In 1973, Yamaha Motor developed the “Monocross suspension” and took the 250cc Motocross World Championship title. This suspension design would eventually become a standard for motorcycles worldwide.
Pioneering Bikes for the Dirt “Off-road Mania”
Ch. III – Evolution of the Monocross Suspension
https://global.yamaha-motor.com/showroom/offroadmania/ch3/