Motorcycle Suspension Sag Measurement

Method and units

Free sag = fully extended length − bike-only length. Rider sag = fully extended length − rider-loaded length. Percentage of travel = sag ÷ entered travel × 100. Apply independently to front and rear measurements.

Worked example

With 120 mm front travel, 600 mm extended and 570 mm rider-loaded measurement, rider sag is 30 mm or 25% of travel. A 300 mm rear measurement from 500 to 455 mm gives 45 mm.

Supported inputs and interpretation

Travel 1–500 mm; measurements 1–2,000 mm; loaded and bike-only lengths cannot exceed fully extended length. Results are rounded for display only; internal calculations retain full JavaScript precision. Entered measurements and assumptions determine the answer.

References and limitations

The equations here use the stated unit conversions and geometric or accounting relationships; no empirical vehicle limits or manufacturer presets are supplied.

The measurement points and technique must be consistent; stiction, linkage ratio and repeated settling affect results. No universal target is asserted. Consult the motorcycle maker's setup procedure and have changes checked by a qualified technician; measurements do not approve modifications.

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This planner performs the stated arithmetic; it is not a vehicle inspection, engineering approval, manufacturer's recommendation or professional review.