Head FiberGel Power Tennis String Review

Reprinted with permission of the United States Racquet Stringer's Association

HEAD FiberGEL Power 16 is a multi-filament, single-wrap string that incorporates two "twin gel" fibers within the core, and a special polyurethane coating. FiberGEL Power is the newest member of the FiberGel family. The original FiberGel 16 garnered a top-ten finish among synthetic strings in our 2002/2003 String Survey Members' Choice Awards (see the poster in the December 2002 Racquet Tech), even though it it was at that time still fairly new to the market. Perhaps not surprisingly, FiberGel 16 was one of HEAD's best-performing strings in USRSA playtests. So confident is HEAD of their new power string that they sent a free set to every USRSA member in the U.S. with the August issue of the magazine.

The key difference between FiberGel and FiberGEL Power lies in the core. Where FiberGel had a monofilament core with a wrap of gel fibers, FiberGEL Power's core is made up of more than 500 multifilament DuPont fibers, bundled with two larger twin-gel fibers.

HEAD matched the characteristics of the multifilament fibers with those of the twin-gel fibers to produce more resiliency and power. The twin-gel fibers also act to dampen vibration for more comfort. HEAD uses a special manufacturing technique that utilizes the elasticity of the fibers to create a softer string, which they say contributes to both feel and control.

The polyurethane coating and outer DuPont wrap reduce surface friction and control tension loss, for a durable string that is easy to install.

HEAD FiberGEL Power is available in 16 gauge in "natural" (actually a light yellow-on-yellow color). It is priced from $9.00 for sets of 40 feet.


We tested the 16-gauge HEAD FiberGEL Power. The two coils measured 41 feet 11 inches and 41 feet 11.75 inches. The diameter measured 1.33 mm to 1.35 mm prior to stringing, and 1.28 mm to 1.29 mm after stringing. We recorded a stringbed stiffness of 80 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 73 RDC units, representing a 9% 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% tension loss. HEAD FiberGEL Power 16 added 10.8 grams to the weight of our unstrung frame.


FiberGEL Power was a breeze to install, even for a synthetic string. There was more than enough length and, like the original FiberGel, it elongates during stringing to make the coil seem even longer than it measures. There is little coil memory, and the combination of FiberGEL Power's smooth surface and a light lubricant enable even hard weaves to glide right through. The multifilament core does make FiberGEL Power feel softer than the original FiberGel, so blocked holes are more challenging, but only very slightly so. Cutting the end of the string to form a "plastic awl" solved all problems for us in this category. The only caveat comes from the elasticity of FiberGEL Power, which makes it a bit more difficult to pull all of the slack out of the tie-off string when cinching up knots.

FiberGEL Power's ease of stringing is amply shown in our playtest results: No playtester broke his sample during stringing, one reported problems with coil memory, two reported problems tying knots, and none reported friction burn. No wonder 10 out of 26 of our playtesters rated FiberGEL Power easier to install than other strings.


The scores indicate that our playtesters felt HEAD made huge improvements in Playability, Power, and Holding Tension in FiberGEL Power compared to the

original FiberGel, and as indicated above, the original FiberGel scored very well indeed. FiberGEL Power also received better ratings for Control than the original FiberGel, and virtually identical ratings for durability. In other words, they appear to have created a better string without sacrificing durability.

When compared to other strings we have playtested, FiberGEL Power still came out with great scores for Playability, Power, and Holding Tension. Of these, the Playability rating was particularly good, with a score that places it among the top strings we have tested. Even in a traditionally tough category, where playtesters compare playability of the test sample against the string they use most often (that is, their favorite string), FiberGEL Power received significantly better scores than is usual for playtest strings. Our playtesters also gave FiberGEL Power better ratings for durability than other strings of similar gauge.

Seven playtesters broke the sample string -- two at about four hours, one at seven hours, one at 15 hours, one at 27 hours, one at 67 hours, and one at 85 hours. Average playtest time was just over 25 hours.

The Testers

Tested for five weeks by 26 USRSA playtesters with NTRP ratings from 3.5 to 5.5. These are blind tests, with playtesters receiving unmarked strings in unmarked packages, to reduce preconceptions and biases regarding manufacturers, type of construction, and materials. Average number of hours playtested was 25.2.


