Shock spring rate question????

[awilson40]

Why is free sag an issue? I have my race sag set at 95mm but have only about 3 mm of free sag, While my son's 95 KX125 is running 100 mm race sag and has 55mm free sag. So my spring is too light and his is too stiff. Can the springs be swapped between the two bikes(89 kx125 and 95 kx125)?
What is the real problem in having free sag to little or too great as long as race sag is correct?
Thanks

 

[marcusgunby]

running the wrong spring will mean the front fork angle will only be correct when you are sitting on the bike-as soon as you put a load on the forks ie braking, a too soft spring will allow the forks to dive into the stroke and give oversteer.Too stiff and you will get understeer.I think the 95 spring will go on the 89 but not the other way round.