Sag is how much the suspension settles under your riding weight, statically, expressed as a percentage of total travel. As a reference, the fork usually runs 15-20% and the shock 25-30%. It's the foundation of all setup.

How do I measure sag?

Push the o-ring all the way down, get on the bike in the attack position (standing, not seated for the fork), settle carefully without bouncing, get off and measure how far the o-ring moved up the stanchion. Divide that by total travel to get the sag percentage.

Why is sag the foundation of setup?

Because it sets the starting point for pressure and suspension behaviour. Without correct sag, tuning rebound, compression or tokens is blind. Set sag first; the rest is calibrated afterwards to your taste and terrain.

Suspension & dropper cluster · Setup

How to set MTB suspension sag

Quick answer

Sag is how much the suspension settles under your riding weight, statically, as a percentage of total travel: the fork ~15-20% and the shock ~25-30%. You measure it like this: push the o-ring all the way down, get on the bike in the attack position, settle without bouncing, get off and measure how far the o-ring moved up; divide it by total travel. It's the foundation of all setup: with sag set, fork air pressure and whether it's too stiff make far more sense. We have a free sag calculator (Fox, RockShox and 132 models) to do the maths for you.

Before touching rebound, compression or tokens, set the sag. It's the starting point for the whole suspension.

What sag is and what to aim for

Sag is the static settle: how much the suspension gives under your riding weight alone, without pedalling or hopping. It's expressed as a percentage of travel. As a starting reference, the fork is usually set to 15-20% and the shock to 25-30%. These are guideline ranges; the rider calibrates within them according to terrain and style.

How to measure it, step by step

1 · O-ring down — Push the o-ring (the rubber seal on the stanchion) down to the lower stop, against the wiper. That way it marks the deepest point the suspension reaches.

2 · Get on in the attack position — Get on the bike in your riding gear. For the fork, stand on the pedals (not seated) in the attack position; for the shock, in the pedalling posture. Lean on a wall or have someone help you.

3 · Settle without bouncing — Set your weight carefully, without bouncing or moving the bike. The o-ring is pushed up the stanchion to where the sag reaches.

4 · Get off and measure — Dismount without touching the o-ring and measure how far it moved up the stanchion from the wiper. That distance is the static settle.

5 · Divide by travel — Sag % = settle ÷ total travel × 100. Compare it with the range (15-20% fork, 25-30% shock) and adjust pressure if needed.

How to measure sag: o-ring down, rider in attack position, o-ring travel up the stanchion and division by total travel — Sag is read off the o-ring: settle divided by total travel.

Why it's the foundation of everything

Sag sets the starting point for pressure and suspension behaviour. With correct sag, the next steps —fork pressure by weight, rebound, tokens— make sense. Without it, you tune blind. If the fork feels too stiff, the sag is almost always below the range.

Common mistake: measuring fork sag seated on the saddle, or bouncing on the bike. You have to settle your weight once, without bouncing, and in the right position; otherwise the o-ring moves too far and the sag comes out wrong.

Want to do the maths automatically?

Use our free sag calculator —Fox, RockShox, Öhlins and 132 calibrated models— or message us on WhatsApp

Frequently asked questions

What is sag?

How much the suspension settles under your weight, statically, as % of travel. Fork ~15-20%, shock ~25-30%. It's the foundation of setup.

How do I measure it?

O-ring down, get on in the attack position, settle without bouncing, get off and measure how far it moved; divide it by total travel.

Why sag first?

Because it sets the starting point. Without correct sag, rebound, compression and tokens are blind.

Fork pressure by weight → The fork is too stiff → Suspension & dropper cluster →

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BikeLab-pedia · Suspension & dropper cluster / Bicycle compatibility and standards / Carlos Eduardo Ravello Joo · BikeLab Studio · Trujillo, Peru