Playtest: Isospeed Professional 17
By Greg Raven
Isospeed Professional is a multifilament string composed of Power Ribbons and polyamid filaments. According to Isospeed, the polyamid filaments are pre-stretched during manufacturing, which helps with tension maintenance.
The Power Ribbons are made of a unique polyolefin, which Isospeed says provides gut-like properties. The surface of the string is welded under heat, which allows the inner filaments and ribbons to operate independently.
Isospeed tells us that Professional is designed for players who seek gut-like performance, yet want to have more durability in a weather-resistant string. Isospeed markets Professional as offering speed and arm protection.
Professional is available in 17 gauge in natural only. It is priced from $12 per set. For more information or to order, contact Isospeed at 866-554-7872, or visit isospeed.com/en/.
In the lab
We tested the 17-gauge Professional. The coil measured 41 feet. The diameter measured 1.19-1.23 mm prior to stringing, and 1.16-1.19 mm after stringing. We recorded a stringbed stiffness of 73 RDC units immediately after stringing at 60 pounds in a Wilson Pro Staff 6.1 95 (16×18 pattern) on a constant-pull machine.
After 24 hours (no playing), stringbed stiffness measured 63 RDC units, representing a 14 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. Professional added 12 grams to the weight of our unstrung frame.
The string was tested for five weeks by 37 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 30.3.
Out of the package, Professional feels thick and substantial, despite its thin gauge and light weight. It marks a bit at clamping points, and if you hurry when installing the crosses it looks a little beat up when you’re done. Some stringers recommend waxing the mains before installing the crosses to mitigate this.
No playtester broke his sample during stringing, 14 reported problems with coil memory, one reported problems tying knots, and five reported friction burn.
On the court
Just about all of our playtesters found Professional to be a great string, scoring it well above average in every one of our nine categories. Of the 111 published playtests we’ve performed, Professional’s ratings were in the top 20 in the Playability, Power, Control, Comfort, and Spin Potential categories. As a result, Professional garnered a top-20 overall average score of all published string playtests to date.
Three of the playtesters broke his sample during play, one at one hour, one at 15 hours, and one at 18 hours.
According to our playtest team, Professional is a balanced string that will benefit just about any kind of player. This is clear from the ratings, but it can easily be seen in the comments, too.
One aspect of our playtest results that jumps out at you is that Professional received high marks for Durability, even though it’s a 17-gauge string.
Interestingly, even though Professional lost more tension than some other strings we’ve tested, three playtesters specifically told us that it holds tension well. Most of our playtesters either didn’t notice or didn’t care, and only one playtester complained of tension loss.
“This is the most comfortable string I’ve ever used. Though impact feels very soft, the response is crisp and precise.” 4.0 male all-court player using Wilson nTour strung at 65 pounds LO (nylon multifilament 16)
“This string has superior comfort, control, and feel. No dampener needed. The low power makes it perfect for big hitters, and the low trampoline affect makes it great for those who prefer low tensions. The combination of comfort and control are truly impressive.” 4.5 male serve-and-volleyer using Handler Arrow strung at 58 pounds LO (Gamma Dura Blast 16)
“This string is very comfortable. It has a crisp liveliness and simply great control. After 15 hours, there is no sign of fraying.” 4.5 male all-court player using Völkl DNX 9 strung at 58 pounds LO (nylon 17)
“This string has a nice, quiet, muted response. Control is excellent and the comfort level is high.” 5.0 male all-court player using Pro Kennex Kinetic Pro 7g strung at 63 pounds LO (Tecnifibre Promix 16L)
“This string does not install nearly as well as it plays. It has excellent control, power, and comfort. I prefer playable multifilaments with excellent control and this string is one of the best I’ve tried.” 5.0 male all-court player using Head i.prestige Mid strung at 55 pounds CP (Gamma Live Wire Professional 16)
“Initially, this string has excessive power, but eventually the string settles and has superior touch, comfort, and spin. It surpasses my typical set-up, which I’ve been using for two years. I would definitely try it in the crosses, if not the whole string bed.” 4.0 male all-court player using Prince O3 Tour MS strung at 62 pounds LO (polyester/nylon 16/17)
