Tennis Industry magazine


Playtest: Gosen Polylon SP

By Greg Raven

Polylon SP (the SP stands for “supreme playability”) builds on the successes of Gosen’s Polylon and Polylon Comfort strings. (See our playtest report of Polylon Comfort in the June 2003 issue of Racquet Tech magazine.) Unlike the other two Polylon strings, however, Polylon SP is a monofilament of specially blended polyester.

Gosen Polylon SP

According to Gosen, Polylon SP is for advanced players looking for more softness and resilience in a polyester string, who don’t want to give up power or durability.

Polylon SP is available in 16 and 17 gauge (1.30 mm and 1.24 mm) in pearl white. It is priced from $4.50. For more information or to order, contact Gosen at 800-538-0026, or visit Gosen on the web.

In the lab

We tested both the 16- and 17-gauge Polylon SP. We recorded (see results below) stringbed stiffness immediately after stringing at 60 pounds in a Wilson Pro Staff 6.1 95 (16×18 pattern) on a constant-pull machine, and then retested after 24 hours (no playing). 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.

The string was tested for five weeks by USRSA playtesters, with NTRP ratings from 3.5 to 6.0. These are blind tests, with playtesters receiving unmarked strings in unmarked packages.

Playtesters were advised to increase tension by 5 percent compared to normal for a nylon string. Despite the seemingly minor difference in thickness between the two, the 17-gauge Polylon SP was much easier to work with than the 16-gauge, especially when weaving the crosses. Polylon SP does not elongate much during tensioning, and crosses are easy to pull, due to the smooth string surface.

Gosen Polylon SP 16 gauge 17 gauge
Coil measurements 42’ 5” 41’ 9”
Diameter unstrung (mm) 1.25 1.24
Diameter strung (mm) 1.22 1.21
RDC stringbed stiffness new 73 71
RDC stringbed stiffness after 24 hrs. 68 66
Tension loss (lbs) 5 5
Tension loss % 6.85 7.04
String Weight (grams) 14.8 13.95
Number of playtesters 30 35
Broke during stringing 0 0
Excess coil memory 14 9
Difficulty tying knots 4 1
Friction burn 3 1
Average playtest duration (hrs) 21.6 28.81
Broke during play 6 4
Break hours 2, 8.5, 12, 12, 18, 37 2, 9, 12, 28

On the court

Although our playtesters gave higher ratings to 17-gauge Polylon SP than to the 16-gauge, each scored very well, especially in Durability, Tension Holding, and Resistance to Movement. Compared to other strings of similar gauge, Polylon SP’s durability placed very highly with our playtesters, and when compared to all strings, each gauge scored well above average of the 95 strings we’ve playtested to date in Durability. In addition, 16-gauge Polylon SP gathered first place in Tension Holding of all the strings we’ve tested thus far and second place in Resistance to Movement. The 17-gauge Polylon SP’s scores show this was no fluke, rating a second place overall for Tension Holding, and sixth place for Resistance to Movement. The difference between the two gauges is that Polylon SP 17 also scored well above average for Playability, Power, Control, and Spin Potential. As a result, each gauge’s overall score is well above average.


Gosen’s Polylon SP is more proof — as if any is needed — that string manufacturers are making ever-better polyester strings. The thing to keep in mind is that multifilament nylon strings are getting better, too, and yet here again we see average players appreciating what a well-designed poly can do. Polylon SP also follows the trend toward better and better playing polys at more and more affordable prices. This combination should make it easier for stringers to keep the parents of hard-hitting juniors happy.

Comments for Polylon SP 17

“I used to play with poly strings, but switched to a multi for more feel on my strokes. This string really surprised me. It was easy to nstall, and although it did feel harsh to begin with, after the first hour of play it settled in for me and now plays as well as any string I’ve used. I have excellent control and the feel is there, durability is outstanding and the feel is above average. Get this string on the market soon: I need to buy some.” 4.0 male all-court player using Yonex RDX-500 MP strung at 66 pounds CP (Wilson Sensation 16)

“Great string. I would recommend this to players needing durability without sacrificing feel. I was able to hit a harder ball with less effort, due to the tightened rebound. I had great response to spin, too.” 5.0 female baseliner with heavy spin using Head Liquidmetal 4 strung at 58 pounds LO (Wilson Stamina 17)

“I think this poly plays very well. I feel it outperforms most of the hybrids I have tried recently. I would recommend this string highly to better players.” 5.5 male all-court player using Wilson nSix-One strung at 63 pounds CP (Wilson Sensation 16)

