I have a 19 ft set of Topspin Cyber Blue. The racket I plan to string calls for 20 ft mains (16x19 pattern, 100 sq. inch head). If I use a starting clamp as a bridge for the string that comes up short, would 19 ft be sufficient to string the mains? Also, do you think 19 ft would be enough for a racket that calls for 21 ft mains if I use a starting clamp to act as a bridge? I really wanna put a set of Cyber Blue on my Dunlop AG 4D 300 Tour (18x20 pattern, 98 sq. in head)... but it seems that 19 feet would be insufficient, even if I extended the string.