Jun 19, 2026 · updated Jul 6, 2026 · Ger
A free, open Freespoke alternative: every wheel tool in one
Freespoke (kstoerz.com/freespoke), built by Karl Stoerzinger, is the calculator most of us learned on, and it’s what inspired this project. But this site didn’t start out as a Freespoke alternative only. It started because building a wheel today means hopping between tools, some free, some paid, and none of them does the whole job.
One wheel, five tabs
Think about your last build. You worked out the spoke length in Freespoke, in your spoke maker’s calculator or in a spreadsheet older than your hub. Your tensiometer’s conversion table lived in a PDF, or in an app that only knows one device. The hub geometry ended up being dug out of forum threads because the maker doesn’t publish it anywhere sensible. And your build notes, if you took any, landed wherever.
Here all of that lives in one place: you calculate the length, convert tensiometer readings, balance the wheel and save the build without switching tabs. In the browser, free, no login. The formula stays on screen, so when a number looks off you can see where it came from.
What it does
- Spoke length: exact 3D trigonometry, with left and right computed separately for dished wheels. It takes asymmetric rims (offset spoke bed) and straight-pull hubs, which plenty of free tools simply don’t handle. The formula and the intermediate values stay on screen.
- Multi-tensiometer tension: converts readings to tension on Park TM-1, DT Swiss Tensio 2, Unior, Super B, Wheel Fanatyk, Hozan and more. You pick the spoke by brand and model, then balance the wheel with a live radar, per-spoke status, dish guidance and a quarter-turn tuning plan.
- Truing simulator: practice without wrecking anything. Turn nipples and watch the tension spill over to the neighbours, and watch the dish, wobble and hop react. It’s a model for learning, not build advice.
- Save and share: name the build and copy a link. The whole wheel travels in the URL, no account.
The database
Over 1,200 hubs and 1,000 rims, taken from each maker’s official specifications wherever they exist and hand-checked before going live. Every record keeps its source and a confidence score. Anything without an official source yet is flagged for review, not hidden. The data is open: use it, check it, and if you spot an error, tell me.
How it compares
| Spoke Calculator | Freespoke | Maker calculators | Park Tool app | |
|---|---|---|---|---|
| Spoke length | exact 3D trig, per side | yes | yes | no |
| Asymmetric rims (OSB) | any rim | no | their own rims | — |
| Straight-pull hubs | per-side offsets | no | their own hubs | — |
| Tension conversion | Park, DT, Unior and more | no | no | TM-1 only |
| Truing simulator | yes | no | no | no |
| Hub/rim database | open, hand-validated, sourced | community-fed | own catalog | — |
| Math shown | with intermediate values | no | no | no |
| Price and login | free, none | free, none | free | free |
In short:
- Freespoke does spoke length very well. This adds the rest: tension, a simulator, asymmetric rims, straight-pull and a hand-validated database.
- Maker calculators (DT Swiss, Sapim…) work fine with their own catalog, but the job ends when the number comes out.
- Park Tool’s app converts tension for the TM-1 only. Here many more devices work, and the length and dish live in the same tab.
- Paid or closed tools charge money or an account for things that are free and auditable here.
Tension figures are estimates: devices drift and rims differ, so re-measure as you build and don’t push a conversion table past its range. Start with the length calculator and tell me what’s missing. New to this? There’s the glossary and the guide build a wheel from start to finish.