“This is a stiff string with very little stretch, which is great for the control/touch player. It maintains tension with very little string movement. Durable, with reliable and consistent stroke production.” 4.5 male all-court player using Fischer Twin Tech 950 FT strung at 62 pounds CP (Gamma Synthetic 17)

“This seems like a great overall string. Very easy to work with while stringing. Allows a nice “cinch” when tying knots. I was surprised by the fact that there was very little movement in the string during play.” 3.5 female all-court player using Prince Air Launch B925 strung at 64 pounds CP (Wilson NXT 17)

“This is one of my favorite test strings. I am impressed by its overall versatility. While the string does not stand out as being excellent in any given category, the product is clearly above average in every category. As a result, I feel that this is an overall great string. I am most impressed by the power, comfort, and control. This string also offers a nice, solid, crisp feel.” 3.5 male all-court player using Wilson Hyper Pro Staff 6.1 strung at 60 pounds LO (Wilson Sensation 16)

“This is one great string. Almost no tension loss or movement in close to 60 hours of playing and teaching. I will take 10 reels!” 4.0 male all-court player using Head Liquidmetal 1 OS strung at 63 pounds LO (Head Ultratour 17)

“Strong coil memory during unwinding, strong snap-back energy during stringing, but there was no kinking. Crosses were easy to feed throughout except for the very last crosses on an ATW pattern. The tips held up during stringing and the knots were easy to cinch up. According to my StringMeter, there was little tension loss after 24 hours, and amazingly for such a soft-playing string, there was only about five percent tension loss after 17 hours of play and 15 hours of teaching. This sample showed no notching, and I experienced no movement during play.” 4.5 male baseliner with heavy spin using Head Flexpoint Radical MP strung at 63 pounds CP (Unique Tourna Poly Big Hitter 17)

“Pretty nice string. Good, balanced performance. Better spin and touch than I thought I was going to get. Seemed to play better toward the end of its life. Playability was quite impressive throughout the trial period as it held its power and control for both groundstrokes and my serve. Volleys were powerful but not crisp. Topspin was easy to generate during groundstrokes. I would definitely recommend this string not only to string breakers but anyone looking for a soft-feeling string that holds up like a tough polyester with more power on groundstrokes, volleys, and serves. A responsive string from the baseline with great control and spin potential.” 5.0 male all-court player using Prince DB 850 strung at 63 pounds LO (Prince Premier/Babolat VS Touch 16/15)

“This is a good string. Not too stiff for a poly, with a lot of control.” 5.0 male serve-and-volleyer using Wilson nPro Surge strung at 52 pounds CP (Wilson)

“Initially I expected this string to be really stiff with no feel. However, I was pleasantly surprised, as it has good feel and touch for a durable string. The tension loss is greater than expected, but otherwise a very nice combination.” 5.0 male all-court player using Wilson nSix-One strung at 62 pounds LO (Wilson NXT Tour 17)

“I found the string to my liking even though it’s a poly. I normally wouldn’t use a poly, but this one played great.” 3.5 male serve-and-volleyer using Wilson nPro Surge strung at 53 pounds CP (Babolat VS gut 16)

“Decent feel for a poly. Easy to install. Holds tension well, also.” 5.5 male all-court player using Head Ti.Fire strung at 65 pounds LO (Gamma Live Wire 16)

“This string felt good from the first hit.” 4.0 male all-court player using Wilson Sledgehammer 3.8 strung at 67 pounds CP (Gamma Live Wire 17)

“I love this string, but I’d like to try it in a thinner gauge.” 4.5 male all-court player using Babolat Aeropro Drive strung at 62 pounds LO (Babolat Xcel Premium 17)

“Normally, I don’t like polyester string. However, this string was easy to work with. It plays very well. I was able to get great spin, and control was very good. As a college coach, the durability interests me.” 5.0 male all-court player using Babolat Zylon 360 MP strung at 58/56 pounds CP (Various 16/17)

“Very solid string.” 6.0 male serve-and-volleyer using Prince Turbo Shark MP strung at 65 pounds CP (Prince Sweet Perfection 16)

“Very interesting string to work with. Even though it was more difficult to install, I found that I played quite well. Certainly it is more durable than my normal string, but I don’t think I will switch.” 4.5 male all-court player using Wilson n5 strung at 63 pounds LO (Wilson Reaction 16)

“This string surprised me with its firmness and ability to create spin. Although it has a firm feel it creates adequate power and good control. A good string if the player can generate power.” 4.0 male all-court player using Babolat Pure Drive + strung at 58 pounds CP (Babolat VS Team 16)

“This string seems to play very well.” 4.0 male all-court player using Prince Turbo Shark MP strung at 62 pounds CP (Gamma Advantage 16)

