The Suzuki factory manual is kinda cryptic about where the measurement is to be taken as well... the way I set up my rear spring preload is to have someone hold the bike upright while I measure the distance from the axle to a point on the frame... and then when I sit on the bike I want it to sag(the measurement decreases) between 1" and 1 1/2" with just my weight on the bike... don't use a stand to do this, or it will change the measurement. You can make the sag whatever seems to suit your comfort level/riding style... Try out setting it to 1 1/4" and ride it around some and see how it feels. compress the spring more to get less sag, compress it less to get more sag. I always figured that the spring preload was just for setting the ride height, and the soft/hard settings were all taken care of with the damping force adjusters ...hope that helps.