Sag is the first thing you set and the reason most bikes feel wrong. Three measurements, ten minutes, and it decides whether every other adjustment you make is worth anything.
Race sag is how far your bike settles into its suspension when you sit on it in full gear. It is not a comfort setting. It sets the bike's ride height, and ride height sets the head angle, and the head angle decides whether the bike turns, whether it holds a line, and whether it tries to shake its head at you down the straight.
It also decides where in its stroke the shock is sitting when you start riding. A shock that begins its work in the wrong part of its travel behaves badly everywhere, and no amount of clicker fiddling will talk it out of that.
This is why sag comes first. Chase clickers on unknown sag and you are guessing with extra steps. Correct the sag afterwards and every clicker change you made gets undone, because you have just moved the geometry those changes were compensating for.
You need a tape measure marked in millimetres, a spanner wrench for the preload collar, and a second person. You cannot measure L3 accurately on your own — balancing the bike changes what you are measuring.
Every measurement runs between the same two points: the centre of the rear axle and a fixed mark on the rear fender directly above it. Mark it with a paint pen. Same two points, every time, or the numbers are fiction.
| Measurement | Motocross | Off-road / trail |
|---|---|---|
| Race sag | 100–105 mm | 105–110 mm |
| Static sag | 30–40 mm | 30–40 mm |
Off-road runs slightly more sag on purpose. A softer, lower-sitting rear helps traction on unpredictable ground and takes some of the edge off square hits at trail speed, where you are not carrying enough momentum to make a stiff setup work.
Adjust race sag with the preload collar on the shock. Too much sag means the bike is sitting too low, so add preload. Too little means it is riding too high, so back the collar off. Re-measure after every change, and expect to go back and forth a couple of times.
Preload is not spring rate. Winding the collar in does not make the spring stiffer. It only changes where the spring starts from. That distinction is the whole reason static sag matters.
This is the part most riders skip, and it is the most useful number on this page.
Once race sag is correct, static sag tells you whether the spring itself is right for your weight. The logic is simple: if you need a huge amount of preload to reach correct race sag, the bike will barely settle at all under its own weight, and static sag comes out tiny. That is a spring that is too soft, being propped up by preload.
| Static sag (with race sag correct) | What it means |
|---|---|
| Under 25 mm | Shock spring is too soft for you. You are carrying the bike on preload. |
| 25–30 mm | On the soft side. Rideable, but a stiffer rate would be better. |
| 30–40 mm | Spring rate is right for your weight. |
| 40–45 mm | A touch stiff. |
| Over 45 mm | Spring is too stiff. The bike will feel harsh and won't settle in corners. |
A wrong spring rate cannot be clicked out. Clickers control damping — how fast the suspension moves. The spring controls how far it moves and how hard it pushes back. If the rate is wrong, every clicker setting is a compromise between two bad options, and you will spend a season never quite finding it.
If static sag says your spring is wrong, that is the job. Not the clickers. See spring rates by rider weight for where you should be.
One caveat worth stating plainly: measure static sag after race sag is correct, not before. Before, it tells you nothing — it is just a number produced by whatever preload happens to be on the bike right now.
Punch in L1, L2, and L3. MXDialed works out race sag and static sag, checks both against the window for your discipline, and tells you straight out if your spring rate is the actual problem.
Open the sag calculator →Free, no signup, works on a phone at the track.
Sag correct and spring rate confirmed is the point where clicker adjustments start to mean something, because you are now tuning damping rather than compensating for geometry.
Only one thing outranks it: worn suspension oil. Fork oil past roughly 30 hours and shock oil past roughly 40 is contaminated and foaming, and a tired fork feels almost exactly like a badly set up one. If your sag is right, your spring is right, and the bike still feels dead, the answer is a service, not a setting.
100–105 mm for motocross, 105–110 mm for off-road and trail, measured with the rider in full gear. A few models specify their own window, so check your manual — where it disagrees with a general figure, the manual wins.
L1 and L2 yes. L3 no — holding the bike upright yourself changes your weight distribution and the reading. Get a second person for that one measurement.
It exists, but it is a far weaker diagnostic than rear sag and most riders never measure it. Fork spring rate is better judged by how the fork behaves — diving under braking, bottoming on jump faces, or feeling harsh across chop — and by matching the rate to your geared weight.
Try taking 2–3 mm of sag out, which lifts the rear and steepens the head angle, or raising the forks in the clamps 2–3 mm, which drops the front and does the same thing. Both make the bike fall into corners more willingly. Change one, ride it, then decide.
Any time your geared weight changes, after a shock service or spring swap, and at the start of every season. Springs take a set over time, so last year's number is not automatically this year's.