“A wonderful string to work with. I look forward to installing it for my clients. It loses tension at about the same rate as other strings. It broke early, but not as early as my usual string. It has a good pop to it.” 5.0 male all-court player using Head Liquidmetal 1 strung at 62 pounds CP (Wilson Sensation Supreme 16)

“During the first few days of playing, this was like most other polyesters: Lively and responsive. After that I think the tension dropped, and control became an issue. As with most strings it settled in, I adjusted to it, and enjoyed it. I’m still using these strings daily!” 5.0 male baseliner with heavy spin using Head Liquidmetal 2 strung at 65 pounds LO (Wilson Sensation 16)

“The more I played with this string the better I liked the feel.” 4.0 female all-court player using Head strung at 60 pounds LO (Wilson Synthetic Gut 17)

“I basically like the feel, considering it’s a monofilament, but I would have preferred a thinner gauge.” 4.0 male all-court player using Head Protector MP strung at 55 pounds CP (Gamma ESP 17)

“Good string. Initially very good, but after ten hours it felt just normal.” 5.0 male baseliner with moderate spin using Babolat Pure Control Zylon + strung at 62 pounds LO (Babolat Super Fine Play 17)

“Feels like a polyester. No feel for the ball. I don’t like the sound it makes on impact. It feels solid, but there is no “spring.” It slices okay, though.” 4.5 female all-court player using Dunlop strung at 63/60 pounds LO (Any 17)

“I liked the way the string bites into the ball, helping me produce spin but wish the string had a little more elasticity and was easier on my arm.” 4.5 male all-court player using Wilson H-Tour strung at 58 pounds LO (Wilson NXT 15L)

“This string appears to have good tension maintenance. Touch and power are compromised slightly. Does not have much movement on the stringbed after ten hours of play time. Was a little harder on the arm compared to softer multifilament strings.” 5.0 female all-court player using Dunlop 300G strung at 59 pounds CP (Dunlop Max Comfort 16)

“This playtest sample played well during the first five hours of use. After that, it seemed to deaden a little. Decent, but not top of my list.” 3.5 male baseliner with heavy spin using Head Flexpoint Radical OS strung at 62 pounds LO (Forten Aramid Gear/Tecnifibre 515 15/17)

“Fairly good-playing polyester. Resiliency decreased about eight hours into play. Strings never moved and hardly notched. Good for string breakers, bad for finesse players. Doesn’t seem to move the ball much, even when spin strokes are exaggerated.” 4.0 male all-court player using Zebest Fine 90 strung at 63 pounds LO (Cyberfire 17)

“This string installs relatively easily. There wasn’t any excess coil memory at all. The playability leaves a lot to be desired. I feel like I am hitting with a piece of lumber.” 5.0 male all-court player using Head Flexpoint Radical MP strung at 69 pounds LO (Bow Brand Championship gut 17)

“For my style of play, this string requires a great deal more effort to get the bal deep. In all other aspects, it was at best an average string.” 4.0 male baseliner with moderate spin using Fischer Twin Tec 950 strung at 63 pounds LO (Klip X-Plosive 16)

“I did not like the way my racquet played at the higher tension recommended for this string.” 4.5 male baseliner with moderate spin using Prince TT Attitude strung at 59 pounds LO (Prince Synthetic Gut w/Duraflex 16)

“I am not enjoying this string. It may last a long time, but for me, I can’t control the ball.” 4.5 male baseliner using Volkl Tour 9 strung at 63 pounds CP (Wilson Sensation 16)

(Strings normally used by testers are indicated in parentheses.)


(compared to other strings)
Number of testers who said it was:
16 ga. 17 ga.
much easier 0 2
somewhat easier 2 10
about as easy 10 16
not quite as easy 11 6
not nearly as easy 7 1
(compared to string played most often)
Number of testers who said it was:
much better 1 3
somewhat better 6 3
about as playable 8 13
not quite as playable 10 13
not nearly as playable 4 3
(compared to other strings of similar gauge)
Number of testers who said it was:
much better 7 7
somewhat better 13 17
about as durable 9 9
not quite as durable 1 0
not nearly as durable 0 1
From 1 to 5 (best)
Playability 3.1 3.5
Durability 4.2 4.2
Power 3.2 3.5
Control 3.4 3.6
Comfort 2.9 3.2
Touch/Feel 2.8 3.2
Spin Potential 3.1 3.3
Holding Tension 3.9 3.8
Resistance to Movement 4.1 4.0

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About the Author

Greg Raven  is an associate editor for Tennis Industry 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, or through Facebook, LinkedIn, and Twitter. He plays tennis three to five days a week, and is turning into an avid cyclist.



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