Ask John

Do you have a stringing or tennis related question?  Ask your question in the comments box below.   Stay tuned to this page for new questions and answers!

Questions will be moderated and answered within 3 business days.

Posted on May 6, 2019, in Good News!. Bookmark the permalink. 57 Comments.

  1. Dear John 🙂
    Is there a Taiwanese String manufacturer or other from Japan to make me a batch of Strings according to my specs you can recommend. The material and design is unique but not willing to share it at the moment, regards, David

    • David, what is the patent status of your design? There are a lot of really good string companies but they may require some sort of NDA agreement.

  2. Hi
    My friend Brooke gave me your info. I’m in a diff state but am looking for suggestions for string? I have one heavier racket that I use for power and need string suggestion and then another lighter racket for control that also needs to be strung? Thoughts are appreciated. Angie

    • Thank you for the question, Angela!

      How do you decide on which racquet to use? Is it based solely on your opponent? Are both racquets the same, but one has been modified, or are they different? A heavier racquet will contribute to power and control through the inherent stability of the mass. An answer to your question, without regard to my questions, would be to use a high elongation string, i.e., MonoGut ZX orZX Pro (thinner)
      Tecnifibre Triax or other multifilament constructed string at moderate tension. For the control racquet, I would suggest the same string material but at a slightly higher tension. The string bed stiffness is a critical piece of information, so let me know what stringing machine your stringer is using.

  3. We often hear that a player should use the heaviest racquet they can swing without excessive fatigue. What do you think? Is it better to think in terms of static weight or swingweight?
    What would be your swingweight recommendations for the majority of amateur players (for example at the 4.0 or 4.5 level not particularly strong physically)? What is too high or unhealthy?
    Also, if we take two rackets with different static weight and swingweight, which one is “better” or healthier? Or is it only a question of personal feel?
    For example :
    Racquet 1 : 305g balance 31 cm SW 295 (unstrung)
    Racquet 1 : 305g balance 32 cm SW 295

  4. Hi John,

    I have recently been dealing with minor tennis elbow and my doctor gave me exercises to strengthen a variety of muscles in my arm. I currently use various Clash racquets but sometimes I pick up a Pro Staff 90 because that racquet feels great and helps me keep my wrist loose as it’s weight takes over the swing as long as you have good technique. My question is regarding staining the Pro Staff 90. I have tried with a full bed of multis at 48lbs and did not like it. I also tried Velocity MLT at 48lbs in the mains and Gamma Glide in the crosses at 50lbs. I like the feel a lot better but was wondering if it would be ok to go even lower on tension, specially using Velocity MLT on mains and Glide on the crosses. In the clash I typically use Hyper G soft 18g at 44lbs and that racquet feels soft and plush. Recently I also used Babolat Synthetic Gut in the mains of a Prokennex and liked it as well. I guess after reading your many articles about avoiding polys if possible have made me wonder my stringing a lot more. My issue is that I don’t like multis by themselves because they don’t snap back. Would a synthetic gut mixed with an MLT be the way to go? Or do you think the MLT with the Gamma glide is the safest for the arm as well as best scenario for snapback? Cheers and will subscribe to your podcast later this evening!

    • John Gugel
      Fri, Nov 4, 4:53 PM (1 day ago)

      to WordPress

      Jonathan, thank you for the message! This a situation that affects many players, and our first reaction is to go to a full set of MonoGut ZX Pro (17ga) in either the Clash or the Pro Staff. This material likes slightly higher tensions, so anything between 50 and 60 pounds works for most players. Lower tensions have a tendency to be too powerful! If you want to stay with the Hyper G setup in the Clash I would suggest you add a little swing weight. We will take about this in an upcoming podcast, too! Thank you!

  5. Steven Klurfeld

    Hi John,
    Do you have a searchable database which ranks strings
    Based on % elongation; or does one exist?

    Also- can we assume that as the gauge of string gets thinner the %
    Elongation grows?

