Finding the correct spring rate is the single most important step in setting up your motorcycle's suspension. Whether you are hitting the track or touring across the country, an Ohlins shock is only as good as the spring attached to it. Use our calculator below to find your recommended rate.
*This is an estimate based on average leverage ratios. Always consult your specific Ohlins manual for exact fitment.
Why Spring Rate Matters for Performance
The spring rate determines the amount of force required to compress the spring by a specific distance (usually measured in Newtons per millimeter, or N/mm). If your spring is too soft, the suspension will sit too low in its stroke, causing poor geometry and frequent bottoming out. Conversely, a spring that is too stiff will prevent the suspension from tracking the ground effectively, leading to a harsh ride and loss of traction.
Understanding N/mm vs. Lbs/in
Ohlins, being a Swedish company, primarily uses the metric system for their spring markings. You will often see numbers like "1091-31/95". In this nomenclature:
- 1091: Refers to the physical dimensions (length and diameter).
- 31: Is the internal production code.
- 95: Is the rate (95 N/mm).
To convert N/mm to lbs/in, you multiply the N/mm value by 5.71. For example, a 100 N/mm spring is approximately 571 lbs/in.
Factors That Influence Your Calculation
While a calculator provides a baseline, several real-world factors can shift your needs:
1. Total Loaded Weight
When calculating your weight, you must include your helmet, leathers, boots, and gloves. This typically adds 7kg to 12kg (15-25 lbs) to your body weight. If you frequently carry a pillion passenger or heavy luggage, you may need a hydraulic preload adjuster or a significantly stiffer spring.
2. Linkage Leverage Ratio
Every motorcycle has a different "leverage ratio"—the relationship between rear wheel travel and shock travel. A bike with a 2:1 ratio requires a much softer spring than a bike with a 3:1 ratio to achieve the same feel. Our calculator assumes a standard progressive linkage found on most modern sport and naked bikes.
3. The Role of Sag
Once you have installed the spring recommended by the Ohlins spring rate calculator, you must set your sag. Static sag (the bike's weight alone) and Rider sag (bike + rider) are the ultimate indicators of whether your spring rate is correct. If you have to add too much preload to get the right rider sag, your spring is too soft.
How to Use the Results
If the calculator suggests a 92 N/mm rate, but Ohlins only offers 90 N/mm or 95 N/mm for your specific shock model, choose based on your primary use. Street riders seeking comfort should lean toward the 90 N/mm, while track enthusiasts should opt for the 95 N/mm to handle the high G-forces of heavy braking and cornering.