How to Set Your Sag — The Complete Guide

Sag is the amount your bike's suspension compresses under load. It is the single most important suspension measurement and the first thing you should check before making any other adjustment. If your sag is wrong, nothing else you do to your suspension will matter.

What Is Sag and Why Does It Matter?

When you sit on your bike in riding position, the suspension compresses under your weight. That compression is your sag. Proper sag ensures your bike sits at the correct ride height, which directly affects handling, traction, cornering, and stability. Too much sag and the bike squats too low, making it sluggish in turns. Too little and the bike sits too high, losing rear-wheel traction and making it nervous at speed.

The Three Types of Sag

1. Free Sag (Extended)

The measurement at full extension with the wheel off the ground. No load on the suspension. This is your baseline reference point.

2. Static Sag

The amount the bike settles under its own weight with no rider on it. Static sag should be approximately 6-10% of total available travel. This measurement tells you a lot about whether your spring rate is correct.

3. Race Sag (Rider Sag)

The amount the bike settles with you on board in full riding gear, in attack position. This is the measurement you tune to, and it's the number that matters most.

Target Sag Numbers

Here are the general rules of thumb used across the industry and by TBT Racing technicians:

• Front rider sag: 25-30% of available travel
• Front static sag: ~14% of available travel
• Rear rider sag: 30-34% of available travel
• Rear static sag: ~11% of available travel

For a typical bike with 12 inches (305mm) of rear travel, that means rear race sag should be around 100-105mm for motocross, or 105-110mm for enduro. Front race sag is generally about half of your rear sag number.

How to Measure Rear Sag

You will need a tape measure, a friend to help hold the bike, and your full riding gear.

1. Get your fully extended measurement (L1): Put the bike on a stand with the rear wheel off the ground. Measure from the rear axle straight up to a fixed point on the subframe or fender bolt. Write this number down.
2. Get your rider sag measurement (L2): Take the bike off the stand. Put on all your riding gear. Sit on the bike in attack position — stand on the pegs, then sit down gently. Bounce lightly and let the bike settle. Have your friend measure the same two points.
3. Calculate: Race Sag = L1 - L2
4. Static sag:Same process, but without a rider — just the bike's own weight settling the suspension.

How to Adjust Sag

• Too much sag? Increase spring preload by tightening the preload ring.
• Too little sag? Decrease spring preload by loosening the preload ring.
• Preload at extremes and sag is still wrong? You need a different spring rate entirely. No amount of preload adjustment can fix an incorrect spring.

What Sag Tells You About Your Springs

Sag is not just a setup number — it is a diagnostic tool for your spring rate:

• If static sag is less than 15-20mm with correct race sag, your spring is too stiff.
• If static sag is more than 40mm with correct race sag, your spring is too soft.
• If you cannot achieve correct race sag at any preload setting, you have the wrong spring rate.

“Think about if you bought a car that came with a seat that was non-adjustable. Everybody's body is a different height and different weight. These bikes are produced for an elusive average rider.” — Travis Flateau, TBT Racing

Common Sag Mistakes

• Measuring without gear: Your helmet, boots, chest protector, and hydration pack add 10-15 pounds. Always measure in full riding gear.
• Not bouncing first: Stiction in the suspension gives false readings. Bounce gently before settling to break the seals free.
• Using the wrong reference points: Always measure from the axle to a fixed point on the frame — not the fender, seat, or any plastic that can flex.
• Compensating with preload instead of springs: If your preload collar is cranked way up or barely touching the spring, you need a different spring rate. As Travis Flateau says: most tuners try to avoid selling you new springs by over-compensating with preload and valving. TBT Racing always addresses the spring first.

When to Re-Check Sag

You should re-check your sag any time your weight changes by more than 5 pounds, when you switch riding disciplines (motocross to enduro), after installing new springs, after a suspension service, or at the start of every racing season. It takes five minutes and it is the highest-impact adjustment you can make.