    Thanks as always for your efforts

    • Thanks for the message, Stephen! We have been collecting this data for for over 30 years and it is available on the “String Power Potential” tab on this site. We have tested 16 gauge that has slighty higher elongation than 17 but that is not typical. You can sort this data by brand or power potential.

  6. Hi John,

    Are you sure that your data for genesis black magic 16 is accurate? Black magic 17 has 1/2 the power potential of the 16 according to your database. thank you!

  7. Hi John,

    I was impressed by your approach of recommending rackets based on UTR. I still can not believe that racket & string selection is far way from being an exact science despite all the available player and performance data in hand.

    That being said, my son is a 14 year old, (5′ 6, 110lbs) Tennis Europe player with a 7.50+ UTR, playing with a Babolat Pure Aero Team (285g) and he is looking for more power, thinking about a Babolat Pure Strike 16×19 (305g).

    What do you recommend especially in terms of racket weight? By the way, he’s using Kirschbaum Pro Line Evolution Blue monofilament strings around 50-49 lbs). We may not be coming to Florida to your shop anytime soon because of the pandemic, but I would appreciate if you share your know-how with us.



    • Thank you for the message, and thank you for including the important data on your son!

      There are a couple of additional data that is important if you have it, and that is string bed stiffness and swing weight. With the information we have, we would suggest trying the Babolat Pure Drive VS in addition to the Strike. Overall weight in the 320-gram range with a swing weight of 320 kg/cm^ would be good.

      If a change from Babolat is considered try the Head Prestige Tour.

      We would also suggest trying a non-polyester string if possible. I know it sounds a little radical but polyester string even at low tensions does not offer much energy return. Tecnifibre Triax or RPX is a good multi-filament and Ashaway MonoGut ZX or ZX Pro is a very good non-poly mono-filament.

      I know, it is too bad we can not travel freely right now. We would be happy to set up a racquet, with data, if you could send one.

      Please let us know if we can help.

  8. Steven Klurfeld

    Hi John,
    Three quick questions:

    1. In a recent podcast I think you stated that tennis elbow is not caused by the frame, but could be caused by the strings, or Bad technique.
    Is that correct?
    A frame with an RA of 70 isn’t more likely to be less arm friendly
    Than one with an RA of 52?

    2. If you wanted to add control to a frame, hoe much and
    Where would you add the weight?
    3. There seems to be a push away from lead toward tungsten
    Weight tape.. do you think the fears of lead contact are warranted?

    Steve K

    • Steve, thank you for the message! You ask some very valid questions that I wish more players would consider.
      1. We have a few players suing the Wilson Ultra 100 which has a RDC (RA) stiffness of 72 and by adjusting the string bed stiffness (tension and support) we can create a very comfortable effective stiffness. That stiffness may be different for other players of course but will normally be less than 30. So, your assessment that a 72 RDC is more likely to be less arm friendly is generally correct.

      The second part is also interesting in that while the Wilson Clash is very flexible it has an RDC stiffness of about 50-51 and the Head Speed has a RDC stiffness of 51-52, however, using a different testing method the Wilson Clash will be 25 and the Head Speed will 50-51!

      2. Control can be a function of weight as you suggest but string bed “accuracy” contributes as well. So, again, the more consistent the stringing and support is the more accurate the ball launch can be. Stability of the racquet is important and adding weight at the mid point os the sides of the head is the most effective location to increase stability. We would 5-6 grams total at that location and add a similar amount to the rear of the racquet.

      3. I don’t believe lead tape is an issue less you decide to eat a few rolls of it! We are cautious of course and I would suggest that wearing exam gloves and wiping the tape after installation with acetone would mitigate any harmful affects.

