Originally Posted by RD 7
Here are the top 12 softest strings tested in the TWU Lab (medium tension, fast swing speed). ZX MonoGut is the softest non-gut string tested.
Those numbers are somewhat deceiving. The ZX lost much more tension during the tension-loss part of the testing protocol than gut did. So when the stiffness testing was done the ZX was at a much lower tension than the guts were. Even still, if you correct for tension loss ZX is only about 30% stiffer than natural gut. Synguts are around twice as stiff as gut. Some of the polys are three times stiffer.