Category Archives: Elongation
Questron Cycle Update
Every string that enters the World Headquarters of Racquet Quest goes through the Questron cycle. We have posted images of the product of the cycle, but not the entire process that the Questron goes through to create these posts.
The following video is the entire process from start to post. We look forward to your comments!
If you have a string, or strings, that you would like to know more about, please let us know. We may have already put them through the Questron Cycle.
I mistakenly said “Z” axis when I meant “X” axis, if you caught it.
NG Strings – Part Two: Natural Gut Knot Strength
Any string that goes into a tennis racquet is, at some point, going to be tied off using a knot. Creating a string knot is normally not an issue, however, some strings are more sensitive to this process than others.
This plot will show the relative difference between gauges, and other properties. We can see that NG17 gauge did not quite make it to the stress/strain ceiling of 50 pounds. That is why there is only a single line while the other two (2) go through the cycle before the knot fails.
This is a tough test for natural gut due to the coefficient of friction (COF) being pretty high meaning the overlapping strings are like sawing at each other as the knot is being pulled tight. The knot strengths in the 60 pound range are suitable and will not, typically, be a problem. Be very careful with values less than that, however.
Natural Gut Knot Strength
And, while we are talking about knots, we need to consider the best practices for tying off other strings on natural gut. The best practice is don’t! Find a grommet that can be suitable for tying off another material type on itself…not the natural gut. Obviously if the entire string bed is natural gut it is a good idea to find a suitable tie off on a cross string.
There are other considerations when typing off on natural gut and we will have look at these in a future post.
The power potential of the NG Strings has beed added to the String Power Potential page and can be seen here.
Just type in NG Strings in the search field if you don’t feel like scrolling!
Accuracy Index…What is it?
For several years, Racquet Quest has been testing racquets we have strung for an “Accuracy Index.” Click here to see an example, and then we will discuss it.
For several years, Racquet Quest has been quantifying racquet string bed behavior using our internally developed Accuracy Index. This post was drafted in 2019 but not posted util now. Why now? Players, and us, are even more frustrated with the lack of quality racquet preparations than we were in 2019! We are seeing more and more really bad stuff happening so this post may be a way to address the bad stuff and do better!
The first graph presents the relative stiffness of the main and cross string arrays, as well as the average composite stiffness. On the following page, the Accuracy Index data grid provides a segmented view of the string bed, with each color-coded cell corresponding to a specific impact zone.
This grid allows us to analyze local stiffness variations, where, for example, light blue cells typically correlate with premature failure points in topspin-oriented play. The example shown references a standard 16×19 string pattern, but the analytical framework is applicable to any string configuration.
Why does the Accuracy Index matter?
In performance terms, control is effectively a function of predictability. That is, the extent to which the string bed returns the ball along an expected trajectory with minimal variability. The Accuracy Index quantifies this by comparing actual deflection characteristics across the bed to idealized stringbed behavior. Higher accuracy values imply lower angular deviation and more consistent ball exit vectors.
We also report an Efficiency Index, which assesses how effectively the stringing process preserved the frame’s intended geometric and mechanical properties. A lower efficiency score (e.g., 71) indicates that the racquet had to internally redistribute loads—compensating for distortions incurred during stringing. This can result in non-uniform string tensions and unintended stiffness profiles across the bed, reducing both playability and predictability.
At Racquet Quest, our stringing systems utilize frame stabilization techniques that eliminate distortion during tensioning. As a result, our stringbeds exhibit minimal deviation from target parameters, allowing both Accuracy and Efficiency indices to remain at consistently elevated levels.
Implications for Racquet Technicians
Regardless of the equipment used, technicians can leverage the Accuracy Index as a diagnostic tool to identify inconsistencies introduced during stringing. Adjustments to clamping sequences, pull timing, frame support, or pre-stretch protocols can measurably improve stringbed linearity and reduce compensatory distortion.
In essence, a higher Accuracy Index isn’t just a number—it’s an indicator of a racquet’s ability to perform as engineered, shot after shot.
Comfort is the new Soft!
Over the years descriptive terms for tennis strings have endured many mythical, and even wrong, definitions.
One of the terms we continue to hear is “Synthetic Gut”. First of all, in terms of tennis string if the material is not from a once living animal it is “synthetic!” The term “synthetic gut” was responsible for relegating “nylon™” to the very lowest of low end tennis string, however, even today Nylon™ makes up a substantial percent of the tennis string material!
Now comes “Comfort” trying to relegate “Soft” to the scrap heap!
What difference does it make? A lot. Seasoned players know what works for them and they don’t care what anyone calls it. On the other hand those just beginning or wanting to improve their game do care.
With our in-house testing device, Questron, we test every string that goes into a racquet, and every string that comes into the World Headquarters . The graphs have been posted on this site a few times but just in case you missed them here is a graph:
This graph represents two (2) polyester strings and one (1) natural string because it was handy.
In the simplest terms the quicker (shorter deflection) the string reaches 50 pounds the “stiffer” or less “soft” it is. Neither of the polyester stings are “soft” compared to the natural string, however, one polyester string is “softer” than the other polyester string but not by much.
We have tested many strings that are now available in a “soft” version and the “standard” (not soft) version.
Whatever string version you choose use it because it works for you whether is it marketed as Comfort or Soft!
Racquet Quest, LLC
