Öhlins MTB Coil Spring Calculator
Estimate a starting rear shock spring rate (N/mm and lb/in) for your MTB setup.
How this Öhlins MTB spring calculator helps
If you are trying to choose the right Öhlins coil spring for MTB, this tool gives you a practical baseline in seconds. You enter rider and bike details, target sag, and shock dimensions, and it returns:
- Estimated required spring rate in N/mm
- Equivalent spring rate in lb/in
- Nearest common Öhlins-style spring option
- A preload recommendation to keep your setup in a healthy tuning range
Why spring rate matters on a coil shock
Spring rate drives your ride height, support, traction, and mid-stroke behavior. Too soft and the bike dives deep into travel, pedals poorly, and bottoms frequently. Too stiff and the rear end feels harsh, loses grip, and skips over roots and chatter.
For riders using Öhlins TTX series shocks, getting the spring close on the first try saves time and money. You can still fine tune with compression and rebound damping, but damping cannot fully fix a spring that is far off target.
Quick setup workflow after choosing a spring
1) Install spring and set preload correctly
Start with minimal preload. As a rule of thumb, coil preload is usually kept small. If you need excessive preload to hit sag, your spring is likely too soft. If you need almost no preload and still sit too high, it is likely too stiff.
2) Set sag on the trail in riding position
Check sag in your normal attack stance, with the same pack, water, and equipment you entered in the calculator. This keeps your data consistent.
3) Tune damping after spring is correct
Only after spring rate and sag are close should you adjust low-speed compression, high-speed compression (if available), and rebound. That sequence gives cleaner, repeatable tuning.
Formula used by this MTB spring rate calculator
This calculator estimates required shock force at sag from rider/bike load and frame leverage. It then computes spring rate from force and shock compression at target sag.
- Leverage ratio = wheel travel / shock stroke
- Shock sag (mm) = shock stroke × sag%
- Required spring rate (N/mm) = (rear wheel load force × leverage ratio) / shock sag
- Conversion: 1 N/mm = 5.7101 lb/in
It is a starting-point model, not a lab-grade measurement. Real bikes have progressive leverage curves, stiction, seal drag, and rider movement that affect final choices.
Common mistakes when choosing an Öhlins MTB spring
- Using bodyweight without gear or hydration
- Ignoring different riding posture between climbing and descending
- Trying to fix spring issues only with damping
- Comparing spring rates across bikes with very different leverage curves
- Not checking sag after changing tire pressure, inserts, or cockpit setup
Practical tuning tips for trail, enduro, and bike park
Trail riding
A balanced setup usually lands around 27-30% rear sag for all-day traction and efficiency.
Enduro racing
Many riders prefer 28-32% sag depending on terrain roughness, frame progression, and support preferences.
Bike park / gravity days
You may run slightly more support via spring or low-speed compression for repeated hits and big compressions, but keep grip as the priority.
Final note
This ohlins spring calculator mtb is designed as a reliable first step for selecting your rear coil spring. Use it to narrow down options, then validate on trail with real sag checks and repeatable test runs. If your frame has an unusually progressive or regressive leverage curve, consult your bike manufacturer and Öhlins service resources for model-specific guidance.