MRP Spring Calculator


MRP Suspension - Mountain Bike Spring Rate Calculator

Total Riding Weight (pounds):

  • The rider's weight with riding gear (average 5lbs for riding gear weight)

Rear Weight Bias (percent):

  • The standard formula is based on a 60:40, Rear to Front weight distribution
  • Add 5% for a heavy rider (+200lbs.)
  • Subtract 5% for a light rider (150lbs-)
  • Add 2% for a recreational or beginner rider (more rearward bias)
  • Subtract 2% for a pro-level or highly experienced rider (less rearward bias)

Rear Wheel Travel & Shock Stroke: (inches or millimeters)

Shock Sag: (percentage of shock stroke)

  • The standard for downhill is 30% sag
  • The standard for extreme free-riding is 27% sag
  • The standard for all-mountain riding is 25%

Preload Adjuster: (number of turns) The standard formula ignores the effect of applying preload and tends to calculate too high a spring rate. Usually 1.0 is required to lock the spring to the shock body. Choose a preload value that will allow some plus or minus adjustment consistent with your required sag level and re-submit. A zero preload spring rate is found, then preload is applied to find an alternate spring rate taking into account the preload spring tension. Calculation is based on a linear progression.

End-Coil Effect: (percent) Closed/Ground compression springs have a typically lower spring rate in their initial deflection range. The suggested 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 number of turns of the preload adjuster.

Input Parameters:
inches or millimeters

Rider Weight with gear (pounds)

Weight Distribution at rear wheel (percent)

Rear Wheel Travel(in or mm)

Shock Stroke (in or mm)

Shock Sag (percent)

Preload Adjuster (turns)

End-Coil Effect (percent)

Output Parameters: Travel Setting Three

Leverage Ratio: travel divided by stroke

Zero Preload Spring Rate: lbs per in

Alternate Preload Spring Rate: lbs per in

Suggested Spring Rate: lbs per in

Suggested Spring Rate Preload Sag: percent

Calculated suggested spring rate

( based on target preload as entered above )

( sag value is calculated from optional spring rate )

( never exceed spring preload limit - if unknown, never use more than 2.0 turns )

( more than 4.0 turns is not recommended )


Travel Setting One

Travel Setting Two

Travel Setting Three

Travel:     Ratio: 

Travel:     Ratio: 

Travel:     Ratio: