Category Archives: Natural Gut String
What Can String Failure Tell Us?
Well, in the simplest terms, failure tells us it is time to have the request strung! However, there may be subtleties in string failure that can help us in our quest for tennis racquet performance.
Such as?
Is the failure shear related or tensile strength related? Was friction the major contributor to the failure? Where did the failure occur (on the racquet, not the court)? Was the failure during play or in the bag?
Shear-related failure is when the string breaks very near the racquet frame. This failure is called a mis-hit or shank! It is like cutting the string with a pair of scissors!
Shear Failure
Friction Failure
Friction failure is caused by just that, friction! Friction is caused by the string moving on each other. That rubbing creates friction and notches the string where it will fail.
If the racquet failed during play and it is not shear-related, the tensile strength of the string was exceeded. If a string has a tensile strength of 120 pounds and the tension is 60 pounds leaving 60 pounds to be used to hit the ball. Some big hitters can generate at least that much force on a solid forehand!
This graph shows the tensile strength of the string to be about 115 pounds. Given the movement of this string-on-string, the frictional notching can contribute to relatively early failure based on the hitters force.
This graph shows the tensile strength of the string to be about 155 pounds but it has to travel (stretches) further to reach that force.
So, you can see, with this information we can make better decisions when asked to suggest a string, or strings, for a client!
Which Comes First!
We all have heard the question “which comes first the chicken or the egg”? However, my question is “Which comes first the game or the string”?
I believe they happen simultaneously. But first a quick story.
In 2005 I was attending a Head product introduction on the island of Mallorca, Spain, Yes, that one!
The product introduction was exciting but what I am going to tell you about now was even more meaningful.
The Director of one of the top US Tennis Training organizations, at that time, was there and we were discussing teaching techniques and what he said after being in this part of Europe was “we need to start teaching our players how to hit this way!” Well, “this way” was the way of low-powered strings that were popular in Europe but not so much in the US, yet.
So, it began! The players could not hit harder, like the Europeans, unless they used the same string material as the Europeans and that was very stiff and mostly PET polyester.
So, the idea was the “egg” and the string was the “chicken”, sort of! I guess the feeling was that “if Americans are going to compete we must use the same equipment”.
Now, I believe the professional game can go on about its way but otherwise, we need to consider changing the game by returning to a combination of comfort and playability.
Our history shows us that the “high performance” life span of many polyester strings is about 2-3 hours, or less, maybe about 10-12 games. We don’t believe this is quite long enough for most players. But, how do you quantify “performance”? It may be different things for different players.
There are many components to performance but what if it was associated with UTR data? Racquet Quest can track UTR numbers and make some determinations based on that data. If a UTR is stable or increasing it is a good bet that the performance of the player and equipment is OK. However, if the UTR is slipping it is a good indication that something is not working as it should…but what?
We have found that, in some cases, it is injury or discomfort, that is causing the slippage! Stop it! The following data is for a 12 month period and acquired from the UTR website. Even small positive changes are tough! But negative changes seem to have an enormous impact more quickly than positive changes!
For example:
| Player | Racquet | String | UTR1 | UTR2 | Delta |
|---|---|---|---|---|---|
| A | Head Speed | PEEK | 12.84 | 12.86 | + .02 |
| B | Babolat Pure Aero | Polyester | 10.91 | 9.56 | -1.35 |
| C | Head Radical MPA | PEEK | 4.50 | 5.61 | +1.11 |
| D | Wilson Pro Staff 97 | PEEK | 5.0 | 7.03 | +2.03 |
| E | Babolat Pure Aero | PEEK | 3.8 | 5.64 | +1.84 |
| F | Wilson Blade 98 | Polyester | 10.0 | 9.41 | -.59 |
| G | Head Radical Pro | Natural Gut | 3.7 | 5.15 | +1.45 |
Looking at the Differences
For the past fifteen (15) years or so, most string discussion centered on polyester. By now, you know our position on polyester, so we won’t go through that again right now. What we will go through right now is the difference(s) in a polyester string!
PET, polyethylene terephthalate, is the standard “material” in the better quality polyester string, so how can there be so many different versions of the same material?
Can you say “additives”? Luxilon has made it part of their brand to use acronyms for materials in each string’s description. ALU, for example, is aluminum, Timo is titanium/molybdenum, and I don’t know what 4G is.
So let’s take a look at the differences in a couple of polyester stings. Shown here are two (2) polyester strings, Luxilon ALU Power and Volkl V-Star. You can see the difference in stiffness between them, the V-Star being “softer,” but what you can’t see is the V-Star package does not say “co-polyester” but instead Co-Polymer!
Polyester? Co-Polyester? Co-Polymer?
We know “co” is two or more and “poly” is many, so how many of anything does any material have in it? We may never know and probably shouldn’t care as long as we have the presented data.
What can we see from this graph?
- ALU Power reaches 50 lbs quicker (stiffer)
- ALU Power exhibits good elasticity
- V-Star is more linear (consistency)
- V-Star has a greater tensile strength
- V-Star is softer (takes longer to reach 50 lbs)
How would a player know this by just looking a the package? I am not sure! Adding the word “soft” or “comfort” or “feel” may persuade a player to try the string, but what if a better decision could be made before spending the time and money?
Racquet Quest, LLC
