*Note: Ohlins springs are typically available in 4lb or 2lb increments. Round to the nearest available size based on your riding preference (stiffer for jumps/racing, softer for technical traction).
Why Finding the Correct Ohlins Spring Rate Matters
Ohlins suspension is world-renowned for its "Gold Standard" performance, but even a TTX or STX shock cannot perform correctly if the spring rate is incorrect. The spring rate determines the initial resistance and supports the weight of the rider and bike.
Key Factors in the Calculation
Leverage Ratio: This is the relationship between how much the rear wheel moves compared to how much the shock moves. A bike with 150mm travel and a 50mm stroke shock has a 3:1 leverage ratio.
Rider Weight: Always measure your weight including your helmet, boots, jersey, and hydration pack. This "ready-to-ride" weight is usually 15-20 lbs heavier than your street weight.
Target Sag: For most enduro and downhill bikes, 28% to 33% sag is ideal. For cross-country or street bikes, 20% to 25% provides a firmer platform.
Real-World Example
If you weigh 190 lbs with gear, ride a bike with a 160mm travel frame and a 65mm shock stroke (2.46 leverage ratio), and want 30% sag, your calculated spring rate would be approximately 450 lbs/in. If you find yourself bottoming out frequently, you might step up to a 475 lbs/in Ohlins spring.
How to Verify Your Spring
Once you install your recommended Ohlins spring, measure your actual sag. If you need more than 2 full turns of preload to achieve the correct sag, your spring is likely too soft. If you achieve correct sag with zero preload, your spring may be too stiff.
function calculateSpringRate() {
var riderW = parseFloat(document.getElementById('riderWeight').value);
var bikeW = parseFloat(document.getElementById('bikeWeight').value);
var weightUnit = document.getElementById('weightUnit').value;
var wheelTravel = parseFloat(document.getElementById('wheelTravel').value);
var shockStroke = parseFloat(document.getElementById('shockStroke').value);
var targetSag = parseFloat(document.getElementById('targetSag').value);
var linkage = document.getElementById('linkageType').value;
if (isNaN(riderW) || isNaN(bikeW) || isNaN(wheelTravel) || isNaN(shockStroke) || isNaN(targetSag)) {
alert("Please enter all values to calculate the spring rate.");
return;
}
// Convert weight to lbs if it's in kg
var totalWeightLbs = (weightUnit === 'kg') ? (riderW + bikeW) * 2.20462 : (riderW + bikeW);
// Leverage Ratio
var leverageRatio = wheelTravel / shockStroke;
// Weight Distribution (Approx 65% on rear for MTB/Moto)
var weightOnRear = totalWeightLbs * 0.65;
// Target Sag in Inches
var strokeInches = shockStroke / 25.4;
var targetSagInches = strokeInches * (targetSag / 100);
// Base Calculation: Rate = (Force) / Displacement
// Using the leverage ratio squared for force translation in a suspension system
var rate = (weightOnRear * leverageRatio) / targetSagInches;
// Adjust for linkage type
if (linkage === 'progressive') {
rate = rate * 0.95; // Can run a slightly softer spring because linkage gets stiffer
} else if (linkage === 'regressive') {
rate = rate * 1.05; // Needs more support early on
}
// Convert to N/mm (1 lb/in = 0.175127 N/mm)
var rateNmm = rate * 0.175127;
// Display results
document.getElementById('resultsArea').style.display = 'block';
document.getElementById('rateLbs').innerText = Math.round(rate) + " lbs";
document.getElementById('rateNmm').innerText = rateNmm.toFixed(1) + " N/mm";
// Scroll to results
document.getElementById('resultsArea').scrollIntoView({ behavior: 'smooth', block: 'nearest' });
}