“This string starts a bit stiff, but the spin is out of this world. It softens quickly and becomes very easy on the arm. Overall, I’m amazed by the spin and comfort.” 4.0 male baseliner with heavy spin using Dunlop 200G (Muscle Weave) strung at 65 pounds CP (Prince Synthetic Gut w/Duraflex 17)
“This string has a soft feel. The comfort and playability definitely make this a high-end string.” 3.5 male all-court player using Völkl Tour 9 V Engine (70 Holes) strung at 55 pounds CP (Babolat VS Team 17)
“This is definitely the best string I’ve ever used. It has a gut-like crispness with amazing comfort and control.” 4.5 male all-court player using Gamma Diamond Fiber M-6.5 MP strung at 53 pounds LO (nylon 17)
“Comfort, comfort, comfort. Plays very well at low tensions. For a durability string, this has great touch. This string can handle a wide range of shots and swing speeds. My arm thanks you.” 5.0 male all-court player using Prince Triple Threat Warrior MP strung at 48 pounds LO (Wilson NXT Tour 17)
“Stringers take note: the crosses do not pull easily. Perhaps try some wax. Secondly, don’t be fooled by the way this string handles, it is NOT a polyester; it is quite soft. Unfortunately, soft strings usually have too much rebound energy, making them hard to control. This string, however, provides refreshingly soft comfort without excessive power. This is not a ‘dead’ string by any means; if your mechanics are in order, the juice is there. It plays with more predictability and control than any ‘comfort’ string I’ve ever used. It defies categorization and will probably prompt a lot of misreadings. This is not a pedestrian monofilament, it has more nuance than a 1982 Bordeaux. If you like a comfortable, muted response with tons of control, try this string.” 4.5 male all-court player using Head FXP Prestige Team strung at 56 pounds LO (Babolat Xcel Premium 17)
“The playability is above average and the durability is truly impressive for a soft string. Not only is spin production is easy, but the strings don’t move. Tension maintenance is excellent; the strings feel fresh after 16 hours.” 4.5 male all-court player using Völkl DNX 8 strung at 53 pounds CP (Gamma Live Wire XP 17)
“This string looks and feels like polyester, but turns out to be fairly soft. The control is excellent and volleys are crisp, but it lacks pop on serves and has merely average spin. This would be great for nylon users who are looking for more control and durability.” 4.0 male touch player using Prince O3 Red MP strung at 56 pounds LO (Gamma TNT2 Pro Plus 17L)
“This string has a solid feeling. The power and control are apparent from the very first hit. It is not quite as playable as the softest multifilaments, but it does offer increased durability.” 5.5 male all-court player using Head Liquidmetal Instinct Tour XL strung at 56 pounds CP (Tecnifibre NRG2 17)
“This string plays on the stiff side. General performance, however, is good. It would work great as a main with a soft cross.” 3.5 male touch player using Wilson Hyper Hammer 2.7 strung at 58 pounds CP (Prince Premier w/Softflex 16)
“This string has just the right amount of pop. It also has exceptional control. It is recommended to those looking for a ton of spin with a crisp response.” 5.0 male all-court player using Head Liquidmetal Radical MP strung at 57 pounds LO (Prince Synthetic Gut w/Duraflex 17)
“Great control on serves and nice touch on volleys, but definitely lacking some zip from the baseline. Those looking for depth and power should eat their Wheaties prior to playing.” 6.0 male serve-and-volleyer using Wilson KSix One 95 (16x18) strung at 60 pounds LO (Wilson NXT 16)
“This string is very crisp, with good control and spin. In order to get some much needed playability, though, I would use it in the mains with natural gut crosses.” 5.0 male all-court player using Völkl DNX 10 MP strung at 59 pounds CP (Völkl Power-Fiber 17)
“This is one comfortable string. The impact feels very soft. The control is evident from the first hit. Durability and power are not strong suits, but the overall playability is quite high.” 4.0 male all-court player using Wilson Hyper Pro Staff 5.0 MP strung at 58 pounds LO (Prince Synthetic Gut w/Duraflex 17)
“This is definitely a control string; it is not recommended to those in search of power. It has great touch and feel, with a very stable response. String movement is minimal and durability excellent.” 4.0 male baseliner with moderate spin using Prince O3 Speedport Red strung at 54 pounds CP (Prince Lightning XX 17)
“While it has great control, bite, and durability, it lacks the ‘wow’ factor.” 5.0 male all-court player using K Six.One Tour strung at 57/56 pounds LO (Wilson NXT Tour 18)
“This string stays resilient for a long time! The string bed delivers a very crisp and comfortable response.” 5.5 male all-court player using Wilson nTour Two strung at 55 pounds LO (Wilson NXT 16)
