I have Tracer 900 (FJ09) MY 2017. My weight is 95kg without gear. OEM front spring was too soft - > static and rider sag to big and rear spring is too hard -> static and rider sag too small. I have replaced front spring by Wilbers progresive with stiffness 8,5N/mm - 10,5 N/mm (free lenght 300mm) and changed oil (slightly thinner Wibers), set 10 clicks rebound out of closed and now the front end is better - front static sag 26, rider sag 46mm. The OEM rear is too hard - static sag 6-8mm only and rider sag 33-35mm. I would like to change rear spring to reach the right sag, but I am not sure what is stiffness of OEM rear spring (for M.Y. 2015 was 99,9N/mm, but I am not sure if M.Y. 2017 is the same). Could you advise? I found 95NM rear spring by K-Tech. I drive always without pillion, sometimes with light luggage (max. up to 20kg).