Applying what we know about copoly - string savers

[charlieinneedham]

I have a question for Joshua Speckman.

What is the effect of string savers?

Supposedly they decrease friction, potentially allowing the strings to slide more.

But they also make the weave pattern more severe. That is, the string saver occupies space, so the main and cross strings have more distance to travel over one another, sort of like stringing with very thick string. So does this increase friction more than that lost from the "slipperiness" of the string savers?
But on the other hand is there then a potential for this weave pattern create more friction/bite for more spin?

I ask because I have been using a lot of string savers in the hitting bed between gut mains and alu power rough crosses. This definitely increases the longevity of the gut (much less notching), but it does feel different than playing without the string savers. I seem to have accommodated my swing pattern, and string tensions, to get plenty of power and spin, but wonder if I am leaving too much potential for spin behind.

[stumphges]

Hi Charlie,

I'm going to continue posting on the forum as stumphges, as I like to keep my internet footprint small.

Good question. First of all, nobody's studied string savers in the lab, so there is not objective or definitive data to guide us.

But we know that some stringsavers, Babolat Elastrocross and Elastocross II, for example, are made of PTFE resins (one of the trade names of PTFE is Teflon), so they are very slippery. Slippery, in terms of string on string friction, is good for spin.

But as you note, they also increase the angle of the weave, which Rod Cross says increases string on string friction.

My experience is that string savers do prolong string life, which can be nice with gut, but if you use them in a pattern (using 20-40 of them) they do seem to impede free string movement and impair the "snapback mechanism".

And I don't think it's just the angle of the weave that is the problem: the stringsavers have little grooves on them so they ride the strings like trains on tracks. But when the ball pushes a main string sideways, that main bowstrings - so its movement relative to the cross-strings is not linear. But the stringsaver forces it to move linearly. So this "train track" effect works to further impede main-string sliding and snapback.

I know of one guy who uses gut mains and copoly crosses and super-glues little bits of cut aluminum can onto the gut mains at the intersections. Aluminum can and copoly is a very slippery combination. And the aluminum is thinner than the stringsavers, so the angle of the weave is distorted minimally. This guy claims that his gut mains last for ages with these homeade stringsavers.

The Rule:

The racket shall be free of attached objects, protrusions and devices other than those utilised solely and specifically to limit or prevent wear and tear or vibration...

Interpret at your own risk.


One thing that didn't make it into the article is that the Japanese researcher, Kawazoe, says that slippery strings deliver less shock to the arm than strings that don't slide freely. I think this is one of the reasons why some people who hit with a lot of spin don't mind the inherent stiffness of copoly - they are getting it to slide and move, and some of the impact force gets deflected into that sideways movement. The "dwell time" - the amount of time the ball stays on the strings - is also prolonged when this happens, which is also known to reduce shock.

One of the characteristics of "dead" poly is that it starts to hurt the player's arm. This was always a bit paradoxical, because if the deadness is caused by loss of tension we'd expect it to get softer on the arm, not harder. But if "deadness" is at least partially caused by the strings getting scuffed up and sticking, rather than sliding, than it would make sense that the strings would start to feel stiffer and harder.

I mention this because I think that's one of the things that can happen with stringsavers if you use a lot of them. The increased weave angle stiffens the stringbed some, but if the strings are prevented from sliding freely by the stringsavers it would feel even stiffer and harder still.

[charlieinneedham]

It just occurred to me that I had not thanked you for your thorough and thoughtful reply.

Thank you.