X-One Biphase is a multifilament string constructed using a new variation of the tried-and-true Tecnifibre process. According to Tecnifibre, X-One Biphase combines H2C (High Heat Capacity) microfilaments for power and feel, with NRG microfilaments for dynamic response. These microfilaments go through a chemical "trimerization" process to increase cohesion when dipped into polyurethane for bonding, and external protection against wear and notching. As with other Tecnifibre strings, the polyurethane also absorbs vibration and reduces shock. Tecnifibre tells us that its patented Biphase process extends string life by 20 percent and increases spin performance.
Extensive lab testing and playtesting by Tecnifibre have shown that X-One Biphase will reduce muscular fatigue, have dynamic properties similar to natural gut, and offer excellent durability.
X-One Biphase is available in 16 (1.30 mm) and 17 (1.24 mm) gauges in natural only.
IN THE LAB
We tested the 1.24 mm (17) gauge X-One Biphase. The coil measured 40 feet, 2 inches. The diameter measured 1.26 prior to stringing and 1.21 mm after stringing. We recorded a stringbed stiffness of 70 RDC units immediately after stringing at 60 pounds in a Wilson Pro Staff 6.1 95 (16 x 18 pattern) on a constant-pull machine.
After 24 hours (no playing), stringbed stiffness measured 64 RDC units, representing a 9 percent tension loss. Our control string, Prince Synthetic Gut Original Gold 16, measured 78 RDC units immediately after stringing and 71 RDC units after 24 hours, representing a 9 percent tension loss. X-One Biphase added 13 grams to the weight of our unstrung frame.
The string was tested for five weeks by 34 USRSA playtesters, with NTRP ratings from 3.5 to 6.0. These are blind tests, with playtesters receiving unmarked strings in unmarked packages. Average number of hours playtested was 25.7.
X-One Biphase is easy to install. The only problem we had was that the last inch or so of the already-flexible string would become a bit too flexible on blocked holes, necessitating a quick trim even though the point itself was still in good shape. For best performance, Tecnifibre recommends pre-stretching before installation, but it is not required. We pre-stretched our test sample, and advised our playtesters to do the same.
X-One Biphase also has a slight texture to it, but not enough to create a "sawing" of the crosses on the mains. Knots were easily tied, and there was no coil memory, no doubt due at least in part to pre-stretching. Best of all, straightening the strings after installation was a breeze, despite the polyurethane impregnation.
No playtester broke his sample during stringing, none reported problems with coil memory, none reported problems tying knots, and one reported friction burn.
ON THE COURT
Our playtester team loved this string, giving it the highest Power rating of any string we've playtested, dethroning Tecnifibre 515 16L (our previously highest rated string), and moving Tecnifibre NRG2 SPL 17 from second place to third highest of all time. They also loved the Comfort, awarding X-One Biphase our best-ever rating of all the strings we've tested.
In addition, our team rated X-One Biphase third place overall both in Playability and in Spin Potential (the Biphase process in action?), and fourth place overall in Touch/Feel. For good measure, they also rated it well above average in Control. The average score was good enough to vault X-One Biphase into fourth place of all the strings we've tested.
Six playtesters broke the test sample, one each at 5, 5.5, 7, 17, 26, and 55 hours.
X-One Biphase didn't just score first overall in the Comfort category, it far surpassed our previous first-place string. Even though competition among manufacturers has brought down the price of the traditional comfort string—natural gut—X-One Biphase's comfort-to-cost ratio could win it a lot of friends among those with arm problems, and that's not taking into consideration its many other fine qualities, or its ease of stringing compared to gut.
