Quote:
Originally Posted by Frank_drebbin
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pretty much except that you
dont adjust for rider sag. this is the biggest common mistake that people make because they dont want to face the fact that the spring rate is wrong.
you check and then
set static sag to 10mm for road use.
you then put the rider on and
check the rider sag 30-40mm.
lets say:
bike off ground (free sag) 500mm
your static sag (bike on ground and upright) should be as near to 510mm as possible for road use.
your rider sag (bike on ground and upright with rider) should be 530-540 with nearer the higher number better for road use.
if the rider sag does not fall in between the 530-540mm range then you need to change the springs.
do not wind the preload up or down to match the rider.
always
SET static sag and leave it there. changing the rider sag with using the preload will also change the static sag.
however, lets say if you have a rider sag of 545mm and a static sag of 10mm you can wind the preload down by 5mm to achieve the correct numbers. the only problem with this is that you are now going into race setup settings which are no good for road use.
the above is also true in the opposite direction. lets say your static sag is 10mm and the rider sag is 525mm you cant add 5mm to the static sag to increase the rider sag as the static sag would then be 15mm.
a few mm here or there is not going to make that much odds in the grand scheme of things so dont fret too much about numbers as long as your not getting wildly large increases/decreases.
why do you need static sag?
simple, during braking in particular if you dont have a negative number then your suspension "tops out" too soon so more inclined to lift the rear wheel off the ground during braking. this then upsets the chassis for corner entry and or emergency stops. with race settings things are a lot more precise and the front setup is matched to the rear using stiffer spring rates.