Category Archives: Technology
I have been working on these new models for a few days and will post more data as it is available but right now here a few points about this fascinating racquet concept.
The two (2) models are Speed Adaptive and Instinct Adaptive. The racquets are both new versions of the current models with slightly newer graphics, that are, in my opinion very cool! The Instinct has new graphics which will appeal to more players.
First, the Adaptive Tuning can create thirty-two (32) possible combinations, including increasing the overall length of the racquet.
The racquets are shipped in the lightest (285 gram), 16×19, 27.0-inch length format, and swing weight 287.
The Adaptive Tuning Kit is required and costs $29.00. In the “kit” you will find a “heavy” butt cap insert, three (3) sets of grommet inserts to add weight and change string pattern, and three (3) sleeves that go onto the shaft to create length.
The length modification can be made quickly by the player, if necessary, however, the other modifications require the racquet to be unstrung.
These modifications should be left to your racquet technician.
Below is a spreadsheet representing the various combinations as they are applied. This does not include all the options because the 16×16 grommet set did not participate in this session.
This was done at Racquet Quest, LLC and represents actual data, not calculated characteristics.
What is “soft”?
In 1994 I did a presentation for the USRSA in Atlanta. What was the topic?
It is now 2016 and we are still trying to understand string! Especially “soft” polyester based string.
In 1994 PolyStar was the only polyester based string I was familiar with. Since then there are dozens of offerings from anyone that can afford to purchase from manufacturers and market the string. If you have a desire to do it I applaud you!
In 1989 I started testing string and calculating “power potential”. Why “power potential”? Because “modulus”, “elongation” and “elasticity” didn’t get to the bottom line of string performance quickly enough! The steps to arrive at power potential are many.
For the testing, several calculations take place including “stretching” the string as in a ball impact. The difference between the first calculation and the “stretched” calculation is the power potential!
I have calculated hundreds of power potentials but have not until now quantified “soft”.
I think now is the time!
Dr. Rich Zarda has done a tremendous amount of work on this issue so we can now distill this work into the following explanation.
So, what is a “soft” tennis string?
Strings in a tennis racquet carry the ball impact load in two ways:
1) Via the pre-load string tension placed in the strings caused by a stringing machine (and the racquet frame “holding” those tensions in place) and
2) Via additional tensions that develop in the same string caused by the elongation of the strings as they deflect with ball impact.
Both of these conditions occur simultaneously and contribute to the string bed stiffness (SBS, units of lbs./in). Racquet technicians measure SBS by applying a load to the center of a supported string bed and measuring the resulting deflection. Dividing the load by the deflection provides the SBS (lbs./in). The lower the SBS, the more power you have (power here is the ability of the ball to easily rebound from the string bed), but the less control (presumably); the higher the SBS, the less power you have but the more control you have (presumably).
One more point about SBS: the lower the SBS, the less the load your body will feel for a given swing. But for an SBS too low (less than 50-80 lbs./in), balls will be flying off your racquet going over the fence; and for an SBS too high (greater than 200-240 lbs./in), the racquet will hit like a board with significantly less ball rebound. So the most common SBSs are between 100-200 lbs./in: a balance between control and power.
As already expressed, SBS is a function of the pulled string tension and the string elongation. Here is what is interesting: For large string elongations (for example, greater than 15%) and reasonably pulled string tensions (greater than 30-40 lbs.), SBS only depends on the pulled string tension and it does not depend on string elongation. Additionally, for this condition, SBS, for these high elongation strings, does not change as a ball is hit with more impact.
But for a string bed with low elongation strings (less than 5%) under low pulled tensions (less than 20 lbs., or tensions that have been reduced due to racquet deformation and/or string tension relaxing with time), the SBS additionally depends on the string elongation and will significantly increase, in a nonlinear ever-increasing way, for harder ball impacts.
In order to achieve a repetitive feel for a player when hitting with a racquet, it is best to have a SBS that is independent of an increasing ball impact force. This will lead to a more consistent playability of the racquet, which includes a more repetitive feel. This desired “feel” implies using high elongation strings (greater than 10%). If low elongation strings are used (less than 4%), the SBS will significantly increase as the ball impact force increases, resulting in a racquet feeling “boardy” for higher impact loads. And low elongation strings will cause un-proportionally increasing load into the body.
As you can see by the graph, elongation contributes to SBS in a big way. The red line indicates a stiff string, about 4%, and the blue line indicates a “soft” string, about 15% elongation. You can see the loads increase dramatically as the impact increases. So the harder the hit the higher the loads on the body.