"Very good string. Gut-like playability. I love it." 5.0 male serve-and-volleyer using Wilson Surge strung at 65 pounds LO (Wilson Hyperlast 63)
"I am very impressed with this string. It is lively, produces a firm feel, gives me tremendous control, and holds tension well. This string has become my string of choice." 4.0 male all-court player using Pro Kennex Core 10 strung at 65 pounds LO (Tecnifibre X-One Biphase 17)
"This string reminds me of natural gut. After a couple of hours of play, it became very soft and comfortable. It holds tension well and shows very little string movement. I really love this string." 4.0 male baseliner with heavy spin using Dunlop 200G strung at 65 pounds CP (Prince Synthetic 16)
"This is great string. Very soft, yet powerful. I like it and would change to it." 5.0 male baseliner with moderate spin using Head i.x6 strung at 60 pounds LO (Wilson NXT 16)
"The string is soft and slippery, and the tip didn't fray during stringing. It has low coil memory and is very easy to work with. It has a soft feel during play, similar to my normal string, although with a little less control. I like this string and would recommend it to customers who want a softer feeling string. It is a good alternative to natural gut, and I would use it myself." 3.5 male all-court player using Völkl Tour 9 V-Engine strung at 54 pounds CP (Pacific TourGut 16)
"Very good string. Seemed to lose tension at about the same time that the fraying started (10 hours). Very easy on the arm with excellent spin potential and good control." 4.5 male all-court player using Yonex Ti 450 Long strung at 60 pounds CP (Prince Syn Gut w/Duraflex 16)
"This is a great string for overall playability, as good as anything else I've used. The comfort is superb. Excellent on the arm. I put string savers on after five hours of teaching and the stringbed really crisped up despite my low reference tension. The sound of the hit is terrific even without a dampener. For non-breakers this string has got to be a winner. It did fray immediately upon use. Not sure if this is a part of the design or not. Still, the overall feel was as gut-like as anything I've felt." 5.0 male serve-and-volleyer using Handler Arrow strung at 39 pounds LO (Gamma Zo Plus 16L)
"This is the best overall string that I have played with in the last two or three years. It has an outstanding combination of playability, control, touch/feel, comfort, and power. The degree of tension loss has been about average during the test period. This string was a definite pleasure to use and I will certainly include it in my inventory. Additionally, after stringing so many racquets with polyester lately, this string was a snap to install." 4.0 male baseliner with moderate spin using Wilson Triad 3 strung at 54 pounds LO (Prince Wrapsure 17)
"This is a great string to play with!" 4.0 male all-court player using Babolat Pure Drive strung at 53 pounds CP (Prince Syn Gut w/Duraflex 16)
"This string has a great feel to it." 5.0 male all-court player using Pro Kennex 7G strung at 59 pounds LO (Prince Polygut 17)
"I liked this string from the first hit. It has great feel, great ball grab, and offers very nice control. It reminds me of the qualities that natural gut offers. Having made that statement, I would guess that this string is made by Tecnifibre." 5.5 male serve-and-volleyer using Wilson Hyper Pro Staff 6.7 Extreme strung at 54 pounds CP (Natural gut 16/17)
"I really like this string. It is comfortable to play with, and had next to no movement. I felt as if I could hit out on my shots with control and confidence." 4.5 female all-court player using Prince Tour NXGraphite MP strung at 58 pounds CP (Tecnifibre NRG2 17)
"Good string for someone breaking standard synthetic strings on a regular basis." 5.5 male all-court player using Wilson Pro Staff 6.1 Classic strung at 62 pounds LO (Prince Syn Gut 16)
"No coil memory whatsoever. Very easy to string and weave. The playability is average, but the tension and resistance to movement are very good." 4.5 male all-court player using Prince More Control DB850 strung at 62 pounds LO (Prince Premier 16)
"I love this string. Because I string so tight, this type of string really suits me well. It did lose a bit of tension right before it broke, and the string that broke was a cross." 6.0 male all-court player using Prince More Precision strung at 70 pounds CP (Prince Sweet Perfection 16)
"This has a very nice feel to it for a 16-gauge string. It doesn't seem to drop much tension initially, but after 15 hours of play there is a noticeable decline in playability. The durability is surprisingly good. I would certainly recommend this string to players learning spin but looking to maintain feel in a more hardy string." 5.0 male all-court player using Head Liquidmetal Radical OS strung at 54 pounds LO (Prince Syn Gut Original 17)
"Overall, a pretty good string. I like it better than the string I normally use." 4.0 male serve-and-volleyer using Wilson Hyper Pro Staff 6.1 strung at 60 pounds CP (Wilson Synthetic Gut Extreme 16)
