Motorcycle suspension preload thread calculator

Calculate geometric adjuster travel and ideal force change per spring with your own figures.

Your numbers

Use the units shown. Results update as you change valid inputs.

Use geometric adjuster travel and ideal force change per spring to compare changes to your inputs. The method and limits below explain the scope.

Examples

Examples

Try the starting example

Supplied preload-adjuster thread pitch (mm/turn)
1.5
Signed adjustment turns
2
Supplied ideal linear spring rate (N/mm)
10
Identical springs affected
2
Initial modeled spring compression (mm)
5
Geometric adjuster travel (mm)
3
Ideal force change per spring (N)
30
Ideal total force change across supplied springs (N)
60
Ideal spring-energy change across supplied springs (J)
0.39

Try another scenario

Supplied preload-adjuster thread pitch (mm/turn)
1.5
Signed adjustment turns
-1
Supplied ideal linear spring rate (N/mm)
10
Identical springs affected
2
Initial modeled spring compression (mm)
5
Geometric adjuster travel (mm)
-1.5
Ideal force change per spring (N)
-15
Ideal total force change across supplied springs (N)
-30
Ideal spring-energy change across supplied springs (J)
-0.1275
Calculation method

Calculation method

Geometric adjuster travel (mm)

Pitch×signed turns, assuming direct axial transfer.

Ideal force change per spring (N)

Supplied linear spring rate×travel.

Ideal total force change across supplied springs (N)

Per-spring force change×identical spring count.

Ideal spring-energy change across supplied springs (J)

0.5×rate×travel×(2×initial compression+travel)×springs/1000; final modeled compression must remain nonnegative.

Symbols and units
a
Supplied preload-adjuster thread pitch (mm/turn)
b
Signed adjustment turns
c
Supplied ideal linear spring rate (N/mm)
d
Identical springs affected
e
Initial modeled spring compression (mm)

Use the units shown. A list keeps the order in which you enter its values. The symbol ^ means “raised to the power of”.

Assumptions & limits

Assumptions & limits

  • Direct axial geometry and an ideal supplied Hooke-law spring model, not a recommended preload, ride-height or suspension setting. Linkage, friction, nonlinearity, travel stops and suitability are external.
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Further reading

OpenStax: ideal Hooke-law force and elastic potential energy ↗

Background reading; this does not imply endorsement or independent review of SumFizz.

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