Spoke Tension by Ear

Pluck a spoke, and SpokeTune reads the tone through your iPhone's microphone and maps your wheel's tension balance onto a wheel-shaped radar chart — so you can see, at a glance, which single spoke is loose.

A physical spoke tensiometer often costs well over $100 — hard to justify if you only touch your wheels a few times a year. SpokeTune takes the old wrench-mechanic's trick — pluck a spoke and judge its tension by pitch — and makes it numeric, using your iPhone's mic and FFT pitch analysis. No special tool required.

WHAT IT DOES
- Pluck each spoke once; the app detects its pitch (frequency) and draws it onto a wheel-shaped radar, one spoke at a time — the circle "grows" as you go around.
- Finish the lap and loose or over-tight spokes stand out instantly. A well-built wheel forms a clean circle; an uneven spot dents inward.
- Spokes are auto-grouped by side, and each is compared to its own side's average as a deviation (%). Works for both front and rear wheels — including today's asymmetric disc-brake fronts.
- A 0–100 balance score plus a count of the spokes that need attention.
- Measuring is always free and unlimited. Tighten the loose spoke, measure again, and watch the dent return to neutral — that repeat loop is what the app is for.

HOW TO USE (3 STEPS)
1. Pick your spoke count (16–40) and front or rear.
2. Rest the iPhone near the wheel and, starting from the spoke next to the valve hole, pluck clockwise, one spoke at a time. Each pluck is detected and locked automatically, then advances to the next.
3. After one full lap, the radar and score show where the tension is uneven. Tighten the loose spoke and measure again.

FREE VS PRO
Everything you need to FIND the problem is free and unlimited: measuring any wheel, the radar, automatic side-grouping, deviation %, the balance score, and the needs-attention summary.

A one-time Pro upgrade (a single purchase, not a subscription) adds:
- Correction guidance — which way to turn each spoke (tighten or loosen) and by roughly how much, in fraction-of-a-turn steps (e.g. small ≈ 1/4 turn). Turn amounts are guidance, so always re-measure after adjusting.
- Estimated tension in kgf — enter spoke length, gauge, and lacing pattern, and the app converts each spoke's pitch into an estimated tension figure.
- Side-balance reference values for asymmetric wheels.
- Saved history, multiple wheel profiles, and measurement export.

HONEST LIMITATIONS
- SpokeTune measures tension balance. It does not measure rim runout (lateral or radial true) and is not a substitute for a truing stand — use it to even out tension before or between truing work.
- Pro's kgf figures are estimates derived from pitch and the specs you enter, not readings from a calibrated instrument. What you can rely on is the relative deviation within the same wheel and side.
- A spoke too loose to ring clearly gets flagged "needs review" instead of being given a made-up number.
- Over-tightening can damage rims and spokes. Tighten a little at a time and re-measure often.

WHO IT'S FOR
- Road, gravel, commuter, and MTB riders who do their own touch-ups and want to catch a loosening spoke early.
- Anyone who can't justify a dedicated tensiometer but wants to know where their wheel's tension sits.
- Wheelbuilders who want a quick acoustic cross-check of a fresh build.

Everything runs entirely on your iPhone. No recordings are stored or transmitted, and the app never connects to the network.