Calculator
Spoke length
Left
292mm
293.4 mm worked out
Right
292mm
292.1 mm worked out
Working
How it is worked out
Length = √(a² + r² + R² − 2rR·cos θ) − hole ÷ 2
- a is the distance from the hub centre to the flange, measured along the axle.
- r is half the flange diameter, measured hole centre to hole centre.
- R is half the rim ERD, the diameter where the nipple ends sit.
- θ = 720° × cross ÷ spokes. Above 90° the spoke would lie across the flange.
- Stocked lengths come in 2 mm steps. We round down, because a nipple takes up 1 mm of thread better than it bottoms out.
The default numbers are a 700C rear wheel on a road hub. Measure your own rim ERD: rim makers’ figures are often 1–2 mm out.
