Mountain Race Shop™ — Shim Calculator

Rider & Bike Setup

Rider mass (kg, with gear)

Bike mass (kg, wet)

Front balance (%)

Discipline / Use

Damping ratio (ζ)

Fork spring rate (N/mm)

Fork preload (mm)

Fork wheel travel (mm)

Fork oil level (mm from top)

Fork oil viscosity (ISO VG)

Fork inner tube dia (mm)

Fork cartridge type

Fork gas pressure (bar)

Shock spring rate (N/mm)

Shock gas pressure (bar)

Shock preload (mm)

Shock shaft stroke (mm)

Shock oil viscosity (ISO)

Digressive knee (m/s)

High-speed slope (0.1–1.0)

Soft spread (% default 7.5)

Stiff spread (% default 7.5)

Then go to Simulate tab for full calculation & recommendations

Fork Dyno Data — Base Comp & Rebound

Enter positive force (N) for both compression and rebound. Rebound is plotted negative automatically.

Drag CSV here or click to upload (velocity m/s, force N)

V (m/s)	Base Comp (N)	Rebound (N)

Fork Shim Stacks

Base Valve — Compression

Seat dia (mm)

1st shim is bleed?

Recommend with bleed?

Bleed holes

Dia (mm)	Thk (mm)	Qty

Low-Speed Valve (LSV) Adjuster

Has LSV?

LSV seat dia (mm)

Clicks out (from hard)

Total clicks

Dia (mm)	Thk (mm)	Qty

Mid Valve — Compression

Seat dia (mm)

Float (mm)

Stack type

Bleed holes

Dia (mm)	Thk (mm)	Qty

Rebound

Seat dia (mm)

Stack type

Bleed holes

Dia (mm)	Thk (mm)	Qty

Shock Dyno Data — Comp & Rebound

Enter positive force (N) for both. Rebound plotted negative.

Drag CSV here or click to upload (velocity m/s, force N)

V (m/s)	Comp (N)	Rebound (N)

Shock Shim Stacks

Piston bleed holes (affects both comp & reb)

Bleed holes drilled through the shock piston affect both compression and rebound circuits. Enter once here — the calculator applies it to both.

Compression — Main Stack

Seat dia (mm)

1st shim is bleed?

Recommend with bleed?

Bleed holes

Dia (mm)	Thk (mm)	Qty

Compression Adjuster

Has adjuster?

Adjuster seat dia (mm)

Clicks out (from hard)

Total clicks

Dia (mm)	Thk (mm)	Qty

Rebound

Seat dia (mm)

1st shim is bleed?

Recommend with bleed?

Bleed holes

Dia (mm)	Thk (mm)	Qty

Suspension Simulation

Select a track/terrain profile and run the simulation to see how your suspension responds. The animation shows fork and shock travel in real time with bottoming and force warnings.

Track / Terrain

Sprung mass (kg)

Spring rate (N/mm)

Travel (mm)

Rider skill

Upload custom track CSV (time s, vertical velocity m/s)

Ready

Fork & Shock Animation

Warnings

Run a simulation to see warnings.

Optimizer Results

Click "Optimize" to compare your stack vs recommended/soft/stiff on the selected track.

Contribute Your Telemetry

Share your track data with the community. Your name will be credited on the track.

Drag your telemetry CSV here or click to upload

Your name

Track / Location

Discipline

Description

I agree to share this data with the Mountain Race Shop community. My name will be credited on the track listing.

Rider & Bike Setup

Fork Dyno Data — Base Comp & Rebound

Fork Shim Stacks

Base Valve — Compression

Low-Speed Valve (LSV) Adjuster

Mid Valve — Compression

Rebound

Shock Dyno Data — Comp & Rebound

Shock Shim Stacks

Compression — Main Stack

Compression Adjuster

Rebound

Suspension Simulation

Fork & Shock Animation

Warnings

Optimizer Results

Contribute Your Telemetry

Calculation Report