Bicycle Spoke Length Calculator
Left and right wheel geometry
Calculate spoke lengths before ordering
Result
Calculation summary
Enter values to see the result
Live wheel-geometry preview
Dish changes each side independently
Left spokes
302 mm
Right spokes
300 mm
Total spokes
32
Separate flange distance, diameter and cross count produce separate purchase lengths for left and right.
How to use this calculator
- 1Measure the rim's actual ERD and the hub flange diameters and center-to-flange distances.
- 2Enter total spoke count, rim offset and left/right cross pattern.
- 3Review raw and rounded lengths, then confirm nipple and component-maker requirements before buying.
Formula
L = √(R²+r²+d²−2Rr cos(4πx/N))
Rim radius, flange radius, lateral distance and lacing angle are solved independently on each side.
Calculation steps
- Convert every geometry measurement to millimetres.
- Solve each spoke triangle and apply the selected hole correction.
- Round to available stock length and report geometric tension ratio.
Worked example
A 600 mm ERD, 58/45 mm flanges and 3-cross 32-spoke rear wheel can require slightly different left and right lengths.
Assumptions
- Spokes are evenly divided between two flanges.
- Holes are evenly spaced.
- The wheel uses conventional planar geometry.
- The entered correction matches the component system.
Sources
Frequently asked questions
What is ERD?
Effective rim diameter is the nipple-seat diameter used by the rim maker's spoke-length convention.
Why are left and right lengths different?
Dish and flange geometry change the spoke triangle on each side.
Should I round up or down?
Use the raw values with nipple engagement and the component maker's guidance; the tool shows stock rounding, not a universal rule.
Can I trust a database measurement?
Measure the actual parts whenever possible because model revisions and measurement conventions differ.