Most string changes move the ball less than the uncertainty on them.
This measures the change, states the uncertainty, and tells you when the two overlap — including when the answer is that you would not feel it.
The whole validated pull range, 29 to 81 lb, is worth 1.24 mph. That is 1.37%. The uncertainty on it is 3.66 times wider than the whole range.
Going one gauge thinner, 1.25 to 1.20 mm, moves stiffness where the ball meets the bed by 2.36%, against a band of 4.00%. Below what you could feel — if the band is right.
What it does
Measure your frame: three tape measurements of the strung area, the frame's length, its balance point, its unstrung weight on a kitchen scale, and the string pattern. Tell it your string, gauge and tension, and what you want to change. It ranks the changes actually available to you, for a stated swing, on the same metric it reports, and marks every one that sits inside its own uncertainty. The order genuinely depends on the swing.
What it knows, and what it does not
- Exact
- The mass and balance maths. Twistweight and swingweight are the parallel-axis theorem applied to masses you declare at positions you measure — exact given those inputs, and lead you declare enters it exactly too. The string bed's own mass is modelled rather than weighed, so every total inherits that model. It tells you when your frame's own figures are estimated rather than measured, because an estimated base can be off by roughly a factor of two, and every published delta scales with it.
- A guess
- Every string-to-string comparison. The material table is provisional and nobody has measured it. If the table is wrong, those numbers move — and it is the largest of roughly two dozen provisional constants across the engine.
- Never done
- None of this physics has been checked against a real racket. It is internally consistent, cross-validated against independent published sources, and mutation-tested — though not everywhere: the uncertainty machinery, the contact solver's derivation and the sampler were never systematically covered. That is a weaker claim than saying it is right, and the difference matters.
- The yardstick
- The uncertainty bands are themselves modelling assumptions, and nobody has measured those either. Both figures above are read against them — the tension lever against one band, the gauge step against another — so the bands are doing the arguing. If you feel a difference this tool calls too small to feel, there is no way yet to tell whether you are wrong or the band is.
- Not built
- The thing you would actually use does not exist yet. The engine is built and tested. The interface to it is not.
Reserve early access
$15 USD
Refundable on request at any time before it ships, and refunded in full if it never ships. Your deposit reserves early access to something that is not built yet.
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