The Importance of Motorcycle Sag
How to Set Motorcycle Sag—and Why It Matters for Every Ride
Before you start shopping for a new shock or turning every adjuster on your forks, there’s a good place to begin: setting the motorcycle up for the person riding it.
You.
Your weight, riding gear, passenger, and luggage all influence where the bike sits in its suspension travel. Getting that starting position right helps the suspension do its job and gives you a better foundation for everything that follows.
That’s where sag comes in. Whether you’re commuting, chasing a clean lap, or heading down a dirt road, it deserves some attention.
What is rider sag?
Rider sag is how far the suspension settles from fully extended with you on the motorcycle, wearing your riding gear.
Free sag is how far it settles under the motorcycle’s own weight, without you aboard. We’ll use those two terms here because “static sag” gets used differently depending on who you ask.
Why should the suspension settle at all? Because your wheels need room to move in both directions. The suspension compresses over a bump, but it also needs to extend into a dip and follow the surface as the bike unloads.
Too much sag uses up compression travel before you’ve even started riding. Too little leaves less room for the wheel to extend. The balance between front and rear also influences the bike’s stance and how it steers.
The goal is to give your motorcycle room to work.
How to measure it
You’ll need a metric tape measure, or if you’re fancy like me, (I love supporting fellow industry!) and the Slacker Sag tool is one of the best devices made for this. Then a way to safely support the bike with the suspension unloaded, your riding gear, and some help. Two helpers make this easier: one to balance the motorcycle and one to measure.
Start on level ground, note your existing settings on paper or in “The Suspension Lab” app we’ve created releasing November 2026, and check the setup instructions for your motorcycle or aftermarket suspension.
1. Measure with the suspension fully extended
Support the motorcycle using suitable lifting equipment so the suspension being measured is unloaded. A rear paddock stand under the swingarm does not unload the rear suspension.
For the rear, measure from the axle center to a repeatable point on the chassis or firmly mounted bodywork, approximately above the axle. Mark that point with painters tape and a sharpie mark so it’s repeatable.
For a conventional telescopic front fork, measure between a point on the lower assembly and a fixed point on the upper assembly, following the direction of fork movement. Use the same points every time. Alternative front suspension designs need their own procedure.
Record these fully extended measurements as A. (racetech.com, ohlins.com)
2. Measure the motorcycle on its own
Put both wheels on the ground and hold the bike upright without adding weight.
Gently compress the suspension and let it settle slowly, then measure. Lift it slightly, let it settle again, and take another measurement. Average those two readings to reduce the effect of friction.
Record that average as B.
3. Measure with you aboard
Put on your normal riding gear and take your riding position, with your feet on the pegs and your weight supported by the motorcycle. Your helper should balance it without lifting or pushing down.
For a road bike, sit where you normally ride. For dirt bikes, follow the position specified by the setup guide; some procedures call for standing on the pegs. Consistency matters.
Repeat the gentle settling process and average the readings. Record this as C.
4. Calculate the difference
Free sag = A − B
Rider sag = A − C
For example, a fully extended measurement of 600 mm and a rider-loaded measurement of 565 mm gives 35 mm of rider sag. That’s an example of the calculation, not a target for every motorcycle.
Repeat the process at both ends. Rider sag is measured from full extension—not simply from the bike sitting on the ground before you climb aboard.
Adjusting sag: what preload actually does
On a coil-spring suspension, preload changes how much the spring is compressed before the suspension carries its load.
Generally, adding preload reduces sag; removing preload increases sag. It does not change the rate of a straight-rate spring or convert an unsuitable spring into the right one. In fact, chasing the correct number you found online with the wrong spring rate can actually compromise and hurt your motorcycles performance, and this is where a qualified suspension tuner is worth their weight in gold.
Identify the preload adjuster using your manual. It might be a fork-cap adjuster, threaded shock collar, stepped collar, remote knob, or electronic control. Use the correct tool, follow any unloading instructions, and stay within the permitted range. Most dirt and some adventure bikes have their preload controlled internally and it must be set by the tuner installing your springs.
*Always consult your manual for adjustments - Beta Motorcycles for instance specifically calls for adjusting their ZF shock preload on many of their models by removing the shock first. Many riders have been tempted to adjust with a drift and a punch, but the two piece body utilized on this particular shock is known to spin and separate, degassing the shock and losing its charge and fluid. I’ve serviced more of these for this reason than any other.