"An excellent overall string with outstanding playability, comfort, and power. It will rival current top-tier synthetics. My only wish—for this string and other top-of-the-line strings—is that there was better resistance to movement." 6.0 male baseliner with moderate spin using Völkl C10 Pro strung at 63 pounds CP (Gamma Live Wire XP 16/17)
"I really thought this string would lose more tension, but I was pleasantly surprised. Very nice tension maintenance for a soft string." 4.5 male all-court player using Wilson H Tour strung at 64 pounds CP (Bow Brand Champ 16)
"Very easy string to work with. Virtually no coil memory. Scored above average in most categories. I felt that I hit out with this string with no loss of control. Off-center hits were returned with adequate power and no harshness. While the strings move initially, they quickly locked into place, although that may have been due to notching. The string did fray on me near the end of its life, but this did not effect the playability." 4.5 male baseliner with heavy spin using Pro Kennex 7g strung at 68 pounds CP (Prince DNA Helix 16)
"I am pleased with this string, as it suits my game quite well. I am able to hit heavy topspin as well as underspin from the baseline, and have touch and control at the net. If the price is reasonable I would have no problem recommending this string." 4.0 male all-court player using Head i.x5 OS strung at 57 pounds LO (Wilson Sensation NXT 17)
"I just returned from a severe bout with tennis elbow, and I found this to be an excellent choice. I am pleased with the overall playability and comfort." 5.0 male all-court player using Wilson Hyper Pro Staff 6.1 strung at 50 pounds LO (Tecnifibre NRG2 17)
"This string is easy to install. The first couple of hours playing were nice. The string had a crisp, yet soft, feel. It began to feel a little dead after three hours of play." 5.5 male all-court player using Wilson Pro Staff Tour 90 strung at 61 pounds LO (Wilson NXT Tour 17)
"I didn't like having to pre-stretch the string. Otherwise, it was fine." 5.0 male serve-and-volleyer using Wilson Hyper Hammer 4.0 OS strung at 58 pounds LO (Wilson NXT 17)
"Very little give on pre-stretch, much like a poly. One of the quietest, most shock-absorbing strings I've hit. Dampening to the point of losing power. Would be excellent for over-powered frames. Very little movement with no signs of wear during test. Only moderate tension loss during four weeks of playtesting." 4.5 male all-court player using Völkl Tour 7 strung at 62 pounds CP (Tecnifibre NRG2 18)
"Aside from the pre-stretching part, handling the string was a breeze. The tie-offs were very easy and weaving it was a cinch, and there was no excessive coiling. The first two hours on court were great. It had good power, but not as much bite as some other strings. After that, it started to lose tension, and my shots started to fly. I had to hold back to keep the ball in play. This string has great power potential and is very easy on the arm." 4.5 male all-court player using Prince DB Control MP strung at 61 pounds LO (Prince Lightning XX 16)
"Pre-stretching helped make the string job easier. The string performed beautifully early on. Good gut-like comfort. After about nine hours of play, the they began moving more than the string I normally use." 5.0 male all-court player using Head Pro Tour 280 strung at 58 pounds LO (Prince Synthetic Gut 17)
"This string has a comfortable feel at this tension." 3.5 male touch player using Wilson strung at 56 pounds CP (Prince 17)
"I've never had to clamp a string harder to keep it from slipping out of the clamps. This happened three times and really wore the string. It was, however, easier to weave crosses and tie knots than any other string I've ever used. After the trouble I had stringing it, I didn't look forward to playing with it. However it totally redeemed itself. Power, touch, control, and comfort far exceeded expectations. I would look for this is the future for use in crosses. Tension retention isn't quiet as good as the rest of the string's performance." 3.5 male all-court player using Babolat Pure Drive Team + strung at 70 pounds CP (Gamma Poly / Pacific gut 18/17)
"I love the way the string plays when fresh, but after only 25 hours of play, it started to fray and the string lost its original feel and characteristics." 5.0 male serve-and-volleyer using Wilson H2 strung at 63 pounds LO (Wilson NXT Tour 16)
"This string is average in most areas. However, tension holding is below average. As a result of quick and excessive tension loss, control suffered after about a week of play." 4.0 male all-court player using Prince Tour NXGraphite OS strung at 58 pounds CP (Gamma TNT Pro Plus 17L)
"A good string offering power and control. Noticed tension dropped considerably after about nine hours of use." 5.0 male baseliner with heavy spin using Head Intelligence strung at 60 pounds CP (BDE Performance 16)
"This string felt loose from the beginning, even after pre-stretching." 5.0 male all-court player using Prince Attack 920 strung at 62/65 pounds LO (Prince Pro Blend 16)
"It thought this string would play better than it does, given its construction. It wasn't very forgiving on off-center shots. A bit tough on the arm, but good power on perfectly hit shots." 4.5 female all-court player using Wilson H Tour strung at 60 pounds LO (Gamma ESP 16)