Our playtesters were clearly impressed by the ease of stringing FiberGEL Power 16, and in their comments many mentioned the same strengths that HEAD has tried to build into FiberGEL Power.

There must be many players looking for a relatively durable and comfortable string with power and playability, which holds tension well and has no negative surprises. HEAD FiberGEL Power even received higher scores than the original FiberGel in the 2004 USRSA String Survey Members' Choice Awards, so if you are one of those already using the original FiberGel, you owe it to yourself to give the new version a try.


"This is one of the best strings I've ever hit with. Everything felt solid. I felt as if I had the rare combination of increased power and better feel. All hits even sounded good. I would recommend this to anyone looking for an all-around premium string." 5.0 male all court player using Wilson Triad 6.0 strung at 62 pounds CP (Wilson Sensation 16)

"This is a good-playing string. Its power allows the ball to trampoline off the string, and it is sustained. I would like to know what it is and the price." 4.0 male all court player using Gamma Diamond Fiber 4.5 strung at 65 pounds CP (Gamma TNT 17)

"This is a great string. It held tension well and was comfortable to hit with. The playtest sample appeared to have significant pop when hitting. Easy to string with on my lockout machine." 4.5 male serve and volleyer using HEAD i.X6 MP strung at 64 pounds LO (HEAD Intellistring 16) "What a relief to have a string that is neither natural gut nor poly. Really nice ease of stringing. The string was stretchy enough that I didn't feel that my knots were as tight as they should have been. On court, it felt at first as if it had too much power, but this sensation disappeared quickly, and I was able to bang away with great effect. The strings started moving almost immediately, but they settled down after about 45 minutes and played fine from that point on." 4.0 male all court player using Wilson ROK strung at 57.5 pounds CP (Pacific TourGut 16)

"The durability of the test sample was better than most strings of similar guage, but the biggest asset of the string was its ability to keep its tension." 5.0 male all court player using Prince More Game MP strung at 62 pounds LO (Prince Lightning XX 17)

"I would consider playing with this string if it came in a thinner gauge. I was able to hit crisp shots while still having good feel on my volleys. Even at such a high tension, it never bothered my arm at all. The string did fray a bit, but I assumed this was due to it being a multifilament. After a significant amount of time there was a loss of tension." 5.0 male serve and volleyer using HEAD Liquidmetal Radical MP strung at 68 pounds LO (Wilson NXT 17)

"This is a nice string. It is not outstanding in any one category, but I am impressed with the tension-holding and resistance to movement. I would recommend it to my customers." 4.5 male all court player using Volkl Tour 10 MP strung at 60 pounds CP (HEAD Intellitour 17)

"Overall a very good-playing string as far as decent power and durability. I would definitely purchase it if reasonably priced. I also liked the color." 5.0 male serve and volleyer using Babolat strung at 54 pounds CP (Babolat Xcel 16)

"This string lost a bit of tension in the first five or six hours, then it felt great. I liked the durability, but I am used to a thinner string so I sacrificed some touch and feel. I would recommend this string." 5.5 male baseliner with heavy spin using Babolat strung at 62 pounds LO (Babolat Super Fine Play 17)

"Overall, this was a good-quality string. Depending on the pricing, I would encourage higher level players to try it." 5.0 male baseliner with moderate spin using Wilson Pro Staff 6.1 strung at 60 pounds LO (Wilson Sensation 16)

"Good multifilament string with less vibration than usual. I normally can't stand not having a small dampener in, but I actually liked this string without one." 5.0 male all court player using Wilson Pro Staff Tour strung at 55 pounds CP (Wilson Extreme Synthetic Gut 17) "This string works adequately from the baseline, with good power when flattening out the ball and serving. Control was an issue on volleys; specifically the directional control wasn't there for me, and the string lacked feel on low and touch volleys. All in all, a fair string if the price is reasonable." 4.5 male serve and volleyer using Fischer Pro No. 1 strung at 62 pounds CP (BDE Rallye 16)

"Overall, a really nice string, comparable with Wilson Stamina and HEAD FiberGel. I really liked it. Crisp volleys, good power on groundies, potential for spin on serves. I'd use it!" 4.5 male all court player using Wilson H5 strung at 62 pounds LO (Wilson Stamina 16)

