works just fine, especially when I’m not in the mood to get picky about strings.
You don’t get the best of both worlds, but you also avoid the worst: not too springy, not too stiff, slightly crisp, decent spin, forgiving. And cheap!
25 kgf for any 95-100 sq.in… sorry, ~610-645 cm2, and it’s ready to go.
@PRF The properties of natural gut mean it’s a power orientated string. If you string gut loose, you have tons of power.
Poly is a dead string, no power.
Fed will be using a Blue RF97 for the Laver Cup – https://www.perfect-tennis.com/laver-cup-2019-preview/
john elliot a pro stringer, recommends +2kg in the crosses to compensate for the loss of tension when passing the string crosses
I would say that doesn’t work in this setup here with natural gut. If you were doing a single string job with the same string in mains and crosses then you could pull the crosses tighter. I’m not sure about the tension loss argument, matter of choice tbh. The counter-argument is the strings are shorter in the crosses. Look at Yonex for example, they recommend you string the crosses looser in their racquets.
However, with poly, the tighter you string, the more you lose its elastic capabilities so not sure about ramping up the tension of it.
With gut mains, poly crosses hybrid setup you should always string the crosses looser.
I’ve a wise tension head and I find that if I strung my RF97As at the tensions that Roger has his racquets, they would be such a stiff string bed. I find that using lockout over CP offers a softer bed, but it would still be way too tight at the numbers above. The wise is calibrated correctly (I tested it). I’ve found that in my machine, anything over 46lbs is really stiff.
I’m trying to find the holy grail (so many are) of string, gauge, tension. I tend to like full beds of poly. I’ve experimented a lot, do you have any suggestions on the above?
With a full bed of poly, you will always have to string at a lower tension to get the benefits of the string.
Fed is using the softest string there is in his mains so that helps reduce the stiff feeling. And he is reducing the tension on the poly…
As for recommendations, it is hard to make suggestions off the cuff. What string setup have you been using most frequently in the RF97A and what do you like and not like about it?
Do you know how much tension Federer strung his racquet when he was using Pro Staff MID(85in.) ?
As far as I can remember, he wasn’t stringing hybrid before he moved to 90in. racquet if my memory is correct…..
I don’t unfortunately. I did once read he was stringing them at 55lbs with a full bed of Babolat Natural Gut, but I dunno how reliable that is.
The only way to find out for sure would be to get the info from him directly (assuming he even remembers) or from someone who used to string racquets for him pre 2000. Assuming they remember too!
But if I had to guess then the 55lbs / 24kgs mark doesn’t sound like it will be far off. Smaller frame but considering he was using full gut then, lower tensions would have been hard to control.
I have 2 questions:
1. There is 27 Kgs for Natural Gut (16 G/1,30) in main strings and 25,5 Kgs for LUX Alu Power Rough (17G/1,25 ) in Crosses on the picture to see! We see below ,,Pre Stretch- Yes! only for Natural Gut”. Strung at 9AM!
We see ,, Pre Stretch -Yes” for both , mains and crosses on second picture. Strung at 3PM!
Depending on Pre Stretch Level (10, 15, 20 or 25 %) It makes the difference how many of DT (Dynamic Tension) will be generated at the end!
So, which Level of Pre Stretch is used ?
2. Many players use Natural Gut for crosses and Luxilon Alu Power Rough for mains. So I heard it would enlarge the sweet spot in case of RF. on 97 Sq Inch Head.
How does it work? And in case of which frames does it would it also work?
I have talked about this here in more depth: https://www.perfect-tennis.com/pre-stretching-tennis-strings/
As for this specific example with Federer, Priority 1 tend to pre-stretch strings manually by using a door knob. So they are not using a machine to add X%,
I am not sure why he went from just mains to having both pre-stretched at the Laver Cup. I would think it is something to do with the duration between stringing and him playing. Or the conditions?
Lastly, making the sweet spot larger, where have you read this?
I would prefer using a door knob if I would string the natural gut strings. Would avoid breaking them. But I would not know how much of elasticity it has lost! So I could not compare stringing results from one to another racquet.
And I would use a machine to pre stretch the synthetic gut strings. There is less risk.
Sorry!I Can’t recall anymore. I couldn’t find who and where it was.
It was somewhere, someone of many of stringers /bloggers. Anyway
Federer used an orange, special addition racquet in every match at the Chicago Laver Cup. The black racquet pictured isn’t from that event. Just saying.
Not sure which picture you mean? Or where it was linked to the Laver Cup?