Isometric Swing Power 900
Model ISO-SP900 · Gong Zhichao
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Isometric Swing Power 900: one racquet in four types, and Gong Zhichao’s 1998 Japan Open
Four racquets under one name
Yonex Japan put the Isometric Swing Power 900 on sale on January 30, 1998, at ¥20,000 before tax, and sold it as a “new proposal.” Instead of one specification, the model came in four types that differed in weight, flex and balance, so a player could choose by style: SX (extra) and SS (stiff), at 87 g, for attacking singles and doubles players respectively, and SR (regular) and SA (average), at 81 g, for defensive singles and doubles players. Yonex called the idea the Swing Power Theory: “within one model, weight, flex and balance clearly divided into four,” as its ad put it. Its 2017 anniversary site names the 900 among thirteen landmark isometric frames, between the 1996 Super Isometric 10 and the 1999 Ti10.
The Swing Power numbers
Yonex’s launch ad gave each type a balance point and a “swing index,” the product of weight, balance and the distance from the grip to the impact point, where a lower figure meant an easier swing: SX 305 mm and 145, SS 300 mm and 143, SR 310 mm and 138, SA 305 mm and 136. Its export catalog rated the four as Extra Stiff, Stiff, Regular and Flexible, labeled the weights 3U and 4U, matched each to a player (smash, drive, high clear, receive) and added a calculated power level for each. The frame was high-modulus carbon with what Yonex called a tough beam, the shaft ultra-high-modulus carbon. Yonex Japan listed the color as gold; in its photos the frame is navy and the shaft and handle cone gold. It recommended 16–18 lb mains and 18–20 lb crosses; the export catalog suggested 2 lb less for the SR and SA. All four had one grip shape, to be built up with tape.
Gong Zhichao’s SR
Yonex’s 1999 export catalog tells the model’s one documented player story, under the heading “Swing Power enhances the ability of top pros like Gong Zhichao.” It says China’s Gong switched to the Swing Power 900 during the 1998 Yonex Open Japan and won the women’s singles, and quotes her: “I tried all four Swing Power specifications before the tournament and settled on the SR. I got a lot more power and I won my first big tournament.” The final was on January 18, 1998, in Tokyo, where the second seed beat the top seed and world champion Ye Zhaoying 11–1, 11–4, twelve days before the racquet went on sale in Japan. The contemporary match report names no racquet, so the link rests on Yonex’s catalog. Gong won the Yonex Open Japan again in April 2000 and Olympic gold at Sydney that year; Yonex Japan’s reports of both name no racquet, and Yonex’s anniversary entry for the 900 names no player.
The 500 and the Ti Swing Power
The four-type idea outlived the 900. The cheaper Isometric Swing Power 500 (item ISOS500, ¥16,000, Yonex color silver) used the same SX, SS, SR and SA types, tuned for intermediate players’ swing speeds; Yonex’s 1999 export catalog shows it as new beside the 900, listing a graphite frame and shaft in place of the 900’s high-modulus materials (Yonex Japan’s own page calls the 500’s frame high-modulus carbon and its shaft all-carbon) and a silver shaft in place of gold; it has its own page. In 2000 Yonex Japan’s lineup had the Isometric Ti Swing Power (item ISO-TIS) in the 900’s place: black at launch and orange from late 2001, ¥21,000 before tax, with titanium mesh in the frame and the same four types, each listed as 10 mm long, on sale until production ended in 2005; it has its own page. Yonex’s 2000 export catalog still credited the Swing Power Theory, introduced in 1998, with winning wide recognition, on a page that showed the Ti Swing Power as new beside the 500.
A run of under two years
The 900 had a short life. Yonex Japan’s badminton homepage featured it from its earliest archived version, in late 1998, until October 1999; from mid-October 1999 the page promoted only the Ti10 among racquets, and Yonex Japan’s 2000 racquet page and its 2002 old-model index do not name the 900. Those pages show new or selected models, so no production end is documented, and 1999 is the last year Yonex lists it. Because it was sold as four types, any frame is one of four variants, and the type tab and the weight say which. No verified sales are recorded yet.
Copies and mismatches
No counterfeit of the Swing Power 900 is documented. Since one name covers four racquets, the practical risk is a frame described as the wrong type. Without its tab, the weight narrows it to a pair, 87 g for the SX or SS and 81 g for the SR or SA, but does not tell the two types in a class apart. Frames from 1998 have aged, so check the head, the joint and the shaft closely.
Where the Swing Power idea went
The Swing Power Theory carried on for a few more years through the 500 and the Ti Swing Power: in 2003–05 Yonex Japan’s staff pages still listed the ISO-TIS for Zhou Mi, Roslin Hashim and Martin Lundgaard Hansen. The 900 itself soon gave way to titanium: the Ti-8 appeared beside it on Yonex Japan’s homepage in late 1998, the Ti10 arrived at ¥24,000 in spring 1999, and from mid-October 1999 the Ti10 was the only racquet the page promoted. The 900 remains the model that introduced the four-type system, and the one Yonex tied to Gong Zhichao’s first big title.
Check the shaft for ISOMETRIC SWING POWER 900 LONG and a colored type tab near the handle: red for SX, orange for SS, yellow for SR, blue for SA. Yonex’s ad shows navy frames with SQUARE SPOT lettered along the head, a gold shaft and JAPAN printed on the shaft. The weight should match the tab: Yonex listed 87 g (3U) for the SX and SS and 81 g (4U) for the SR and SA, with one grip shape for all four. A frame printed 500 with a silver shaft is the cheaper Swing Power 500, a black or orange frame with titanium mesh is the Ti Swing Power (2000–2005), and the 1992 Isometric 500 has no type tabs at all. Yonex published balance and flex per type only.
The Swing Power 900 is a collector’s piece for the idea it introduced: one model offered in four tuned types. Decide which type you want, then confirm the tab, the weight and the printed name. Gong Zhichao’s 1998 title is documented for the model only through Yonex’s own catalog, not for any individual frame, so treat claims of player provenance with caution.