A spoke length calculator for bicycle wheels.
I was always a bit unsure about the calculated spoke length of the freely available spoke calculators from, for example, Sapim or DT Swiss. The problem is that there are not many stores where you can buy spokes in one millimeter increments. Most stores only offer two millimeter increments. That’s why it is important for me to calculate the minimum and maximum spoke length so that I can order the correct spoke length. Since I use my own spoke length calculator, I never failed.
You need the basic dimensions of the hub and the rim and an idea about the spoke pattern.
(in-package :spoke-calculator-user)
(calculate
:hub (make-instance 'hub :pitch-circle-diameter (cons 56.0 54.0)
:pitch-circle-distance (cons 32.0 21.0)
:spoke-hole-diameter 2.5)
:rim (make-instance 'rim :base-diameter 536.0)
:spoke sapim-race
:spoke-count 32
:spoke-crossings 3)
(report *data* :output (user-homedir-pathname) :format :html)Open the generated report:
$ xdg-open ~/spoke-calculator.html
You should see something like that:
Steel spokes are made of spring wire. See, e.g. ISO 6931-1 “Stainless steels for springs – Part 1: Wire”.
| Name | Number | Condition | Young’s Modulus |
|---|---|---|---|
| X10CrNi18-8 | 4310-301-00-I | cold drawn | 180000 MPa |
| X10CrNi18-8 | 4310-301-00-I | stress relieved | 185000 MPa |
| X10CrNi18-8 | 4310-301-00-I | 196000 MPa | |
| X9CrNi18-9 | 4325-302-00-E | 193000 MPa |
| Standard Wire Gauge | 15G | 14G | 13G |
| Wire Diameter / mm | 1.8 | 2.0 | 2.3 |
| Thread Pitch / 1/in | 56 | 56 | 56 |
| DIN 79012 | FG2 | FG2.3 | FG2.6 |