Head Intellistring 16L String Review

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

Head's IntelliString is a new hybrid designed to be used with Head's new Intelligence line of racquets. The main strings feature a core of polyamid fibers with wraps of polyolefine ribbons. The crosses are made of polyolefine ribbons. According to Head, it features the ultimate in Ribbon Improved Performance (RIP) technology. The mains are a new RIP Power with ultra thin, durable center core, and a slightly textured surface. The crosses are a new RIP Feel with a coreless ribbon construction. All of these combine to create a one-of-a-kind hybrid string that provides the perfect blend of power, durability and feel with a spin enhancing texture. It is the recommended string for the i.S18, i.S12, i.S10, and i.S6 racquets. Available in 16L gauge in silver/black and yellow/black.


The two coils' mains both measured 25'1" and the crosses both measured 21'9". The main strings' diameter ranged from 1.29 mm to 1.30 mm prior to stringing and 1.26 mm to 1.28 mm after stringing. The cross strings' diameter ranged from 1.26 mm to 1.27 mm prior to stringing and 1.27 mm to 1.28 mm after stringing. A stringbed stiffness of 74 RDC units was recorded 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 69 RDC units, representing a 7% 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 IntelliString 16L added 11.4 grams to the unstrung frame.


Tested for five weeks by 35 USRSA playtesters, with NTRP ratings from 3.5 to 6.0. This is a blind test. The playtesters are sent unmarked strings in unmarked packages. This means they know nothing about the string before they string it and play with it.

As a result, no pre-conceived ideas regarding manufacturers, type of construction, or materials used are able to affect their impressions of the string. Average number of hours playtested was 22.5.


IntelliString is a great all-around hybrid. In fact, it tied with 5 other strings for the second highest overall average of any string we have ever playtested. As you might expect based on it's overall average, it had a few very high scores, but it scored well in every category. While it didn't receive the highest score of all time in any category, it finished second or third in several categories.

The highest rating that IntelliString received was in durability. As a matter of fact, the 4.3 rating ties it for the second highest durability rating in all of our playtests. It makes sense that it should be durable because it is the recommended string for the new i.S10 and i.S12 racquets. Both of these frames have very open patterns (14x17). So, there is lots of room for strings to move and rub against each other. A less durable string might not last long enough for some players in such an open pattern. Final proof of this string's impressive durability is the fact that only 3 playtesters broke IntelliString - one each after 8, 40 and 41 hours.

The second highest rating IntelliString received was in resistance to movement. Only two strings have ever scored higher ratings in this category. Again, this is important when it is the recommended string for frames with such open patterns. If the strings aren't moving as much, they aren't going to wear through and break as quickly.

IntelliString's third highest rating was in tension maintenance. Again, it finished third in this category when compared to all the other playtests we have conducted. As you can see from the bench testing, we also experienced impressive tension maintenance in our office.

The last standout rating IntelliString received was for control. While none of the other ratings stood out as being especially high, the fact that they were all higher than 3 indicates that this string is solid all around. We did have a few playtesters suggest it felt a little stiff and boardy, but the comfort rating was still above average. Finally, we got a few reports of fraying on the crosses, but that obviously did not hurt its durability.


Stringing with IntelliString was a bit like working with a less-scary polyester. It is a bit wiry with pretty strong coil memory. These features create a few kinks during installation. We also got reports of increased friction when installing the crosses. This is because IntelliString doesn't have much of a glossy coating. But, that means you don't feel like you have to wash your hands half way through. Plus, this probably contributed to the high resistance to movement ratings it received.

The fact that IntelliString is a hybrid also makes it a little tougher to install, especially on racquets that only have tie-off holes for one-piece. Finally, several playtesters indicated that it was difficult to cinch up knots because of the wiry feel of the string.

In spite of all these issues, about half of our playtesters indicated IntelliString was as easy or easier to install than other strings. While there were some playtesters who suggested it was not nearly as easy to install, we were surprised that there were so few comments about stringing trouble in the playtesters' comments. We suspect this is for one or two reasons. Either the issues weren't very hard to overcome, or the playtesting made them forget about any troubles they had during installation.


