Motorcycle Suspension Sag Calculator

Why Suspension Sag Matters

Setting the correct suspension sag is one of the most crucial steps for optimising your motorcycle's handling, stability, and safety. Sag is the amount your suspension compresses under the weight of the bike itself (static sag) and with you, the rider, aboard (rider sag).

  • Too little sag: Can make the ride harsh, reduce traction over bumps, and cause instability.
  • Too much sag: Can lead to wallowing, poor steering response, bottoming out, and reduced ground clearance.

This tool helps you measure and calculate your sag, comparing it to generally recommended ranges for different types of riding. Always consult your owner's manual or a suspension professional for model-specific recommendations.

How to Measure Sag (in Millimeters)

You'll need a tape measure (metric), a helper, and your usual riding gear.

Front Suspension Measurement Steps
  1. Fully Extended: Lift the front wheel completely off the ground (e.g., using a front stand that lifts from the lower triple clamp). Measure the distance from the dust seal (or fork bottom) to the axle clamp (or axle center). This is your fully extended length (F1).
  2. Static Sag: Take the bike off the stand and let it rest under its own weight on level ground. Gently push down on the handlebars and let the suspension settle slowly. Measure the same points as in step 1. This is the static length (F2).
  3. Rider Sag: Put on your usual riding gear. Sit on the bike in your normal riding position with your feet on the pegs (have your helper balance the bike). Bounce gently and let the suspension settle. Have your helper measure the same points again. This is the rider length (F3).
Rear Suspension Measurement Steps
  1. Fully Extended: Lift the rear wheel completely off the ground (e.g., using a center stand or paddock stand that lifts the frame, not the swingarm). Measure the vertical distance from the axle center to a fixed point directly above it on the tail section or subframe. Mark this point if needed. This is your fully extended length (R1).
  2. Static Sag: Take the bike off the stand and let it rest under its own weight on level ground. Gently push down on the seat and let the suspension settle slowly. Measure the same points as in step 1. This is the static length (R2).
  3. Rider Sag: Put on your usual riding gear. Sit on the bike in your normal riding position with your feet on the pegs (have your helper balance the bike). Bounce gently and let the suspension settle. Have your helper measure the same points again. This is the rider length (R3).

Calculator

Front Suspension Measurements (mm)
Rear Suspension Measurements (mm)

Results

Front Suspension

Static Sag: -- mm

Rider Sag: -- mm

Rear Suspension

Static Sag: -- mm

Rider Sag: -- mm

Note: These are general recommendations. Fine-tune based on feel, preference, and specific bike/track/trail conditions. Rider sag is generally the primary tuning target.

Use measurements as a guide; professional tuning is recommended.

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