How We Verify Our Calculators

A cycling calculator is only as good as the numbers behind it. A wrong rim reference width, a misremembered gear formula or an out-of-date training model gives you a bad fit, a bad order or a bad plan. This page explains the process we use to check every figure on this site against its original source.

The process

✓Every figure is traced to a named source category: ISO and ETRTO tyre and rim standards (such as ISO 5775 sizing and the 622, 584, 559 and 406 bead seat diameters), component manufacturer data from Shimano, SRAM, Campagnolo, Continental and Schwalbe, published training science such as the Coggan power zone and TSS models, established bike-fit methods (Hamley, LeMond, Holmes), and guidance from British Cycling, Cycling UK and the UCI.
✓Every calculator is tested against hand-worked examples: we derive the expected answer on paper from the underlying formula or standard, then confirm the calculator returns it.
✓Results are adversarially re-checked in independent audit passes that re-derive each figure from scratch rather than trusting what is already in the code. When a check disagrees with the code, we fix the code.
✓An automated test suite runs the worked examples on every calculator across desktop and mobile browsers before each deployment, so any change that breaks a checked result is caught before it goes live.
✓Errors reported through the feedback buttons on each calculator are investigated against the source, fixed and re-verified.
✓Content is reviewed when sources change, for example when a manufacturer revises component specifications or a training model is updated.

Verified, not guaranteed

These calculators give estimates and starting points, not professional advice. Fit numbers are a baseline to fine-tune on the bike, and for persistent pain or a dialled position see a qualified bike fitter or physiotherapist; for component compatibility and safety-critical work such as brakes and wheels, confirm with the manufacturer’s specifications or a qualified mechanic. Nutrition and training figures are general guidance, so check significant changes with a coach, registered dietitian or your GP.

Spotted an error?

Every calculator page has feedback buttons. If a figure looks wrong, tell us what you entered and what you expected: we investigate against the original source, fix anything that fails the check, and re-verify before the correction goes live. When a report shows a genuine error, the fix lands on the affected page itself, with a dated correction note where it matters.