IntelliString's installation ratings weren't as exciting as the playtesting ratings. But, in this case, the string's performance probably justifies any extra effort you might go through during installation. Get a set of this string and try it for yourself. With high marks in Overall Average, Durability, Resistance to Movement, Tension Maintenance & Control, this is probably a string you will want to add to your inventory. So, be sure to send in the coupon on page 25 to get a set for yourself. (By the way, you don't have to cut the coupon out of your magazine. You can just make a copy of the page and send that instead.)


Results from 30 playtesters


(Compared to string used most often)
much better 0
somewhat better 2
about the same 14
not quite as good 13
not nearly as good 6


(Compared to string played most often)
much better 1
somewhat better 10
about the same 5
not quite as good 16
not nearly as good 3


(Compared to strings of similar gauge)
much better 8
somewhat better 23
about the same 4
not quite as good 0
not nearly as good 0


Playability 3.2
Durability 4.3
Power 3.3
Control 3.5
Touch/Feel 3.1
Comfort 3.3
Spin Potential 3.2
Holding Tension 3.6
Resistance to Movement 3.0

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


"The string is one of the best hybrid strings I've played with in many years. The string is more forgiving on the elbow and holds the tension really well." Male serve and volley player using a Head i.S6 MP 102 strung at 65 pounds (Gamma TNT 16)

"A very nice overall string with excellent tension maintenance/ control. It would be a good string to have in stock because it could be used by a wide range of players." 6.0 female all court player using a Volkl C10 Pro 98 strung at 60 pounds (Babolat VS Synthetic Gut/Babolat VS Fiberfeel)

"A better than average string. Power was more than adequate in a super-light frame. Stringbed stiffness was down more than 15% in 14 days." 4.0 male all court player using a Gamma Diamond Fiber C-3.0 MP 105 Strung at 58 pounds (Gamma TNT Pro Plus 17L)

"Very good feel and very lively from the beginning. Appears to be quite durable also." 4.0 female baseliner with moderate or no spin using a Wilson Hyper Pro Staff 6.5 95 strung at 59 pounds (Wilson Sensation NXT 17)

"I love this string. It has a great feel, lots of power and control. It's durable but would need restringing due to loss of tension after several hours of play." 5.5 female baseliner with heavy spin using a Wilson Hammer 6.4 110 strung at 72 pounds (Wilson Synthetic Gut 16)

"Another "eye-pleasing" string. Good string for hard hitters." 4.5 female all court player using a Prince Triple Threat Hornet MP strung at 58 pounds (Tecnifibre 18)

"This particular string is quite comfortable and is great for teaching. There is no doubt that it is meant for a stiff, wide, slow-swinging tennis frame. When I wanted to play seriously, hitting the ball with pace and topspin, I had trouble keeping the ball in the court. I have large swings, good topspin and a rather high kicking serve. From this experience, I feel like this is a niche string and not good for all types of racquets. I will, however, carry it in my shop because I am carrying the Intelligence racquets by Head." 5.0 male serve and volley player using a Prince Triple Threat Warrior 107 strung at 62 pounds (DT 18 mains/Natural Gut 16 crosses)

"Not a bad hybrid, great durability and very easy on the arm. It was a pleasure to use. I was impressed mostly by its comfort and durability. Most hybrids are a little harder on the arm, but not this string. The only complaint I have against it is that the tension started to drop after 4 hours of play and the strings moved more than I am used to. This is a great string for chronic string breakers who prefer a softer feel; it's very similar to the Prince Control Freak although it doesn't have the bite on the ball. Overall, another good string to enter the market. I would carry this string when it comes out." 4.5 male all court player using a Prince Triple Threat Graphite Midplus 100 strung at 67 pounds (Tecnifibre TR Pro 16)

"Very durable. It would be great for string breakers and/or heavy hitters." 4.5 male baseliner with heavy spin using a Head Classic MP strung at 60 pounds (Gosen JC 17)

"A very tough string to figure out. Cosmetically, it looks "cheap". However, I actually used this string in a serious tournament match (and won) and it performed beautifully. Very good sound on impact and the comfort was excellent. In fact, the comfort was good enough to push up my playability rating despite some average scores in other areas. Despite the smooth coating, this string obviously has significant texture, but I didn't feel spin potential was anything special. Another strange thing with this string was that the cross strings showed fraying very quickly, while the mains were pristine. This is totally opposite from my usual experience. This string appears to be very durable. With great comfort, this is an odd combination. I don't really know what to make of this string." 5.0 male serve and volley player using a Gamma Big Bubba Tour 131 strung at 38 pounds (Gamma Synthetic Gut 17)

