BFF Academy · EZ course Why the 'right' bike fit is a range, not a number
Static fit vs dynamic fit
A bike fit is either static (measured with your body at rest) or dynamic (measured while you're actually pedaling). The difference is what each one can see.
| Static fit | Dynamic fit | |
|---|---|---|
| What's measured | Your body at rest. | Your body in motion. |
| How | Inseam against a wall, a plumb line from the knee, ratios on a clipboard. | Reading your joint angles through the pedal stroke. |
| What you get | A single target number. | An assessment of how you actually move. |
| Classic example | The LeMond formula: saddle height = inseam × 0.883. | A trained fitter watching you ride or motion-capture in a fit studio. |
None of that is wrong, it's just incomplete. A number from your inseam can't see how your foot drops or your hip rocks once you're moving. A dynamic fit can. The catch has always been cost, a dynamic fit historically meant a trained fitter, studio hardware, and a per-session fee.
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