Schimb racordajul, dar cand?

In Racordaje by Jazz0 Comments

“De ce trebuie sa schimb racordajul rachetei? In definitiv, daca nu s-a rupt, de ce trebuie sa-l schimb acum?”

Tennis Racket Broken by Tennis BallRaspunsul nu este atat de simplu avand in vedere carcateristicile rachetelor si racordajelor. Daca am cauta un raspuns cat mai simplu, acesta ar fi: trebuie sa schimbam racordajul pentru ca … puterea sta in racordaj. Daca nu este clar, incercati urmatorul exercitiu: luati o minge de tenis, lasati-o sa cada, din mana, pe o suprafata plana (terenul de tenis!) si vedeti cat de inalt va sari. Apoi, procedati in acelasi fel dar in loc de teren folosti racheta (incercati sa o sustineti in asa fel incat sa fie paralela cu terenul). Vedeti diferenta?

Totusi, veti spune: “Bine, bine, dar daca racordajul nu s-a rupt, de ce trebuie sa-mi cheltui banii pentru unul nou? Mai bine fac altceva cu banii; ies la bere cu baietii (de la FanSport  ) sau gasesc eu ceva.”. In principiu si eu as face la fel dar tot vreau sa ajung sa mai joc o partida de tenis, candva.

Am scris intr-un articol anterior, ca racordajele au anumite carcateristici ce nu sunt mentionate de niciun producator de racordaje desi sunt foarte importante pentru un racordaj:

ELONGATIA (ELONGATION) – orice racordaj se “intinde” atat in momentul tensionarii (racordarii) cat si in momentul imapctului cu mingea, dar ceea ce este foarte important este capacitatea acestuia de a reveni la starea initiala, iar aceasta carcateristica se numeste:

ELASTICITATE – rata de revenire la starea initiala este ceea ce desosebeste cu adevarat un racordaj de altul. Atunci cand racordajul este nou, rata de revenire este apropiata de 100% ceea ce rezulta intr-o mai buna accelerare a mingiei si o mai buna recuperare dupa o lovitura spin („Corzile nu s-au miscat deloc!). In timp, dupa cateva ore de joc, rata de revenire va scadea ceea ce va conduce la o pierdere a controlului si a puterii si veti cauta tot felul de varinate pentru a tine mingea in teren, acolo unde doriti sa ajunga.

Iata mai jos cateva diagrame  (obtinute prin amabilitatea firmei Stringway)

poza1

 

Poza2

Daca analizati diagramele de mai sus, veti ajunge sa intelegeti de ce racordajele multifilament (sau matul natural) sunt mai “bune” (dar si mai costisitoare) decat cele monofilament. Sau, veti intelege de ce in articolele mele sugerz ideea folosirii racordajelor monofilament dar la tensiuni mai joase decat cele cu care v-ati obisnuit. Explicatia: tensiunea mai mica provoaca o Elongatie mai redusa pastrand si elasticitatea intrinseca a materialului.

In concluzie, trebuie sa schimbati racordajul pentru ca elasticitaea acestuia nu va dura o vesnicie. In plus, nu vreti sa va treziti cu racordajul rupt in timpul meciului! Corect?

Si cum putin umor nu strica, citez mai jos un articol scris de un anonim domn Crawford Lindsay (este in engleza dar daca aveti probleme in a-l citi va sugerez sa folositi Google  ) :

„When to restring.

In 1992, we got a dog. Then we got another. Then we got three cats. But I digress, already.

The dogs were the beginning of what would be an 11-year experiment in tennis science. Everyday for all those many years, I hit tennis balls in the backyard with a racquet, and the dogs would fetch. They ran a circle. As Emma was bringing a ball back, I would hit another for Molly, and vice versa. In the early years, that could go on for an hour. Later it was a half-hour, and most recently only 15-20 minutes, due to bad dad syndrome, rather than any waning enthusiasm for the experiment on the dogs’ behalf. In any case, hundreds of experimental impacts were recorded each and every day.

The experiment, of course, was to test the durability of tennis strings under extreme environmental conditions to determine a recommended restring frequency. The racquet remained outdoors for five years in Colorado and six years in Southern California. It endured torrential rains and floods, blizzards, extreme cold, and blistering heat. The balls (thousands) remained outdoors too. They became deliciously caked with mud and dog spit, as did the strings. And buried within those caked layers was a geologic record of all the dirt, grime, pollens, pollution, vegetation, minerals, gradoo, and doo doo of those years. Man could I get some spin!

Anyway, a couple of weeks ago, a string broke. Finally, my research was over. I could rest at last, knowing that I now know the answer to the cosmic question of how often you should string your racquet — EVERY 11 YEARS! Of course that is under extreme circumstances. You may get twice that under normal playing conditions. But to be on the safe side, and to generate more restringing revenues, I’d simply recommend every 11 years.”

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