Just fitted custom made Cannon Racecraft Springs on my Honda XR400R. A while ago I had ordered Eibach springs and the seller asured me that with 47kg spring rate for the forks I would be good. It was an improvement over the stock but I still wasn't happy enought and I wanted something better then that set-up. I searched all kind of spring rate calculators over the net. Try to get more info with racetech, but couldn't find anything suitable until I found Cannon Racecraft, those guys replied very quick to my first email and gave me very professional advise about the spring rates, as the springs I needed weren't available they were manufacured for my weight. I got 64kg spring rate for the forks and 13.6kg for the rear shock, I installed the springs a couple of days ago. The springs transformed the XR400R into a rocket, now I can go much quicker over ruts and roots without loosing traction, the fork flex is completely eleminated and the overall handling has 100 % improved. I am very happy with this set-up now. I will take the bike on some more rides to fine adjust the suspension and will get back with more info then. For now I am just so grateful. Thanks a thousand times to Cannon Racecraft