Enter your input parameters and click "Submit" to calculate your spring rate, or "Reset" to start over:
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- Total Riding Weight (pounds): includes the rider and anything else added to the bike; e.g., lock, water bottles, etc.
- Rear Weight Bias (percent): the standard formula is based on a 60:40, rear-to-front total weight distribution. A more accurate way would be to use
a bathroom scale under the rear wheel and a 2x4 under the front wheel, to determine the true sprung weight at the rear
wheel. Position your body according to your riding style, and then enter this value for your total weight. Note that the
default weight bias is sixty (60) %. Alternatively, you can use 55% for XCountry, 65% for Freeride, and 70% for Downhill.
- Rear Wheel Travel (inches)
- Shock Stroke (inches)
- Shock Sag (percentage of shock stroke): the standard formula uses the Fox Racing Shox-recommended 25% of shock stroke. A zero-preload spring rate is determined, then preload is applied to calculate the corresponding sag. Choose a sag appropriate to your riding style. If you are an extreme rider (jumps, drops, big hits, etc.) you should run less sag and a correspondingly higher spring rate.
- Preload Adjuster (number of turns): a minimum of 1.0 is required.
- End-Coil Effect (percent): closed/ground compression springs have a typically lower spring rate in their initial deflection range. The canned value is a best guess of the effect ECE will have on preload adjustment. It is a percentage of the overall spring rate used in calculating the spring tension for the specified turns of preload.
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Preload Precautionary
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| Preload adjusters apply about 1 mm or .039" per turn.
If the spring is not marked as to its real stroke, never use more than 2.0 turns on the preload adjuster, to avoid coil binding.
If the spring is marked as in 600# x 1.63" or 600# x 41 mm, calculate the available preload by spring stroke minus shock stroke.
Caution! Be careful! Although you may be well within limits for avoiding coil binding, using excessive preload will overly stress the shock,
leading to possible premature failure. |
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Correction For Suspension Progression
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Anything plus or minus (±) 7% can be ignored.
- Rising Rate (7% - 15%): subtract 50 lbs.
- Extreme Rising Rate - rare (15% - 25%): subtract 100 lbs.
- Falling Rate (7% - 15%): add 50 lbs.
- Extreme Falling Rate - common (15% - 25%): add 100 lbs.
Or, simply ride with the calculated spring rate and let personal preferences make your determination. |
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Correction For Stable Platform Shocks
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If you have already corrected for suspension
progression, try a 50 pound lighter spring, otherwise try a 100 pound lighter spring. Some suggest as much as 40% lighter,
but you risk the chance of blowing through your travel when the stable platform compression filter opens up.
Or, simply ride with the calculated spring rate and let personal preferences make your determination. |
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