Tecnifibre X-One Biphase String Review

Tecnifibre X-One Biphase 16 String

Video Review



Tecnifibre X-One Biphase String Scores
Power 90
Spin 66
Comfort 86
Control 72
Touch 80
String Movement 72
Playability Duration 78
Durability 73
Overall 82


  • Comfort
  • Power
  • Feel
  • Tension Maintenance


  • Too powerful for poly players
  • Not enough spin-potential for some heavy topspin players


Some tennis strings are very basic. Think traditional poly or synthetic gut. These strings consist of one or two parts and they tend not to specialize in the more expensive luxuries of comfort, feel and power. On the other end of the spectrum there is Tecnifibre X-One Biphase, a string with many carefully chosen and meticulously arranged parts. Like natural gut, X-One Biphase is a tad pricey, but that is to be expected given the considerable technology packed into this string. In the opinion of our playtest team, the price is worth it for the player who wants an incredibly arm-friendly string loaded with pop. While X-One Biphase is not natural gut, it did give our team the kind of comfort, feel, tension maintenance and power that very few comparable multis can offer. For our two big hitters, the downside of this string was in the form of less spin-potential and control, especially compared to their favorite polys. Ultimately, though, for the player who wants outstanding shock-absorption with a uniquely comfortable (yet wonderfully crisp) feel, X-One Biphase is simply one of the best options available.

Power - Score: 90

For our two playtesters, X-One Biphase delivered huge power. In fact, Brittany, with her nuclear powered backhand, required extra concentration to keep the ball in play. She said, "If I had to describe this string in one word it would be . . . Power! There was definitely a lot of power, which was especially noticeable on my groundstrokes. When I first started playtesting this string in my (also powerful) Yonex VCORE 100 S, there were definitely some balls that were launching well beyond the baseline. The stroke that took the most time to adapt to the string was my return of serve, as I had so much power that I had to dial back my normally aggressive return to keep the ball in the court."

"Power was there all right," said Karly, who got some serious pop even at higher tensions. She added, "I didn't have to try very hard to produce it with X-One Biphase. The sweetspot seemed to open up more and the ball really popped off the stringbed. No matter what shot I went for it was easy to put some pace behind my shots. At times the power was almost too much for me, so I strung it at a higher tension to get more control. Even then the strings felt really powerful. X-One Biphase is easily one of the more powerful multifilaments I've hit with."

Spin - Score: 66

X-One Biphase, with its sticky coating, does not snap back like a slick poly. Nor does it have the low powered response that many big hitters prefer for creating spin-friendly head speed. For these reasons, it is not surprising that Karly couldn't get enough grip on the ball. She said, "Spin was not something that came easily, if at all. The strings didn't offer much grip or bite, so it was tough putting any type of spin on the ball. Most of my shots were noticeably flatter than usual. It was somewhat frustrating because of how powerful the string was -- I couldn't rely on spin to help the ball land in and I wasn't playing as consistently."

Agreeing with Karly, Brittany also could have used a little more bite. She said, "While I did find a little bit of success with spin, I was aching for more. Since this is such a powerful string I needed every ounce of spin to keep the ball in the court. I noticed this slight lack of spin when I was reaching for a ball and would have to throw the ball up defensively. My defensive shots did not have the extra spin needed to keep the point going. The spin made a small difference in my pick up/reflex volleys as well, as I noticed they were launching slightly off of my racquet."

Comfort - Score: 86

Boasting an army of cushiony filaments that are infused and bonded with stretchy polyurethane, X-One Biphase gave our team absolutely outstanding comfort and shock absorption. Brittany was clearly impressed, saying, "I found this to be a very, very comfortable string to hit with. It was strung at 56 lbs in my racquet and I had absolutely zero problems. I did not experience any pain or discomfort. In fact, I sometimes didn't even notice when I would mishit or hit outside the sweetspot because I couldn't feel the difference. I thought this string did a great job absorbing any shock. I also enjoyed the feel of this string, as it was very easy to use and adjust to."

Karly appreciated the expanded sweetspot. She said, "It's easy to say comfort was one of the string's standout features. I loved how soft X-One Biphase was on the arm. It was anything but stiff. I never had to worry about my arm feeling sore, even when I strung it tighter. And the string didn't feel mushy. The response was very crisp and slightly firm, but never harsh on the arm. I also thought the sweetspot increased slightly with this string, and was more responsive. The change in feel when hitting outside of the sweetspot wasn't as drastic as it is with a stiffer string. Overall, X-One Biphase was a very comfortable, lively and responsive string."