So to the question asked at the start “What is a soft tennis string?” In the context of the SBS discussed above, I would suggest that a soft tennis string is one whose elongation is 10-15%, and a stiff tennis string is 4-6%. And any string under 4% should be categorized as ultra-stiff.
String elongation (soft, stiff, ultra-stiff), stringing machine strung tension, and string pattern(s) all contribute to SBS and SBS is an important measure of how a racquet plays and should be adjusted for an individual player, stiff and ultra-stiff strings can lead to less-repeatable racquet performance and player injury.
Soft = 10 -15% Elongation Power Potential Range = 10.0 – 16.0
Stiff = 4 – 6% Elongation Power Potential Range = 4.0 – 7.0
Ultra Stiff = Less than 4% Power Potential Range = .65 – 3.96
Racquet Quest, LLC, with the help of Dr. Rich Zarda and myself, invite you to meet us at the World Headquarter’s of Racquet Quest, LLC on Thursday, October 20th at 7:00 PM for an open discussion on tennis racquets, and, strings technologies. We expect to finish no later than 9:00 PM.
This first discussion is open to the first twenty (20) that respond, and, are attending. If this discussion is worthwhile, we plan on supporting larger groups in the future.
Racquet Quest, LLC is located at 3490 US 17-92, Casselberry, FL 32707, directly across from the Home Depot. You can find directions at www.racquetquest.com.
This is a “discussion” not a “sales” meeting, so your questions are solicited. If you want to send your question to me, email@example.com before the meeting date, please do so.
We will answer any prior questions at the discussion so everyone in attendance will hear the same answer.
Light refreshments will be served.
We look forward to seeing you here! Please RSVP with a phone number and/or email address. Time and space is limited.
Thank you for your interest…
Building a “custom” racquet is exciting not only because of the work involved but from the “joy” of the finished product!
When I receive racquets similar to the state shown the first thing that happens is numbering and characterization so it can be tracked throughout the process.
The first piece of equipment I use is the Ereca Balance System. Here is why. The two (2) scale system is fast and extremely accurate. This first “pass” tells me how much work is required to get the racquets to the customers specification.
These racquets had an average deviation of 1.69 grams! Other specs were also very close. Knowing this when I start the process means I can pick almost any of the racquets with confidence that I can achieve the desired “finished” specifications.
As you know I insist on swing weight as a major racquet property but this system gets me off to a great start and saves considerable time.
Each client has a specific specification they want in terms of length, swing weight, overall weight, grip size, grip material and where any modifying material, if required, will be added.
Adding string is a big factor because of the different weights of various string. Stringing is, typically, the final step in customization if any material is under the bumper guard
Custom racquets are not only fun to build they are fun to play with!
I am very happy to have Eric Ferrazzi of Ereca Tennis visiting Racquet Quest!
Eric designs diagnostic equipment for technical tennis shops. Racquet Quest has been using some of the Ereca designs for several months with great success and acquiring better data.
It is important for us to recognize what we can do with proper equipment, and, take advantage of the technical designs of the Ereca Team.
Ereca has many other designs that are in the “evaluation process” and Racquet Quest is happy to be involved!
Now if Eric could just teach me how to cook French food…
Racquet Quest is in the racquet technology business! What does that even mean?
It means we devote a great deal of our time to understanding racquets and what makes them ”tick”. Of course, it is fun and meaningful but sometimes not well understood.
Hardly a week goes by that I don’t have a request for “Pro Stock” racquets of some sort. But what does that mean?
To help sort out this question I reached out to one of the people in this industry that knows the answer! Jerry, I will call him, works for a major racquet manufacturer and is responsible for racquets for professional players. I asked him to comment on the following narrative. The responses are in red.
Pro Stock Racquets. What does that even mean?
“Rackets which have been customized to players need.”
“Many people believe that pro players are using different construction, which is actually not true; a reason to think so is that these people have no idea about racket production.”
For years, it has been the position of manufacturers that the “retail” version of racquets did not work for the top world ranked player(s). So what to do?
“Players need different weight/balance/swing weight than regular players due to their fitness and technique.”
Many “pro” players prefer the model they started their career with but those racquets have long been replaced by newer, and mostly, better technology regarding materials. Of course, it is “possible” to use the older mold, (the mold is not the graphite tube), to re-create the preferred geometry and feel. I doubt that the materials I used in our racquets many years ago are still available.
“If players are used to their old/first racket as their extension of the arm/hand in many cases they don´t want to switch unless they feel they have to!”