  9. Hi John,
    My question concerns spin and string type. In my mind there are 2 competing ways that string can impart spin on the ball.
    A rough/textured/shaped string can grip the ball, and as you brush up or down, the player can impart increased spin. So this would suggest getting a string like “Babolat fine play rough” which has a textured string would be useful
    The Second way is to have a smooth polyester string which allows the strings to grip, but then slide back in position, sling shotting the ball, and as the strings return to their position, spin is imparted onto the ball.
    We have been told that the advent of polyester strings are what have allowed modern players to produce revolutionary levels of spin.

    Is there data which shows that all things equal,(racquet/tension/swing path/etc) polyester strings will impart more spin than textured string?
    Sorry for the long winded question
    Steve Klurfeld

    • Steve, that is a very good question and one that has been discussed for years and probably will be for for a few more years.

      Spin is caused by friction!

      If there is little or no friction the ball will simply slide across the string bed with limited rotation. So, the easiest way to create friction is to open up the spacing between strings, all strings preferably! However, there are a few not so wonderful things that will happen: One, the strings will probably break more frequently than the player would like, and two, the control associated with spin may be diminished.

      Moving strings is another way to generate a little more rotation but “moving” and string deflection must be “tuned” to the same frequency to produce spin. This is OK but only lasts a short time.

      Perfectly smooth strings may exhibit more string to string friction and not move as readily as a string with a very fine texture, such as Yonex PolyTour Pro, for example.

      Polyester strings, typically, are a very “low power” component and as such require greater effort (swing speed) to get the ball to go as deep with spin. So the requirement to hit the ball hard with polyester string can create more rotation!

      Thanks for asking!

  10. Hi John, I was interested in the Prince Original Graphite 107. Would I be able to purchase the Racquet from you, have it set up to your specs and set to me. The again, do you think it a fools errand to purchase such an old Racquet and make it work. I appreciate your feedback.


    • Hi, Richard, and thanks for the message! We do not have any 107’s and finding one in any condition would be tough! That racquet was a very good one and I certainly wish they were available

  11. Hi John,

    Why don’t racquet experts talk more about shortening a racquet as a possibility to get more control? The usual response I hear from most is tighten the stringbed or use poly strings.
    I started playing tennis as an adult 4-5 years ago. Since I decided to play tennis regularly and started looking for a higher quality racquet, I’ve been seeking more control as I have very little issue generating my own power.
    After trying more than a bunch of racquets and strings over these years, I got the courage to experiment, as others have done, with a shorter length racquet. I didn’t want to cut any of my current racquets as this was the first attempt, so I bought an inexpensive 26″ junior racquet. It’s very light in stock form, but I knew after a few hits with it that I should have tried a shorter racquet sooner. I have since added weight (at about 12 oz now, and 11 points head light) for stability and comfort, and I play much better. I now have the confidence to take a full swing and feel like I can actually develop my game far better than before. Far less balls go long, and if a ball does, I can figure out what to do better on court.
    Furthermore, my arm is feeling better. Serving has been far less stressful on my shoulder, and my elbow is nagging me less and less. I’ve heard a few of your podcasts, and it’s evident you care about the health of players, especially when it comes to polyester, and which is why I’m asking you first.
    I know there’s a stigma to shorter racquets. I experienced it when I considered a “junior” racquet in my own mind and with others. Initially, I felt a little strange, wimpy maybe, walking around with a junior racquet, even with the added weight on the court. Also, I took different racquet (26.5″) to my stringer today, and, basically, he was laughing at the idea. Sometimes, for better or worse, marketing really works i guess?!
    Nevertheless, the results are undeniable to me. And with the added benefit of my arm getting better, I don’t see myself using a 27″ racquet anytime soon as my top choice. Time is needed to adjust, and I don’t have the reach I once had, but gains far out weigh these changes. FYI, I don’t know where I’ll land on length, but somewhere just beyond 26″ is my guess at the moment.
    Now considering this topic, I think we can keep racquet and string companies aside at the moment too? To me, a customizer that uses this option as a possible solution could, of example, give someone a shorter racquet to try before cutting a racquet. Or take off the buttcap, and make a faux buttcap at the base in order for a client to get an idea of how it would play. Yet, basically, I only hear about this option on the internet deep in a tennis forum.
    I see this as a clear, relatively simple, and safe solution that is under-utilized to gain more control. What’s going on? What are your thoughts?