Control - Score: 72

Powerful strings like X-One Biphase usually return too much energy to the ball for the biggest hitters, especially those who need the stiff response of polyester to bring the ball down. This helps explain why Brittany struggled a little with control. She said, "With the power, there came a noticeable lack of control for me with this string. I think this is mainly due to the fact I have a very fast swing speed. I was having a hard time controlling my shots and keeping them in play. I found myself trying to swing slower to keep the ball in play when going for winners. That being said, I think pairing this with a poly to create a hybrid would give me the control that I was looking for."

Sharing Brittany's sentiments, Karly also could have used more control. She said, "Given that X-One Biphase is one of the most powerful strings I've hit, control was not one of the string's strong suits. I really had to concentrate on my shot placement because the strings were so lively. It was tough when trying to hit precise shots. I even strung it at a higher tension to get more control, but I still had a hard time with all the power. Hitting with control did not come naturally with X-One Biphase."

Playability Duration - Score: 78

For our team, X-One Biphase settled in nicely and offered long lasting playability. It even held up under the brutal pressure of Brittany's big strokes. She said, "I thought the playability duration was longer than expected. Compared to some other multifilaments I have playtested, I would say this string lasted a couple hitting sessions (3-5 hours) longer. I did notice a slight drop in playability after 6 or so hours of play. After that drop it held up remarkably well for the next week. The main thing I noticed was there wasn't that much change, aside from maybe a little more power."

Though she had some issues with the power, Karly found the playability to remain quite consistent after settling in. She said, "The ball seemed to really fly off the racquet, but after the first couple of hits the strings seemed to settle down a little bit. Though it still was a very powerful string even after settling in. Once it settled in the racquet, I thought it kept its tension extremely well. I also noticed that it hardly frayed at all, unlike some similar strings. I found the string to have exceptional playability."

Overall - Score: 82

What type or player would you recommend this to?

Brittany - "I would recommend this to two different types of players. The first would be a player who likes to hit a flat ball but has a slow to medium speed stroke, and is looking for power and comfort. The second would be a player who has faster strokes and is using a poly, but is looking to add a little more pop and comfort. For this person, X-One Biphase would be perfect in a hybrid set-up."

Karly - "A player with flatter strokes who doesn't break strings easily and wants a soft, powerful string."


Brittany - "I liked that there was easy access to power (a little too much at times), the comfort and the feel of the string."

Karly - "One of the top multifilaments in power, comfort and playability."


Brittany - "Due to my faster swing speed, I need a string with more control and spin."

Karly - "It was a hard string to produce spin and control my shots with."

Comparing the string to others they've tried, our testers said:

Brittany - "This string is very similar to Wilson NXT. There was similar power and comfort characteristics between the two strings. I would say that X-One Biphase is slightly more durable and that it has a slightly different feel than NXT (not better or worse, just different)."

Karly - "The characteristics were so similar to NRG2. Both were extremely comfortable on the arm, generated a ton of power and could've improved in the spin and control departments. I say the main differences between the two were the feel and playability. X-One Biphase had a crisper response, whereas NRG2 felt almost mushy, and X-One Biphase didn't fray as easily as NRG2. Other than those two characteristics, the strings played virtually the same."


(Scores are determined by averaging individual play test scores)

Brittany's Scores
Power 8.8 Playability Duration 7.2
Spin 7 Durability 7.2
Comfort 8.5
Control 7.2
Touch 8.5
String Movement 7.1
Overall 7.8
Karly's Scores
Power 9.1 Playability Duration 8.3
Spin 6.1 Durability 7.3
Comfort 8.7
Control 7.1
Touch 7.5
String Movement 7.2
Overall 8.6

Playtester String Setups

Racquet: Dunlop Biomimetic M2.0
Playtest Tension: 57 lbs
Usual String: Wilson NXT 16g

Racquet: Yonex V-Core 100 S
Playtest Tension: 57 lbs
Usual String: Polyester 16g

Review date: June 2013. If you found this review interesting or have further questions or comments please contact us.

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