Originally Posted by 2ndServe
why not just skip holes while stringing your 18x20 racket.
If you skip every other cross you end up with 18x10. The racquet is designed to have nearly equal combined tension from the mains and the crosses. Therefore, when skipping crosses you must double the tension of the crosses to avoid badly distorting the frame. So you could string it up with mains at 50 and crosses at 100 pounds. But tennis strings can't handle 100 pound tension. Another option is to use kevlar mains, which are more than twice as stiff as copoly strings. Using kevlar, you could string the mains at 35 pounds and then use copoly at 70 pounds for the crosses. Because the kevlar is so inherently stiff, the mains will be a little stiffer than the crosses, even though they are pulled to only half the tension. This will not distort the frame, but those of us that have tried it have found that 10 is too few crosses. The poster Travlerajm has experimented with skipping crosses for two years and has found that with this number of crosses at these tensions the main strings move too much, which results in a very high and somewhat unpredictable launch angle. To solve this problem the tension has to be increased, but he has been unable to find a copoly that will last more than a short time when strung over 80 pounds. Here is a thread recapping his various experiments with skipping crosses: http://tt.tennis-warehouse.com/showthread.php?t=378484
I've tried 16x10 as well and found the same problems.
Wilson has solved this problem by a) designing the frame so that you can string it normally - both mains and crosses at the same tension - without distortion, and b) reducing the number of cross strings to 14. 14 cross strings is apparently enough to promote greater main string motion and snapback, but not too much. With 11 crosses you have to string very tight. Apparently with 14 crosses you can string at normal tensions and still get a controllable response.
An experiment that I'm working on now is stringing up an old Pro Kennex Micro 20x25 midplus as a 20x13. I will have to use kevlar mains with copoly crosses to avoid frame distortion, but I'm hoping that the total of 33 strings will allow for lower tensions than what we have observed with patterns like 16x9 and 18x10, and that the high number of mains will increase control. But this is just for fun. Maybe I'll find that 20x13 is awesome, but it's probably best to wait for the 16x15, which seems to work and doesn't require messing with kevlar or worrying about frame distortion.
For a better understanding of how string pattern, and especially reducing the number of crosses, impacts spin generation and rebound angle, please see these two papers by TW's own "Professor", Crawford Lindsey. These papers are certainly where Wilson got the idea for their new "technology". (They will not give him credit though as they are trying to patent this idea.)