Make small changes, record them, and remeasure. Where both fork legs have matching preload adjusters, normally adjust them equally unless the manufacturer specifies otherwise. Some forks can also have different functions in each leg, so pay attention.
If there’s no external preload adjustment, don’t start removing caps or adding spacers just to chase a number. That’s the point to assess the spring and available options. Öhlins likewise notes that adjustment availability and setup requirements depend on the specific kit.
Why there isn’t one perfect sag number
A short-travel cruiser and a long-travel enduro bike have very different amounts of suspension movement to work with. Even motorcycles in the same category can need different settings.
Here’s what changes the conversation:
Street, naked, and sport bikes: Real roads demand room to absorb uneven pavement while maintaining a balanced stance.
Track bikes: Sag is a starting point. Braking support, available travel, geometry, and rider feedback still need evaluation.
Adventure and dual-sport bikes: Luggage, passengers, and changing terrain make load-specific setup especially important.
Motocross and enduro bikes: Use the model’s recommended procedure and targets, including the specified rider position.
Supermotos: Wheel conversions, lower lug changes, suspension lowering, and pavement-focused use can make the original dirt-bike settings inappropriate, and dysfunctional for that type of riding.
Cruisers and touring bikes: Limited travel and passenger weight deserve particular attention. On matching twin-shock systems, follow the manufacturer’s instructions for setting both sides and correct spring rate becomes the most important part of the setup.
Start with guidance for your exact motorcycle and installed suspension. For example, Legend Suspension provides specific sag and matched-preload instructions for its applicable shocks, including rechecking when the load changes. Those figures shouldn’t be carried over to unrelated equipment.
What about electronic suspension?
Follow your model’s setup procedure before measuring or adjusting. The required ignition state, load mode, and automatic-leveling behavior can differ.
Electronic damping, electronic preload, and automatic ride-height control are different functions. A “Sport” setting alone doesn’t tell you whether the motorcycle has adjusted its support for you and your luggage.
If you’re unsure what your system actually controls, that’s worth sorting out and investigating before changing settings.
When the measurements deserve a closer look
Getting rider sag into range is only part of the picture. Free sag, the amount of preload required, and how consistently the suspension settles help us judge whether the setup makes sense.
If an adjuster is at its limit, the readings won’t repeat, or the bike still feels unsettled, keep investigating before buying parts. The answer might involve spring selection, friction, servicing, damping, or chassis balance.
And if you regularly switch between riding solo and carrying a passenger, record separate settings where your system allows it. One setup won’t necessarily suit both loads.
Free sag: checking the spring
Once rider sag is where you want it, take one more look at free sag. It tells you whether the spring actually suits you.
If rider sag is right but free sag comes out bigger than your bike's recommended figure, the spring is likely too stiff. You had to take preload off to get rider sag into range, so the bike now sinks further under its own weight.
If free sag comes out too small, the spring is likely too soft. It's preloaded so far into its travel just to hold you up that there's little left for the bike to settle under its own weight. That can cost you usable travel and hurt the way the bike handles.
Always set rider sag first, then check free sag. The two numbers together tell you more than either one alone. If they don't agree, adjusting preload won't fix it. That's the point to look at a different spring rate, and a qualified suspension tuner can help you choose one.
Start with the motorcycle you already have
A proper setup gives you a useful baseline. From there, take a measured test ride and pay attention to how the motorcycle steers, handles bumps, and responds when you brake.
You don’t need to know all the terminology. “It runs wide,” “the front feels vague,” or “it gets harsh over broken pavement” is useful feedback.
At 91 Octane Suspension, that’s where the conversation starts: what you ride, how you use it, and what you’re feeling. We look at sag alongside the adjustments and equipment already on your motorcycle, then help you understand what’s working and what needs attention.
For riders in San Luis Obispo County, we offer personalized suspension setups based on your motorcycle, riding gear, and how you actually ride.
If you’d like a hand, reach out to arrange a suspension setup. Bring your usual riding gear and tell us about the rides you enjoy.
The aim is simple: a motorcycle you feel more comfortable, connected, and confident riding.