Gear Talk: Wilson's John Lyons, Part 2
In part two of my interview with John Lyons, Wilson’s Global Product Director for racquets and strings, we continued our discussion of SpinEffect, an alternative (16 x 15) string pattern that the company claims can increase recreational players’ spin production. (For part one of the interview, click here.)
Justin diFeliciantonio: 16 crosses and 15 mains?
Jon Lyons: Yes, that’s what we’re calling SpinEffect. So as I said, most conventional racquets have symmetrical patterns: 16 mains by 18 crosses, or 18 mains by 20 crosses. There are more crosses than mains, which has to do with the ovalness of most racquet heads. And as I said earlier, fewer cross strings allow more movement in the stringbed. It sounds like a string technology, but it’s really a frame technology. Drilling the holes with one fewer cross changes how the strings exert pressure on the racquet. As a result, the construction for Steam 99S and 105S [pictured] had to be re-engineered, so that when the racquets come off the stringing machine they don’t deform. It’s not as simple as changing the grommet system.
JD: So the big question obviously is: How exactly does this alternative string pattern affect the snap-back effect?
JL: It affects it quite a bit. As I alluded to earlier, we spent a lot of time studying high-speed video. We would fire balls at stationary racquets with different patterns—one with a typical 16 by 18 pattern, another with a 16 by 15, both strung with Luxilon Alu Power—and would compare the snap-back. We measured not only the extent of the strings’ deflection—how far they moved—but also the speed at which they deflected and snapped back. (Since we knew that each frame [of high-speed video] was, let’s say, 1/1000ths of a second, and we could measure how far the strings deflected, we were able to calculate distance over time, or their speed.)
And what happens with the 16x15 pattern is that, compared to a 16x18, not only do the strings move a lot further, but they also snap back really violently. It makes sense. With less friction, the strings deflect further, and because they move further out of place, they snap back past their original position. Which increases the amount of rotation that the strings are able to impart on the ball.
JD: And a symmetrical, say 16x18 pattern doesn’t allow the strings to snap back past their original position?
JL: Not so much. If you watch the high-speed video, you’ll see that, maybe, the strings of a 16x18 snap back just barely past their original position.
JD: I imagine that, for somebody with a very quick swing, there’s going to be less durability with a 16 by 15. If the strings are moving more, they’re going to break faster, right?
JL: There is a little bit of a drop-off in terms durability. But it’s not as much as you would think. If you use the right monofilament string, it’s not that big a problem.
JD: This amplified snap-back effect: How much farther and faster are we talking about here?
JL: With the 16x15, the strings move 3.3 times as far and snap back with 69 percent more speed. Again, this is compared to a 16x18 pattern, with same racquets and monofilament strings. In specific terms, we found that with a 16x18, there was 6mm of [string] movement at a speed of between 1.4mm and 1.5mm/second. When we went to a 16x15, we went up to almost 20mm of movement at a speed of 2.5mm/second.
JD: Based on your research, was there a point at which, as you continued to reduce the number of cross strings, the data showed diminishing returns? Why not go with, say, a 16 by 14 pattern?
JL: There was, actually. Putting fewer and fewer cross strings does increase the amount that the mains are moving. But the big jump is between a regular pattern and just one less cross string, the 16/15. And as you go more and more open on the pattern, according to playtesters, it gets harder and harder to control the ball. So we think 16 by 15 is the right combination, even if you do get a little more string movement with even fewer crosses. With the 16/15, we think you benefit with the increase in spin without the negative of decreased control.
JD: Which do you think affects spin generation more? How far the strings deflect and snap back? Or the speed at which they do so? And how does the increase in string movement translate to RPMs?
JL: Good questions. Honestly, we’re not 100 percent sure which is more responsible for the spin, the distance or the speed. But about the effects on ball rotation: In a laboratory setting, when we’re firing balls off a stringbed—no player, stationary racquet, same ball being fired at the same angle—we’re measuring, on average, about a 10 percent bump up in spin.
JD: And in a game setting? What kind of RPMs have you measured with the Doppler radar device you referred to earlier, the TrackMan?
JL: We do have some real-world numbers, specifically with the Steam 99S racquet, which will come out in January 2013. What we did was a blind test with 24 players. They used completely blacked-out racquets, not even a logo on the buttcap. (And actually, we even told them not to look at the racquet.) So the playtesters didn’t know what racquet they were hitting with, nor did they know what we were trying to measure. We also used a ball machine to try to feed them a consistent ball to hit, in terms of spin and speed.
The experiment went like this. We said to each of the 24 players: “Take this first racquet, look over there where the ball machine is, and hit seven normal forehands.” So they would hit the forehands, reach back and get racquet number two, and then hit seven more forehands. So each of the 24 players hit seven with racquet number one, seven with racquet number two.
With this kind of sample size, you can arrive at statistically significant numbers. In this case, we compared the Steam 99S with the Babolat Pure Drive, which was our normal racquet. That is not meant to be a bash against Babolat’s racquet. It’s a great racquet. We picked it because it’s a very popular racquet that players feel gives them good spin. It also has an open string pattern.
JD: What were the results?
JL: On average, with the 24 players, of varied ability levels, their spin with the Steam 99S was 141 RPMs higher than the normal racquet. And normally, when you hit with spin, the ball goes slower, because more of the energy is going into making it rotate. But in this case, the ball went an average of 1.3 miles per hour faster, even with the additional 141 RPMs.
JD: I imagine that difference in spin would alter the arc and flight of the ball?
JL: It depends on the speed of your ball. But at the average speeds we’re measuring good players hitting at, every 100 RPMs in ball rotation causes it to drop about six or seven inches shorter in the court. So if you’re hitting with 200 extra RPMs, a ball that would clear the net by 11 inches lands one inch in, everything else being equal.