    Thanks in advance!


    • Hi, Brandon! I thought I had replied to your post but I guess I messed up! Sorry! Several years ago we did a significant number of racquet length reductions. These reductions were done to accommodate physical size issues not so much maneuverability, but I am sure that would be a benefit!

      I know I had a few other comments so I will try to find them and post them as soon as I can.


  12. john, i still,use the original howe flex four. i see that u have improved on it. my nos are usually higher than ref. tension. coul i send it to you to maybe upgrade it and if so Cost$$
    thankyou ,

  13. Dear John,

    I noticed in your ‘By the Numbers Post’ that you say for twistweight , “the higher the better” … however, if one is to increase swingweight to a value of above 340 grams, would a higher twistweight value of 14+ be detrimental to both manoeuvrability and spin potential?

    • Lance, thank you for the very good question! Twist weight can be a function of added weight or simply a wider racquet head. The farther from the neutral axis of the racquet the weight is the more affect it has. For example a Prince Phantom Pro 100 has a wider head than, say a Wilson Blade so the natural twist weight is 252.3 with a swing weight of 324 compared to the Blade that has a swing weight of 337.0 and a twist weight of 233.8.

      As swing weight increases the maneuverability may decrease a little but the “momentum” should increase the spin potential if the player is strong enough to move around the swing weight.

  14. Steven Klurfeld

    Hi John, I’ve enjoyed my Yonex DR98,(16×19) pattern strung at 51 lbs. I recently started using the HDpro 97.(18×20). and 50 lbs feels much tighter. By how many pounds should I drop tension on this tighter string pattern to have the strung bed feel more similar to what I had?

    • RacquetQuest

      Steven, if everything else remains the same a 18% reduction in tension setting would be where I would start.

      Because of the more open pattern the 16×19 string bed will include some slippage that may not occur on the 18×20 so they may never feel exactly the same.

      Let me know how it feels!


  15. hi john, what do you think about the pre-stretch on the TTSM. do you still use the pre-stretch? is it always 15lbs mains and 20 lbs crosses? can i enable the pre-stratch by leveling down?
    thanks in advance


    • RacquetQuest

      Simon, sorry for the delay! I do use pre-stretch on this machine dependind on the string and racquet. I use 15 and 17 for most racquets. This pre-stretch function is very precise and I find it helpful.

      I am not sure what you mean by”leveling down”.

      Keep it up!


  16. Hi John! Love your webpage and the informative content! since a few days i am a proud owner of a true tension stringing machine! bought it from a lady, she worked for Fischer Austria as a full-time stringer in the 90’s and strung about 25.000 racquets with that beauty. your video about the stringing was very helpful for me, but i still have some questions and in a search for the manual. i can’t find anything on the internet. you might have some info material to share?
    Thanks in advance

    Simon from Austria

    • RacquetQuest

      Simon, thank you for the message! These machines are simply the best! We have, currently, five of them and I just acquired one of the very first machines ever made! It is absolutely brand new. I still marvel at the functionality of the machine. I will look around for a manual but I am not sure I have seen one for several years. I will let you know! John

      • Thank you for your quick reply, stringing with the machine is so much fun. Feels like craftmanship. I will listen to your podcast this days, so i can learn some more…
        Keep up the good work!

  17. Louis DeLaPena

    Hello John!
    My question is: I start my mains by clamping and backing up with starting clamp on inside then proceed to string 3 mains opposite of that, then start side with starting clamp and fixed clamp. When I get to second hole and try to clamp, I can’t get close enough to so there is space between racquet and where I clamp. Should I continue doing it this way? Or try different starting method? When tension next one, will that self correct?
    Thanks for any advice!!