"Pretty good string if priced right. It did have somewhat of a spongy feel, but still played well. Although it lost tension initially, it stabilized and still played OK." 5.0 male all court player using a Wilson Hyper Carbon Pro Staff 5.0 stretch Midplus strung at 58 pounds (Gamma TNT 16)

"I experienced a high initial tension loss, yet the string played as though it was strung much tighter. I can't explain it. Normally, I can't control a string at 54 pounds. It had surprisingly good feel, but exhibited no specific outstanding characteristics. Not a bad string; just not a great or particularly outstanding one." 4.0 male all court player using a Pro Kennex Kinetic Charged 15g strung at 64 pounds (Gosen OG Sheep Micro JC 17)

"This string strung up tight and held its tension well. Very little string movement. I thought I would have gotten more spin out of this string than I did." 5.0 male all court player

"This string is quite durable and seems to hold up well in racquets with wide string patterns where breakage is a real problem." 4.5 male all court player using a Volkl C-9 Pro 98 strung at 62 pounds (Laserfibre Supreme 17)

"Although it was slightly more time consuming to string my racquet, the above-average playing characteristics, plus excellent resistance to movement features of this string make it a desirable product." 4.0 male all court player using a Cayman Pro Talis II 110 strung at 60 pounds (Cayman Synthetic Gut 18 DT)

"I liked this string more than I thought I would. It seems to perform better at higher tensions when I hit with another racquet at a lower tension, I hated the way it felt. I was surprised by the durability, feel, and tension holding." 5.0 male all court player using a Gamma Diamond Fiber F-9.5 strung at 68 pounds (Leoina HiTech 18/ Babolat VS 16)

"Very durable and held the string pattern well. I found it to have a stiff feel." 5.0 male baseliner with moderate or no spin using a Head Pro Tour 280 97 strung at 57 pounds (Prince Synthetic Gut 17)

"The cross string had lots of coil memory. Overall, a stiff string combination that lost my enthusiasm due to its lack of comfort." 4.5 male all court player using a Volkl C-10 Pro Tour 93 strung at 60/58 pounds (Forten Dynamix 16)

"Ouch! This is a stiff string. I guess I'm spoiled by all the softer strings out there." Male player using a Prince Triple Threat Warrior OS 107 strung at 62 pounds (Prince Power Glide 17 or Wilson NXT 17)

"Not a very responsive string. I can see it playing well at lower tensions in the lighter, larger "high-tech" frames. It felt mostly stiff and dull in a racquet designed for a bigger swing. Played very quiet and similar to Head IntelliString." 5.0 male baseliner with heavy spin using a Wilson Hammer 6.4 Power Holes 95 strung at 49 pounds (Prince Synthetic Gut Soft 16)

"The playtest string took a little longer than usual to install due to its wiry nature. Initially, I thought the string was somewhat stiff playing, but after just a little playing time, I found it to have a crisp, clean feel. The string provided good control with more than adequate power. I did notice a larger degree of fraying on the cross strings than I normally experience since I hit a flat ball. I wonder how this string will hold up for heavy topspin hitters. I will add this string to my inventory - I hope it comes in a variety of colors since the color of the test string did nothing for the appearance of my racquet." 4.0 male baseliner with moderate or no spin using a Prince Triple Threat Stealth 100 strung at 57 pounds (Prince Sweet Perfection 17)

"Very similar to Head IntelliString, which I tested for Head in their new racquets. Just a bit stiff and boardy for my game but understandable being a hybrid." 5.0 male all court player using a Yonex Ti 450 110 strung at 60 pounds (Prince Synthetic Gut with Duraflex 16)

"I would not carry this string in my shop because I have nobody who needs this much durability at the expense of playability and feel. Plus, the colors reminded me of the cheap string I used when I was practicing my stringing skills in high school. I could not wait to cut this junk out!" 6.0 all court male player with heavy spin using a Prince Triple Threat Graphite 107 strung at 78 pounds (Prince Sweet Perfection 16)