Bicycle spoke length
Calculate left and right spoke lengths from rim ERD, flange geometry and crossing counts. Drag the graph handles to change inputs and explore the result.
Your inputs
The editable example is illustrative. Enter your own dimensions, operating data, prices, and fees. Results update as you edit.
Calculations run in your browser. Inputs are not saved or sent to analytics.
How it works
- = / 2; r_L = / 2; r_R = / 2
- θ = 4π × / ; l = √(( − )² + 2(1 − cos θ) + d²) − /2
Input and formula key
Your result
Complete the inputs to see your result.
Assumptions and limitations
Use measured nipple-seat ERD and flange hole-circle diameters, not outside flange diameters. Offsets are distances from the wheel center plane. This ideal J-bend model subtracts half the spoke-hole diameter; nipple engagement, stretch and purchase rounding need a wheelbuilder’s check. Example: ERD 600 mm, flange 60 mm, offset 35 mm, 32 spokes and 3 crossings give about 290.65 mm.
Sources
- DT Swiss — spoke calculator and required wheel measurements Sources reviewed: 2026-10-22
- Sapim — rim and hub measurements Sources reviewed: 2026-10-22