  18. Hi John, Thanks for all you write about, and your expertise. I recently moved to the 97 Vcore Pro HD, and love the weighting balance and stiffness. I’m looking to retain some of the ball pocketing from more open patterns, is there a string and tension you might recommend I use, without losing control?

    • Steven, sorry for the delay! This is a very dense string pattern so the string will need to a be high eleongation model to acheive the “pocketing”you want. Depemding on how many hours you want the string to last I have had good feedback with Yonex Rexis both 125 and 130 gauge.

      Our demo is strung with a pre-production PEEK fibre 1.25mm from Victrex at 55 pounds with a DT of 37 and the reponse has been very favorable.

      Let us know what you try.

  19. Hi John!
    Question about tying Poly on gut. I know this is a no-no. I was thinking, if i I had a situation such as this, could I use a small piece of electrical tape and wrap around the gut where I would tie knot. Do u think this would suffice in protecting the Gut when tying knot?
    Thanks for any advice!!


    • Louis, thank you for the question! I would not rely on tape to protect the natural gut against the polyester knot. The best option is to tie off on a cross string of the same material. You can prepare the tie off hole before stringing. If this is not possible a short piece of protective tubing can use on the gut at the tie off location if the hole is large enough. Then tie the polyester off on the tubing, not the gut material. I would sure try to find a good cross string to tie off on, though!

      • Thanks for the advice! Probably should have some tubing in my tool arsenal for this reason and other situations. I guess I would rather use the tubing solution rather than comprising a hole not made for tie off. At least on a customer racquet, though if done with care shouldn’t be an issue.
        Thanks again!!

        • Good idea, Louis! Did you know that many racquets have grommets large enough to accommodate two (2) stings easily? Take a look at the racquets you have and you may see an extra large grommet on the sides near the top and bottom.

          • Thanks John! I have noticed some are larger. Since I don’t string with gut very often, I’ve never had to improvise and preparing for situations before they actually occur, especially with advice from experts!!

  20. Hello! I use an offset tool on outside of racquet to protect string when starting crosses. I see many stringers use starting clamp on outside with no protection when starting mains. I would think you need to protect string from starting clamp when starting mains this way. Thoughts? Thanks!


    • Hi, Louis, and thank you for the message! You are doing the right thing by not clamping too close to the grommet where the string must bend.

      Some stringers have never done this and many have not had a problem they were aware of so it continues to be their procedure.

  21. John — In hybrid stringing, players are hoping to get the benefits of the differing characteristics of two strings. But what are we trying to accomplish, and what are we actually accomplishing, in terms of string bed stiffness? For instance, when I string a natural gut in the mains and a poly in the crosses, should I be stinging the gut relatively high and the poly relatively low, as I would in full beds of either? Say I string the mains at 57 lbs. and the crosses at 42. Even though the strings have very different inherent stiffness ratings, does that disparity in tension have unintended consequences on the string bed stiffness, and therefore on performance?

    • RacquetQuest

      Hi, Jacob and thanks for the message.

      Individual strings with different stiffness characteristics will produce a string bed stiffness and that is what the ball, and body, feel. The shorter the strings the tighter they will feel but there are normally more cross strings than main strings so the ratio is important.

      In terms of actual accomplishment it would be better measured by tension stability due to the more elestic string offering a restoring force to the stiff or lower power string.

      In some cases the SBS of a hybrid will be greater than a full polyester. I would not recommend the wide ratio you reference 57/42 and in fact would start with the same tensions. Polyestr can feel quite soft

      That is a long way around your question so I hope it helps.

      • That is helpful. But I wonder under what circumstances a polyester can feel quite soft?

        • Jacob, you may get two replys on this question. The most common circumstance is that the racquet has distorted and recoved rendering the string bed stiffness lower than expected. The stiff string does not have much elongation so not much “tension” so the racquet after stringing will change shape a little to try to remove built up stresses. This change can decrease SBS a lot therefore the soft feel of stiff string. However, When the ball is hit really hard to generate depth and maybe some spin the stiffess of the string bed inceases substantially, then retracts after impact. It is that increase in stiffness that may cause discomfort.

