Kim Hyo-joo won the Fortinet Founders Cup on the LPGA Tour. Kim finished at 17-under-par 271 on the final day of the tournament at Sharon Heights Golf and Country Club (par 72) in Menlo Park, California, on Sunday, edging out Nelly Korda of the United States by one stroke.
Kim is known for her precision-based style, but she also benefited from added distance in this tournament. Over the four rounds, she averaged 273 yards in driving distance. She trailed Korda (averaging 278 yards) by a mere five yards. While results can vary depending on which club a player uses on measured holes, in the fourth round alone, Kim drove 270 yards compared to Korda's 264, actually outdriving her rival.
According to Yonex Golf on Wednesday, Kim switched her driver shaft to the Yonex Kaiza Lite 4S ahead of this season's opening. She had previously used a 3X shaft of the same model. The 4S weighs 42 grams and the 3X weighs 39 grams. Both are ultralight, 10 to 20 grams lighter than standard shafts. A sheet of A4 copy paper weighs approximately five grams, meaning Kim's shaft weighs roughly the equivalent of just eight sheets of A4 paper.
Kim previously used shafts in the 50-gram range. She switched to the Kaiza Lite shaft starting in October 2024. Born in 1995 and now 31 years old, Kim has said she keenly felt that she could not survive on the LPGA Tour — where players in their 20s form the core — without recovering her declining driving distance.
One solution was to use a lighter shaft to increase swing speed. However, lighter shafts tend to flex too much, causing directional instability when swung aggressively.
It was then that Yonex Golf, Kim's equipment sponsor, released the Kaiza Lite shaft — ultralight yet with high rigidity. After switching to the shaft, Kim won the Ford Championship last March, ending a one-year-and-seven-month winless drought.
Ahead of this season, Kim switched again to the newly released 4S Kaiza Lite shaft. Kim reportedly made the change immediately, saying, "It feels heavier than the previous 30-gram-range shaft but with a softer flex, making it much easier to transfer power to the ball." In the Honda LPGA Thailand tournament in February — her first event after the shaft change — Kim's average driving distance was 255 yards, up 12 yards from 243 yards the previous year.
Yonex is one of the few club manufacturers that also produces its own shafts. This is thanks to decades of accumulated carbon technology, including the launch of the world's first carbon badminton racket. The Kaiza Lite shaft is praised for its outstanding rigidity and resilience. Multiple layers of extremely thin carbon fabric are wrapped uniformly, reducing thickness variation across the entire shaft while enhancing vibration absorption and strength.