Methodology

Every calculation on this site cites its source. Every assumption is disclosed. Where the science is genuinely contested, we show multiple methods side by side and let the user compare. This page exists to make that work auditable.

Sources we trust

In rough order of preference:

1. Peer-reviewed cycling science (especially on bike fit and tire performance).
2. International standards bodies: ISO, ETRTO, ASTM, JIS, GB.
3. Manufacturer engineering documents — when they're methodology, not marketing.
4. Long-standing reference works: Sheldon Brown, Park Tool's Repair Help, Lennard Zinn's books, and the tire-pressure work of Frank Berto.
5. Reputable performance labs: Silca Pro, Bicycle Rolling Resistance, and similar.

We don't cite forum posts, Reddit threads, or YouTube videos unless those themselves cite primary sources we can verify.

Precision

Outputs report numbers to the precision that the inputs and the underlying methodology support — and no more. A tire-pressure calculator whose inputs are ±2 kg in rider weight should not report pressure to the nearest 0.01 psi. Where a tool's accuracy varies, the methodology section of that tool says so.

Per-tool methodology

Each tool ships with its own methodology page documenting its formulas, citations, and a worked example that the test suite verifies. The links populate here as tools go live.

• Gear Ratio Calculator — not yet shipped
• Tire Pressure Calculator — not yet shipped
• Frame Geometry Comparator — not yet shipped
• Tire & Rim Compatibility — not yet shipped
• Chainline & Q-factor Calculator — not yet shipped
• Fit Finder — not yet shipped
• Fit Translator — not yet shipped

Corrections

If you spot a methodology error, please open a methodology correction issue with the current formula, the proposed correction, and at least one primary source. Methodology corrections are merged on their merit and credited in the changelog.