Probably the most important consideration is the third paragraph. “Players need different weight/balance/swing weight than regular players due to their fitness and technique.” Why would I even think I can play with the “same” racquet as Roger, Novak, Andy, Rafa, and the rest of the top players! It is simply not possible.
Yesterday I finished an “evaluation” racquet for a pro player with a swing weight of 400 kg/cm2 with an “even” balance. Is this a “pro stock” racquet, or just a racquet that has been radically customized?
I can, however, make my racquet the best it can be for ME! So, let’s go back to the top of the page,“Rackets which have been customized to players need.”
It doesn’t matter to me at what level you play but as racquet “technoligsts” we can help you be a better player.
Well, I made it to see 2016 arrive! I am not sure why I stayed up but it does commit me to pay attention to what may happen in the coming year.
I think the big story for 2016 is going to be more string related than racquet related. Why? Because manufacturers can “turn around” a string model much quicker than a racquet model, and, there are significant areas for improvement in selecting the correct string material for each player physicality and style.
String characteristics, materials, tensions, and applications are confusing to many and rightly so. This year I want to continue the “educational” effort and invite anyone with something to contribute to speak up.
My motto for 2016 is “Speak Up…Then String Up”
As a stringer you may, on occasion, clamp the string on the outside of the racquet frame.
This clamping can cause stress on the string right where it needs to bend or near the tie off area. This is not good!
The Offset Tube protects not only the racquet, but, more importantly, the string, by clamping about 2 inches away from the bending, or tie off, area of the string. The design and specific material properties of the protection pad assures proper protection without “tension loosing” softness.
This “quick and easy” to use device is a must for the serious racquet technician, and, if you are player be sure your “stringer” has an Offset Tube to protect your string!
The Offset Tube will be shipping starting the first week of November.
Each Offset Tube is $9.95 plus $2.00 shipping for up to two (2) in the US.
Your payment will be processed via our PayPal account but you do not have to have a PayPal account in order to pay. You can use any credit card.
String Bed Linearity is how the stiffness of the entire string bed reacts to increased loads. A load would be how hard the racquet hits the ball, or impact.
I collect this data on virtually all racquets. My methodology involves applying a measured load to the string bed and recording the force required to deflect the string bed that amount. The load is increased five (5) times and the corresponding force is recorded.
The data shown here is for a racquet that was strung at a low reference tension. Increasing reference tension will, of course, increase each load number, however, the “percent linear” should be proportionally the same but the non-linearity may occur at a lower load.
If, for example the first load requires a force of 13, like the chart shows, then a linear string bed would increase by 13 for each deflection with a final number of 65.
Then, the first deflection for both “perfect linearity” and “Measured Linearity” will be the same, in this case 13.
To better understand why this is important it is necessary to know that polyester based string, such as this one, exhibit very low elongation, somewhere around 5% at 60 pounds. This requires more force by the player to return energy to the ball and take advantage of the string movement that is thought to “snap” back and create ball spin. The potential issue is that this is the force area that begins to go non-linear and stiffer!
I prefer to use polyester based sting only for players that have developed strokes, and, developed strength in the wrist and shoulder. There are many players that are not able to realize any advantage of polyester, and , therefore, should be introduced to alternative strings.
In summary, then, it makes sense to find a string that exhibits “perfect linearity” or slightly below perfect. This means the string bed is getting “softer” as the ball is hit harder. As you would expect string bed linearity depends not only on the string but the string pattern, tension set, the machine, and the person installing the string.
As you know Head has made incredible strides in terms of racquet technologies and important players using them!
The racquets I received recently are the new Head Graphene XT Extreme MPA. Richard Gasquet, a talented and great player to watch, has been using the “Extreme” model for several years and has been making it into the late rounds at more tournaments!
The bright yellow finish with bright red and black certainly makes a statement! The black grip is a slight departure from the more usual white synthetic grip used on many racquets.
The new model incorporates the ASP technology that allows the racquet to be strung either in a 16 x 19 pattern or a 16 x 16 pattern! One racquet two string pattern options! Great idea, I think!
This model weighs in at 319 grams (11.25 ounces) with a swing weight of 322 (11.36 ounces) with a RDC flex of 60 (compare to 71 for the Babolat Pure Drive).
I installed a new Head string that is not polyester! The new string is Velocity MLT, a multifilament polyamide (nylon) with about 10.2% elongation. The string bed stiffness is a comfortable RDC 61 and DT of 38.
If you are considering a new racquet consider this one for sure!