Bentley Fortissimo

The Bentley Fortissimo tennis racquet of 1972 was the first oversize tennis racquet to be produced and demonstrated publicly. Prior to its introduction, all tennis racquets were much smaller in terms of the stringbed size, measured in square inches. Today, that size, known as standard, is not used by any professional player for professional match play.

The Fortissimo was shown in 1972 at the "Spoga", a sporting goods show in Germany. Its designer is Kurt Klemmer, who made the racquet with an epoxy fiberglass process. The Fortissimo was not produced on a commercial scale. Racquet engineer Siegfried Kuebler stated that it did not create a favorable impression with tennis players but was positively received by racquet designers.

The Fortissimo emerged two years prior to the filing of the influential and lucrative patent for racquets sized 95-135 square inches by Prince Sporting Goods (now Prince Sports and commonly called Prince). This resulted in the disqualification of the patent by the German patent authority. The Prince patent was upheld elsewhere and the company became the only highly successful seller of oversize racquets in their early history. The first was the very flexible aluminum Prince Classic of 1976. Tad Weed introduced the first super-oversize in 1975, to start a line that continues to be sold today.

Although metal racquets became popular in the 1970s, beginning with the invention of the 1963 Lacoste steel racquet that became the extremely successful Wilson T2000, synthetic materials, beginning with fiberglass and culminating in graphite, would eventually completely displace them from all but the low-budget recreational line sold in generalist stores such as WalMart.

The Yamaha Corporation saw success in the marketplace in the 1970s and early 1980s with fiberglass racquets made with the small "standard" head size such as the YFG 10. Several other companies introduced racquets made just with fiberglass as well, such as Caldon and Head. As with the Yamaha, these were made with the standard head size. The Fortissimo, however, was made with the new oversize head size, using the improved resistance to warpage (when compared with wood) and lighter weight (when compared with metal) of fiberglass. Fiberglass never achieved market dominance, though, as wood racquets with graphite layering and metal racquets, including oversize models, continued to find popularity. Graphite, which offered better stiffness and resistance to cracking than fiberglass, eventually displaced all other materials as the primary constituent material of a tennis racquet.

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