"This string was more playable than most durability-oriented strings, but I still never felt comfortable playing with it. This would be the type of string to recommend to a person wanting to come back down from a aramid hybrid. Even though this string might not feel the best, it would last a good amount of time." 4.5 male all court player using Volkl Tour 8 strung at 62 pounds CP (Gamma TNT 16)

"Solid string. I would buy it." 4.5 male baseliner with heavy spin using Dunlop 300G strung at 60 pounds LO (Babolat Ballistic Polymono 16)

"Of the playtest samples I've tested, this is probably the easiest to string. From a player's standpoint, there's nothing special to mention. It seems to be an average string in all categories." 5.0 male all court player using HEAD i.radical OS strung at 60 pounds LO (Gamma Synthetic Gut 16)

"Not a bad string, but it does not compare to what I use now. I would not switch to it and I would not recommend it to serious players." 3.5 male all court player using HEAD i.radical MP strung at 58 pounds CP (Luxilon Ti-Mo 18)

"Initial two to three days of test playing produced sore elbow and wrist. Very good string that maintained its tension with very little string movement and no buzzing sounds. Stringing the racquet was not difficult with this string. Lots of extra string -- 44 feet in my coil. Knots tied cleanly and easily. After four days of stiffness, the tension loss made the strings a little more enjoyable. I would recommend this for excessive string breakers and college players. I would not recommend it for ladies below 4.0 rating or non-heavy hitters." 5.0 female baseliner with heavy spin using Dunlop 200G strung at 60 pounds CP (Dunlop Max Comfort 16)

"Average multifilament. Gets poor marks for durability. Doesn't generate much power. It better be inexpensive, because it's not worth much. At least it's easy on my arm, and it's a breeze to string this stuff." 4.0 male serve and volleyer using Prince Triple Threat Bandit strung at 63 pounds LO (Gosen OG JC 16)

"This string did not play well. From the beginning, it felt dead and shots were difficult to control. I thought it would play better after a few hours, but nothing changed during the entire playtest. Durability was the only positive point for this string." 4.0 male baseliner with moderate spin using Pro Kennex Kinetic Pro 7G strung at 68 pounds LO (Babolat Ballistic Polymono 17)

"I felt this string held tension well, but did lack the feel and touch of some of the other test strings. While there were no visible signs of wear, the playability was just average. I suggest this to be a string for string breakers looking for minimum feel." 5.0 male all court player using Wilson Triad 6.0 strung at 60 pounds LO (Wilson NXT Tour 17)

"A rather unremarkable string. Played similar to a poly." 4.0 male all court player using Prince Thunderlite LB OS strung at 60/57 pounds LO (Wilson Sensation 16)

"Very easy to string, but it was just an average string for power and control. I didn't like it compared to my normal string." 4.5 male all court player using Wilson Pro Staff 6.1 Stretch strung at 61 pounds LO (Wilson NXT 17)

"The string moved excessively with my topspin. I had to keep moving the string back into position after every point. I kept hitting the ball long because I couldn't produce enough spin to keep it in. The string is better suited for lower-level players." 4.0 male baseliner with heavy spin using Wilson Triad 3.0 strung at 60 pounds LO (Luxilon Alu Power 16L)

"After four hours, the string broke during mini-tennis warm-up. 'Nuff said'." 5.0 male all court player using HEAD Prestige Classic 600 strung at 61 pounds CP (Gosen Polylon Ice 17)

"The test sample broke after about four hours, so I didn't really have time to evaluate it." 3.5 male baseliner with heavy spin using Wilson Hyper Pro Staff 6.1 MP strung at 67 pounds CP (Luxilon Big Banger Alu Power 16L)


Results from 26 playtesters


(Compared to string used most often)

much easier
somewhat better 7
about the same 16
not quite as good 0
not nearly as good 0


(Compared to string played most often)

much better 1
somewhat better 3
about the same 11
not quite as good 11
not nearly as good 0


(Compared to strings of similar gauge)

much better 1
somewhat better 11
about the same 9
not quite as good 2
not nearly as good 2


Playability 3.6
Durability 3.4
Power 3.5
Control 3.4
Touch/feel 3.1
Comfort 3.3
Spin Potential 3.0
Holding Tension 3.5
Resistance to Movement 3.2

KEY: Respondents ranked string from a possible low of 1 to a high of 5. Median value is 3. Values represent average overall ratings.