If I recall correctly when you call and work with Dave for the Halgons he interviews you to understand your bike's weight ( if modified heavily) the type of riding you do and loads you expect and the mods you have made. Knowing this he is able to send you a set that are setup with the proper spring rate and recommended preload settings for your riding. 99% of the time they are spot on.
Women weighing 100-120 pounds, or Men, will need a substantially lighter spring than a 200 pound male rider with 105 pound wife riding two-up most of the time.