TM-1 Web

Spoke 1 of 32
Start here — next to the valve hole
Mic off
—Hz
—kgf
LOOSERTIGHTER
Listens continuously and logs each pluck automatically. Rest a finger on the spoke it crosses to damp it, then keep moving the same direction around the wheel.

Wheel Map

Good Uneven Critical
Mean
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Min
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Max
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Spread
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Readings

SpokeHzTensionDev.
No readings logged yet

Wheel & Spoke Setup

Measure the exposed spoke, not the full length: from where it enters the nipple to the point it crosses its neighbor (or to the hub flange for radial spokes).
Rough starting points only — check your rim/spoke maker's spec if you have one. Leave blank and it'll use the average of your own logged spokes instead.
Advanced (mic tuning) — most people won't need this
Auto: the listen range is worked out from your spoke's gauge and length, so you don't have to guess a frequency window.

How this works

Pluck a spoke like a guitar string. The mic captures the "ping," the app finds its fundamental frequency, and converts it to tension using the standard vibrating-string formula:

T = 4·μ·L²·f²

μ = mass per unit length of the spoke · L = free (speaking) length · f = pluck frequency.

This is a ballpark estimate, not a lab instrument — same idea as a mechanical deflection meter, just with a mic instead of a spring. Don't treat the absolute kgf number as gospel. What it's genuinely good at is telling you which spokes are way off from the others — the relative pattern across your wheel is much more trustworthy than any single exact reading, because errors in your spoke's mass/length estimate shift every spoke's number by roughly the same amount.

Two things that matter more than anything else for accuracy: hold the phone mic close to the spoke, and rest a finger on the neighboring spoke it crosses so it doesn't ring along and confuse the reading. Free length also has to be measured carefully — see the hint under that field in Settings.

Start here — the spoke next to the valve hole is Spoke 1. Tap Start Microphone, then just start plucking your way around the wheel in one direction, spoke by spoke. It listens continuously and logs each clean pluck automatically — no button to tap per spoke. The big number at the top always tells you which spoke you're on and what to do with it. Misfire from background noise? Tap Undo last.

Once every spoke on the wheel has been measured once, it stops walking forward and instead always points you at whichever spoke is currently furthest off — tighten or loosen it, pluck it again, and it re-checks. Keep going until it tells you everything's even. Don't know your spoke's mass per length or a target tension? Settings has quick "Road/MTB ballpark" buttons and works out a sensible listening frequency automatically — you don't need to know any of the physics to get started.

The wheel map and the LOOSER/TIGHTER bar under the numbers update live and color each spoke by how far it deviates from your target (or the running average of whatever you've logged so far — the bar is dim/inactive until you've set a target or logged at least one spoke).

A rough guide: a quarter-turn on a nipple is a meaningful change in tension, but exactly how much varies by spoke and thread — always re-measure after each adjustment rather than counting turns. And remember tensioning shifts trueness too, so check the rim in a truing stand as you go, not just at the end.

Needs HTTPS (or localhost) — phones block microphone access on plain http.

Build 2026-07-31.7