Motorcycle Suspension Sag Calculator
Calculate correct suspension sag for your motorcycle.
Get the right static and race sag for optimal handling.
Suspension Sag Analysis
Suspension sag is how much the bike compresses under its own weight (free sag) and under the rider’s weight (race sag / rider sag). Proper sag ensures the suspension works in its optimal range — not too stiff, not too soft.
Two measurements:
- Free sag (static sag): Bike on stand with no rider. Measures spring preload.
- Race sag (rider sag): Rider aboard in riding position. This is the key setup number.
Target race sag values:
- Sport/superbike: 25–30 mm rear, 30–35 mm front
- Naked / roadster: 30–35 mm rear, 35–40 mm front
- Adventure / dual-sport: 85–100 mm rear (longer travel)
- Cruiser: 30–40 mm rear
How to measure:
- Measure full extension (bike on paddock stand, wheel hanging free) = L1
- Measure under rider weight = L2
- Race sag = L1 − L2
Interpreting results:
- Race sag too HIGH (>target): Add preload (compress spring more)
- Race sag too LOW (<target): Reduce preload
- Free sag should be 5–10 mm (rear). If free sag is 0 with correct race sag, the spring rate is too stiff for rider weight.
Spring rate guide: A rough starting point is 1 N/mm of spring rate per 10 kg of total weight (rider + gear + luggage).