  22. stringweaver

    Hi John,
    In your stringing video “Standard String Process” you indicated that you have used string spreaders for many years to reduce friction when weaving the crosses. The tools you use do not appear to be available any longer, though there are two other string spreaders currently on the market–the StringWeaver (from and the MK2 (from Despite their obvious benefits, string spreaders have not been widely adopted by racquet stringers. Why do you suppose that is? I look forward to your opinion.

    • RacquetQuest

      Dennis, as far as I can tell most stringers don’t want to take the time to add a “step” to their technique and their customers are perfectly happy with the result.

      • RacquetQuest

        Dennis, I have some additional thoughts on your question and in fact I have written about them on several occasions;

        Until the customer has experienced the difference a properly strung racquet can make there is no incentive for a stringer to try to do better becasue it is not going to be expected by the customer.

        A few years ago a stringer was concerned they were loosing business to big box stores. This was business they once had. I asked what they did differently than the big box and they could not come up with anything definitive! They should have been doing a better job educating the customer.

        So, if the customer doesn’t know a better playing racquet is possible there is no incentive to change the way it is being strung.

        • Dennis Sadowski

          John, thank you for your additional thoughts on the subject of using string spreaders. My feeling is that by using a spreader they not only get a better result but they make the job easier and more pleasant for the stringer. After all, stringing a couple of 18×20 frames with sharped edged poly is quite literally a pain in the finger tips. The gap created by the spreader certainly makes weaving and pulling the crosses easier. String spreaders only take a few seconds to mount and remove, so they don’t add time to the job, and in fact may reduce the overall time. If stringers don’t use a spreader to benefit their customers, they should at least consider the benefits to themselves.

          • RacquetQuest

            Dennis, thaks for the response! We have tried for years to teach “best practices” but it has not worked as far as I can tell. Most stringers have not been exposed to these practices and have no idea the advantages, and I said before, until the customer demands better it is not, in my opinion, going to happen.

            It is too bad…

  23. What are your favorite strings and why?

    • RacquetQuest

      Sig, here are some of the strings my clients and I like:

      Babolat VS Touch and VS Team – Natural gut that offers the benefit of power and comfort.
      Ashaway MonoGut ZX and ZX Pro – PEEK material that offers very good durability and arm/body protection.
      Yonex Rexis – Nylon multifilament is a will made multifilament that offers great playability with better than average dudability for a multifilament
      Tecnifibre HDX Tour – Nylon multifilament bundled with polyurethane for great control potential but lacking some in durabilty.
      Head Reflex MLT – A technical multifilament with slighty higher durability than most.

      We don’t promote polyester based string for most players but we have found that Head Lynx offers a good balance between stiffness and comfort. Volkl V-Star also offers some comfort in the form of polyester string.

  24. Hi John, I’ve seen, you has for the Babolat RDC Calibration 3 Rods. Could you tell me please the Diameters, Length, material and weight of the tree Rods?
    Thanks in advance

    • RacquetQuest

      Thank you for the question! I will send you the specifications tomorrow. I have “calibration” rods from various testing devices and have made a set for the RDC since calibration rods were difficult to get directly from Babolat. Thanks again!

      • RacquetQuest

        The one RDC Calibration Rod I have has the following specs:
        Diameter = 28mm
        Length = 36.5 cm
        Weight = 1756.6 gr
        Swing Weight = 315 kg/cm2
        Material = Not Sure

        I made several bars but use a 325:
        Diameter = 25.37mm
        Length = 38.5cm
        Weight = 1524.5 gr
        Swing Weight = 325 kg/cm2
        Material = CR Steel

  25. RacquetQuest

    I am looking forward to this new “Ask John” section! I believe this wil give all the viewers of this site an easy and quick way to ask any question!

    Please use it!


Leave a Reply to StevenCancel reply