Whether you are a road rider or a racer, correct suspension setup is the key to smooth, comfortable riding or consistent lap times. To get the best out of your bike it needs to be set up for the conditions in which you will be riding, with correct spring rates for your bike. As most bikes are made for small guys, changes are usually needed with the springs.
First you will need to check the Fork and Shock sag: this is the amount the forks and rear shock settle under load. To measure it do the following: With a couple of friends helping, fully extend the front suspension and measure from the fork seal to the bottom triple clamp (for conventional forks) or from the seal to the fork bottom. Note this measurement as something like Sag-1.
Put on your regular riding gear and hop on your bike, in your normal riding position. Have a friend hold the rear of the bike so that you can keep both feet on the pegs. Your second pal needs to take the same measurement as in step one-once after pushing down on the front end and slowly letting it settle up (Sag-L2), and again after lifting the front end and letting it settle down (Sag-3).
Static sag is calculated as: Sag1-(Sag3+Sag2)/2. Averaging the two measurements with you sitting on the bike negates any stiction that may be present. Aim for approximately 25-30mm of static sag for street riding . If you have too much sag, tighten up the front preload. Too little, and you'll have to loosen the adjusters accordingly. Generally, one turn on the adjuster will usually change sag by about one millimeter.
On the rear of the bike, extend the suspension and measure from the axle to a solid point directly above. Try to avoid measuring to bodywork, as it tends to move and flex when you lift the rear end or sit on the seat. Instead, measure to a point on the subframe (or something solid). As before, this measurement is Sag-1.
Repeat steps two and three, with one person holding the front of the bike while the other takes the two measurements at the rear. 20-25mm of sag is a good starting point for street riding,
If you can’t get the sag numbers within that range, more than likely you need to change springs ( front, rear or both).
