How to Set Motorcycle Suspension Sag (Dirt and Street)
Sag is how much the suspension compresses under the bike's weight and yours. It's the first setting to get right, and it changes how the bike turns, brakes and handles bumps.
Static sag vs race sag
Static sag is how far the bike settles under its own weight. Race sag, or rider sag, is how far it settles with you on it in your gear, in your riding position. Race sag is the one you set with spring preload. Static sag tells you if the spring rate is right.
How to measure it
- Put the bike on a stand so the rear wheel hangs. Measure from the rear axle to a fixed point on the fender or frame. That's fully extended.
- Take it off the stand and let it settle. Measure again. The difference is static sag.
- Sit on it in your gear, feet on the pegs, with a helper holding it upright. Measure again. The difference from fully extended is race sag.
- Adjust shock preload and measure again until race sag lands where you want it.
Typical numbers
- Full-size dirt bikes: race sag around 100 to 105 mm, static sag around 30 to 40 mm
- Street and sport bikes: often around 30 to 35 mm front and 25 to 30 mm rear
- Check your manual, since your model may list its own range
When preload isn't enough
If you set race sag correctly and static sag comes out too small, the spring is too soft for you. Too much static sag means it's too stiff. Either way, adding or removing preload won't fix it. You need the right spring rate for your weight.