Hi DKnotty -
With all things string related, intuition often fails. String is a highly mysterious creature! One would assume that with lower tension, string movement increases, and spin increases. Things are not so simple.
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Quote:
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Two things immediately stand out. The first is that the 16x10 60 lb. pattern creates the most spin for each string. And second, the 16x10 30lb. setup has by far the least amount of spin of any setup, except in the case of the Babolat RPM, where it still produces the least spin, but at twice the level as the other strings. The 16x19 setups produce a medium amount of spin, with the 60 and 30 lb. versions trading places back and forth for most spin output.
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These findings are somewhat surprising and confounding. If spin depends on lateral string movement, and thus low friction between strings, one might expect that the 16x10 30 lb. setup would produce the most spin, having fewer strings and lower tension. This was not the case.
Furthermore, if we thought low inter-string friction was most important to facilitating string movement and spin, then we might have figured that smooth polyesters would be best and that the setups would produce decreasing spin in this order: 16x10 30, 16x10 60, 16x19 30, 16x19 60. In some instances (TCS and Synthetic Gut) this is almost the case, but not in others.
TOO MUCH STRING MOVEMENT. So the first question we want to answer is why, contrary to some expectation, does the 16x10 30 lb. setup produce the least spin? The photos in Figure 4 reveal several cases of adverse effects in this setup. Two things immediately stand out. The first is that the 16x10 60 lb. pattern creates the most spin for each string. And second, the 16x10 30 lb. setup has by far the least amount of spin of any setup, except in the case of the Babolat RPM, where it still produces the least spin, but at twice the level as the other strings. The 16x19 setups produce a medium amount of spin, with the 60 and 30 lb. versions trading places back and forth for most spin output.
These energy loss effects are particularly apparent in the 16x10 30 lb. setups. The other patterns each, in their own way, minimize these effects and therefore produce more topspin. But they are not immune from such effects and each setup has its own dominating spin inefficiencies, involving too much friction or not enough tangential force — except, compared to the rest, the 16x10 60 lb. setup, which produces the most spin for all strings. "
-- Spin and String Stiffness, Crawford Lindsey
Link Here :
http://twu.tennis-warehouse.com/learning_center/spinandstiffness.php
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In the link provided above, I suggest review of the photos, and the commentary that demonstrates how string movement and deflection contribute to tangential energy loss. A simplified explanation is that if the mains slide too far, they lack sufficient energy to snap back in time to create any spin benefit. Too tight and they don't move hardly at all. So we are looking for the "Goldilocks" scenario where the string is neither too tight, or too slack. In addition, finding the right tension to maximize spin varies, as string pattern plays a key role.
-Jack
