View Single Post
Old 10-20-2012, 08:09 PM   #29
Hall Of Fame
ChicagoJack's Avatar
Join Date: Aug 2005
Posts: 2,187

Originally Posted by corners View Post
Just wanted to note that Topspin Cyberflash 17L, which comes in as the least stiff copoly in Chicago Jack's updated list is quite a soft poly, but the stiffness number being so low is largely a result of how poor it is at holding tension. (The stiffness is measured after tension loss.)

Here is Cyberflash 17L vs. Gosen Sidewinder (Stiffness) ... (CoF) ... (Total Tension Loss):

Cyberflash 17L (166.3) ... (.098 ) ... (34.8 )

Sidewinder 17 (180.6) ... (.090) ... (24.5)

Both strings were strung at 60 pounds but after striking the strings with a hammer 20 times in a manner designed to simulate 20 120 mph serves, the Cyberflash 17L ended up at 27.52 pounds and the Sidewinder 17 ended up at 37.84 pounds. These are the tensions at which they were tested for stiffness. The Cyberflash had ten pounds less tension on it at that point - no wonder it tested so incredibly soft.

If we use the TWU String Performance Database and sort by "Actual Tension", the actual tension it is tested at following the tension-loss simulation, we can do a more direct comparison of the stiffness of these strings:

Cyberflash 17L (strung at 60 pounds, but tested at 27.2): (166.3)

Sidewinder 17 (strung at 50 pounds, but tested at 27.85): (159.4)

(Also, I think Nanosilver is a multi)

Corners -

Cool. Thanks for the heads up. I figured that tension loss was a factor, I just had no idea the disparity, it's a huuge deal it would seem. I'm flowing the actual tension / pre test digits into the list now. I will keep the reference tension (62 lbs) and swing speed (fast) so that the parameters of the two indexes remain consistent. When I get those three sets of digits all stacked up, somebody a whole lot better at math than I am, ought to create some sort of formula to assimilate the implied meanings of the three factors (hint hint)

(9x) Donnay Pro One 16x19 | RPNY Leather | 12.6oz, 12 Points HL, ~340sw | Gut/Zx | Currently Tinkering With : Blade98s, Steam105s, Tec315Ltd.

Last edited by ChicagoJack; 10-20-2012 at 09:26 PM.
ChicagoJack is offline   Reply With Quote