Effects of string spacing on racquet feel and behavior

[time_fly]

I am looking at two racquets side by side: a new P17 Pure Strike (16x19) and a new Pro Staff 97S (18x17). The P17 has 4 main strings up the throat with generally tighter spacing than the 97S in the neck area despite having 2 fewer mains and very open main spacing towards 3 and 9. The main spacing on the 97S is relatively consistent across all the mains. Conversely, the cross string spacing on the 97S at 3 and 9 is approximately the same as P17 despite having 2 fewer crosses. The PS97 is a little more open in the crosses towards the tip, and much more open towards the throat.

It makes me wonder how the string spacing pattern is created as part of a frame design. Is it trial and error, or is there a detailed model of string bed behavior that designers apply? Are there known pros and cons to even spacing versus uneven spacing, and what does it accomplish?

 

[Franklin_B]

I don't know if the designers model these things mathematically, but I would guess that the centre mains are tighter in some patterns because you get more control from dense patterns while getting less friction from the more widely spaced outer strings (dense middle, open edges).

 

[Zoolander]

You know, thats one of the most interesting questions i have seen asked here, and one that i have wondered myself. I would guess its a trial and error thing, there might be too many variables such as racquet head size/shape/design/flex/mains and cross string length to have a very detailed model of behaviour to follow. They would have the general attributes that certain patterns exhibit and then experiment with each prototype they make, i would think?

 

[esgee48]

You are comparing 'apples and oranges.' The question should be posted as 'If everything else was equal except for string spacing or drill pattern...' Assuming that was what you really meant, then your answer could be answered with the words SBS or DT. The 16x19 would theoretically have a lower SBS than the 18x17 assuming uniform string distribution. Crosses at the top and bottom have less of an effect on SBS than those in the middle. Contrast that with 18 mains vs 16 mains. If your string distribution is biased in one frame towards higher middle density, then the SBS will be higher for the frame with higher middle density. The inverse is true. But this applies only if they have the same string, same actual tension, same head size and shape, same length. Your hypothetical contrasts 2 very different frames which disallows any general conclusions from being made. Your body could probably tell you that one frame is softer than the other, but why would be hard to quantify. 2 cents.

 

[time_fly]

your answer could be answered with the words SBS or DT.

SBS? Sequencing By Synthesis? Shaken Baby Syndrome? Spanish Broadcasting System?

I wasn't implying I thought the differences between those frames are caused only by the strings. I was wondering, as you suggest, what the effects of different string spacing patterns is in the same frame. Clearly the designers chose those patterns for a reason, since the easy and obvious thing to do is space them all evenly after leaving some margin around the edges. Even in frames where the spacing isn't even, sometimes the unevenness is in the mains, sometimes it's in the crosses, and sometimes it's in both. So clearly the designers are adding some traits to the racquet with the string spacing.

 

[PBODY99]

SBS = string bed stiffness
As I recall, by a post spaghetti racket rule, the string pattern cannot be less dense in the middle of the string bed than on the edges.

 

[JonnyAbs]

SBS = string bed stiffness
As I recall, by a post spaghetti racket rule, the string pattern cannot be less dense in the middle of the string bed than on the edges.

That would probably give off center shots less power I would think. I assume that's the reason racquets are more dense in the middle, where you get more power, and more open on the edges.

 

[JonnyAbs]

I am looking at two racquets side by side: a new P17 Pure Strike (16x19) and a new Pro Staff 97S (18x17). The P17 has 4 main strings up the throat with generally tighter spacing than the 97S in the neck area despite having 2 fewer mains and very open main spacing towards 3 and 9. The main spacing on the 97S is relatively consistent across all the mains. Conversely, the cross string spacing on the 97S at 3 and 9 is approximately the same as P17 despite having 2 fewer crosses. The PS97 is a little more open in the crosses towards the tip, and much more open towards the throat.

It makes me wonder how the string spacing pattern is created as part of a frame design. Is it trial and error, or is there a detailed model of string bed behavior that designers apply? Are there known pros and cons to even spacing versus uneven spacing, and what does it accomplish?

In my experience, more open patterns give more power, high launch angle, and more spin (like the pure aero and PS 97), and more close patterns give more control (like pure strike and ezone dr 98). All of these racquets have 16x19 pattern, but the latter two have 8 holes in the throat instead of 6, so it is more dense in the middle.

 

[Tennisist]

One of the biggest problems is that the power of the rebound drops drastically away from the sweetspot and toward the edges. Take any racquet, and bounce the ball in the upper part of the hoop, and you'll know what I mean. I think the manufacturers are trying to alleviate this effect by making the spacing sparser outside the center. How well they succeeded is hard to tell. I do notice that some racquets with variable spacing have a bit more gradual transition, whereas in some other racquets any shot *not* inside the sweetspot is basically dead. I think this issue exists only on amateur level. Professionals hit the sweetspot >90% of the time. They are probably not going to complain or even notice that the power drops there. For them, it's all about consistency in the middle (with a fresh strings to that).

I reasonable solution will be to use 2 cross strings -- One for the upper hoop, and one for the lower. But no racquet provides any tie-off grommets for that ...

 

[zalive]

You know, thats one of the most interesting questions i have seen asked here, and one that i have wondered myself. I would guess its a trial and error thing, there might be too many variables such as racquet head size/shape/design/flex/mains and cross string length to have a very detailed model of behaviour to follow. They would have the general attributes that certain patterns exhibit and then experiment with each prototype they make, i would think?

I think mains and crosses spacing, placement and distribution interacts with design of the head (since it affects different mains/crosses length). And all that interacts with actual (specific) layup. On top of that it's type of strings in the string bed and their tension. There's also difference in grommets (classic or woofer design, width of holes or even port).

All in all...very complicated. Racquet design may look easy, and everyone might produce...something, but in practice, there's so much variables in here...

 

[alpenglo]

Wouldn't the effect of a less-dense string pattern in the periphery be an increase in power for off-center shots (i.e. less shock, less "dead" response)?

 

[Tennisist]

About dead zones / sweetspot: I have tried to tackle this via special stringing. See the picture below.

Here I use three separate strings, with three separate zones, each at different tension -- to alleviate the effects of sweet/dead zones that people have described above.
I must say -- it works. Compared to the uniformly strung racquet, this one offers a more uniform response all over the racquet face. You can feel it by simply bouncing the ball in various parts of the stringbed. It also helps that I use soft string outside the sweetspot. So there is definitely something in the idea that allowing the strings on the periphery to be sparser is helping to unify the response.

 

[Tennisist]

Here is another variation on the same pattern:

This inspiration came from a Pro Stock racquet (on the left).
Here, on the racquet on the right, I am missing strings on the left, right, and bottom -- on purpose.
The idea is to allow more trampoline effect in those areas. As you can see the pattern came out quite similar to a Pro Stock, which has a lot of "emptiness" on the left, right and bottom.