Spoke Length Calculator

Calculate bicycle spoke length from rim ERD, hub flange diameter, center-to-flange offset, spoke count, and cross pattern

Frequently Asked Questions

What is ERD and why does it matter?

ERD is the effective rim diameter measured to where the spoke nipple seats, not the bare rim diameter. Using the wrong diameter is the most common spoke-length mistake, so always enter the ERD.

Why calculate the two wheel sides separately?

Most wheels are dished, so the left and right hub flanges sit at different distances from the center. Running the calculation once per side with each flange offset gives the correct length and even, reliable spoke tension.

Important Disclaimer: Estimates for informational purposes only.

This calculator provides estimates for informational purposes only. Results are based on assumptions and may not reflect actual outcomes. Consult qualified professionals in relevant fields before making important decisions based on these results.