Gravity bikes have been on the scene for over 30 years, but they have yet to move from garage production to mass production. Although they are only working downwards in terms of function, their number is diligently "biting the knees", so it is only a question of time when production will move to the assembly line. Unofficial races are lined up around the world one after the other, which Tange saw as an opportunity that gave birth to the Yasujiro bike.