How To Set Sag:
This is the first step to finding a good suspension setup. Once sag is set it allows all of the other adjustments to do what they are designed to do. Give you comfort, confidence, and control. This process works for both the front and rear of the motorcycle. It is more accurate to use metric measurements if possible. (Photos are for display purposes only)
Step 1: Get a couple friends to help you. This is not something you can do easily by yourself and you don’t want to get it wrong.
Step 2: Determine the unladen suspension measurement. To do this you need to get the wheel off of the ground and measure from the axle to a fixed point on the body or frame. A center stand works the best as it’s easy to do both the front and rear. If you don’t have a center stand you can have your friends lift the bike, or on sport bikes in particular leaning the bike onto the side stand leveraging the wheel off of the ground is effective. We will call this dimension R1 for rear unladen. Make sure to put a piece of tape or some other mark so you measure to the same spot each time. For the front you need to raise the front wheel off of the ground so the forks are completely extended. Measure from the dust seal to the bottom of the triple clamp or to the axle for an upside down fork. This measurement is F1 for front unladen.
Step 3: Now repeat this process with the rider wearing their gear. Have a friend hold the bike so the rider can put his feet on the pegs. Have another friend take the same measurements as before marking them R2 for rear laden and F2 for front laden. It helps to have the same person take the measurements to add additional accuracy to the measurement.
Step 4: Subtract R2 and F2 from R1 and F1 respectively and you have your sag. Typical street bike sag is 30-35mm and race bikes are generally set to 20-30mm. These are recommended numbers and not cast in stone. Check where your setup is at and write it down before making changes. Test every time you make a change to see if it improved the ride. Remember the three cornerstones, comfort, confidence, and control. If you find that you cannot get the sag measurement close to these settings chances are your springs or either too soft or too hard for your weight.
Step 5: Sag is set by using the preload adjusters on the front fork and shock. Refer to your individual owners manual for how to adjust your specific motorcycles settings. If your bike lacks these adjustments you would need to replace the rear shock with one that has adjustments. The front forks often times can have new internals installed to give you the proper setup.
I hope that this helps many of you get started on the right path to a better suspension setup. In the coming weeks we will look at rebound and compression damping.