Workshop Tools

Spoke Length Calculator

Enter measurements below. All values in mm. Select presets or type manually.

Setup
Wheel type
Hub dimensions
Hub width (K) & flange-to-dropout (Ka, Kb)
K (total width) Ka Kb
Flange spoke hole PCD (D1)
D1
Left flange dia?
mm
Right flange dia?
mm
Spoke hole dia?
mm
Hub total width (K)?
mm
Left flange-to-dropout (Ka)?
mm
Right flange-to-dropout (Kb)?
mm
Rim & lacing
Effective rim diameter (ERD)
ERD Nipple seat to nipple seat through axle centre
Rim ERD?
mm
Holes
Lacing
Rim offset?
mm
Formula reference
Spoke length is calculated using the standard trigonometric formula:
L = √(R² + r² + d² − 2Rr·cos(720X/N)) − 1.2 Where R = ERD/2, r = flange radius, d = centre-to-flange, X = crossings, N = hole count. The −1.2mm accounts for nipple depth. Always round up to the nearest available spoke size.
Results
Left spoke (non-drive)
—mm
Right spoke (drive side)
—mm
Precision±0.01 mm
StatusOptimized
Spoke hole dia2.6 mm
Rim offset0.0 mm
Always round up to the nearest available spoke length — typically even 2 mm increments. Verify ERD from rim manufacturer data.
Admin Panel
Add rim and hub presets — they will appear in the dropdowns above.
Add new rim
Add new hub
Admin Access

Enter admin password to unlock.

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