“Initially, this string was a tad stiff and unplayable. After a short duration, however, the dwell time, touch, and comfort turned out to be very impressive.” 5.0 male serve-and-volleyer using Dunlop 200G (Muscle Weave) strung at 60 pounds CP (natural gut 16/17)
“This string has nice pop and great control. The increased dwell time helped with ball rotation. I’ve never hit a better kick serve. While it doesn’t have great feel, it produces heavy and very precise shots from the baseline.” 5.0 male all-court player using Prince Graphite Classic MP strung at 62 pounds CP (Prince Premier w/Softflex 17)
“Stencil ink does not adhere to the surface very well. It is very comfortable and has good control. There is definitely some string movement. It could use a little more power, but it has truly great touch at net. The ball comes off the string bed with a slow predictability. This is the opposite of a string that sprays the ball. I never felt like I had to check my swing speed or modify my swing path to keep the ball in play.” male all-court player using Wilson Hyper Pro Staff Surge X MP strung at pounds LO (Gamma TNT Fat Core 16)
“This string is very durable with great spin. It breaks in very quickly and holds tension well.” 5.0 male baseliner with heavy spin using Babolat Aeropro Drive strung at 56 pounds CP (Prince Synthetic Gut w/Duraflex 24)
“Keeps tension really well, but doesn’t have much touch and feels tighter than most nylon based strings.” 5.0 male all-court player using Wilson n1 strung at 65 pounds LO (Wilson NXT 16)
“While the power and comfort are high, it simply does not last long enough for my heavy topspin game.” 5.0 male baseliner with heavy spin using Wilson nPro Surge strung at 58 pounds CP (polyester/nylon 16)
“This string is not as playable as my typical multifilament. Full swings from the baseline have good power and control, but touch and spin shots are harder to execute.” 5.5 male all-court player using Head Flexpoint Instinct strung at 61 pounds CP (Gamma Live Wire Professional 16)
“Good control. No major flaws, no major adjustments required. Average playability. There is nothing about it that grabs my attention.” 5.5 male all-court player using Dunlop Aerogel 200 strung at 64 pounds LO (Prince Synthetic Gut w/Duraflex 16)
“Heavy kinking made this tough to string. It plays pretty good for a durability string, but it would need more comfort and touch to reach a wider audience.” 5.0 male all-court player using Prince O3 Spectrum Hybrid Oversize strung at 62 pounds CP (Prince Premier w/Softflex 16)
“String handles like a cross between a polyester and a kevlar. Control, durability, and resistance to movement are above average, but touch is lacking.” 4.5 male baseliner with heavy spin using Pro Kennex Kinetic Pro 7g strung at 60 pounds CP (Prince Pro Blend 16)
“This is recommended to string breakers. The power is surprisingly high. Comfort and touch leave something to be desired.” 5.5 male all-court player using Wilson nTour strung at 55 pounds CP (Wilson Extreme Synthetic Gut 16)
“This is a comfortable string with good touch, but the durability is lacking.” 5.0 male all-court player using Babolat Pure Drive (with Cortex) strung at 58 pounds LO (Wilson NXT 16)
“Plays like a forgiving polyester — crisp, but easy on the tendons. It has the playing characteristics of a durability string. This could be a new niche string for string breakers with arm problems. I prefer more playability and touch.” 5.0 male all-court player using Wilson Hyper Pro Staff ROK MP strung at 63 pounds LO (Wilson Sensation 16)
“This string has excessive coil memory and poor tension maintenance. The lack of feel and touch make it very hard to control the depth.” 5.0 male all-court player using Pro Kennex Core 1 #10 strung at 65 pounds LO (polyester/nylon 18/17)
(Strings normally used by testers are indicated in parentheses.)
|EASE OF STRINGING
(compared to other strings)
|Number of testers who said it was:|
|about as easy||16|
|not quite as easy||13|
|not nearly as easy||2|
(compared to string played most often)
|Number of testers who said it was:|
|about as playable||11|
|not quite as playable||11|
|not nearly as playable||3|
(compared to other strings of similar gauge)
|Number of testers who said it was:|
|about as durable||12|
|not quite as durable||1|
|not nearly as durable||2|
|From 1 to 5 (best)|
|Resistance to Movement||3.6|
See all articles by Greg Raven
About the Author
Greg Raven is an associate editor for RSI magazine and technical writer. He is certified as a Master Racquet Technician by the U.S. Racquet Stringers Association. He can be reached via e-mail at firstname.lastname@example.org, or through Facebook, LinkedIn, and Twitter. He plays tennis five days a week, and is turning into an avid cyclist.
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