The thing I don't particularly get is how this pre-streching works. I'm agnostic on WC, but they are really popular, which either means folks are falling a little hard for them, or probably that they are better. The weird thing about all this is that all this is going on while we are dealing with the lowest stretch string materials that we have ever seen. Generally well engineered fibers have a low stretch at first, then when loads get high, they stretch out, then you reach the proportional limit, and they stop stretching in the elastic way recoverable way, then they break. I guess one can engineer these things any way one wants, both through the fibers, and also how they are layed up into strands, or ropes and loops. In other fields, however, where the materials are being worked at much closser to their limits, the materials are regarded as being essentialy equivelent to wire rope in stretchiness, essentialy zero. When Kevlar strings first became available we were looking to put stretch back in. But my basic point, that I would like to have corrected by someone who really knows is how are these strings that are only being streched when made at something like maybe a 10% load, how are they stretching at all.

That is why I disagree on the idea the stretch is in the fiber (though it could be, but if you have ever tied with the super fly tying threads you can't help but wonder). If you ask what is different about our use, the most obvious parts are these strings are being layed up differently than a lot of rope, some of which have minmal twist; Where they are covered, the covering is applied under great tension; The main string is used arround a pulley, but might be being layed up in a line; At least the tradition of strings is that they are made by hand. These are four areas that beg for the fibers to re-arrange themselves after the string is made, rather than to stretch as a result of some pre-existing stretch in the fibers.

Anyway, why do we have strings with twist? Originaly, going back 10-15 years (not really original) there was a convergence between the fact that the flemish strings (cool two colors) where gaining popularity due to the emergence of the Traditional market. For a short period in time the other makers needed a little more stretch than the new materials were giving, until they got the new bow structures right. There is the issue of the ability to double twist strings to get peep adjustibility into them. As far as I know FITA shooters are mostly using strings with minimal twist, though how much is a critical recurve adjustment issue. Twist usualy gives a quieter string, but there are a load of ways of doing that. If the only real reason is because the two colors look cool, that isn't much of a reason. Less twist is one way to get rid of stretch.