Quick start:
Enable microphone access to the app. Settings->Privacy->Permission manager->Microphone->Spoke Tensioner->Allow only while using the app
Select the type of spoke on your wheel. If your spoke is not listed, select the one that is closest in size.
Enter the length from the nipple to the first point where the spoke crosses (touches) another spoke, or meets the hub.
Find a quiet location and gently pluck a spoke to get a tension reading. Rest your finger on the crossed spoke (the one NOT under test) to prevent it from interfering with the measurement. Slide the sensitivity slider to the left to lower the threshold to detect the tension.
Notes for new wheel builders:
This is one of several tools needed to true or build a wheel. A wheel truing stand is helpful, but leaving the wheel in the bicycle and using cardboard guides can work in a pinch.
A spoke wrench is necessary to tighten (and sometimes loosen) the nipples. Individual wrenches are preferable to a single wrench with multiple slots for the different size nipples which can be
cumbersome.
A dish tool (to get the rim centered on the hub) is also useful, but you can do without. To simulate a dish tool, start by removing the quick release, then mark two points on the rim directly across
from each other. You should be able to line up the marks and the center of the hub. Finally, place the wheel on a flat surface, pressing one of the marks down to the ground. Now measure from the surface up to the other mark. Flip the wheel and repeat the measurement. If the rim is centered, the measurements should be identical.
The instructions on lacing and fully building a wheel are available from books and websites. Once the wheel is laced and up to at least 50kg tension, you can start using this tool. Alternate between tensioning, truing, and roundness using at first, ½ turns, then ¼ turns to get things close to in shape. Check the dish. It can be corrected by doing a full round of loosening one side by ½ turn and tightening the alternate side by ½ turn.
To remove a wobble or hop, alternate between tightening one side and loosening the other side in small increments. Never exceed the manufacturer’s threshold for tension on the rim. Alternate between truing the drive side and non-drive side to keep the rim dished.
Detailed description:
This app exploits a fundamental physics rule. Increasing the tension of a string increases the frequency, increasing the mass of the string decreases the frequency, and finally increasing the
span decreases the frequency. These are the same fundamentals that guitars, pianos and any stringed
instrument work with.
The formula is F = 4f^2LM where M is the mass, L is the length and f is the frequency and the force F in newtons is the result.
There are issues with harmonics, and with other elements of the wheel vibrating. For this reason you must damp any other vibrations if possible. The one element that tends to be the most interfering is the crossed spoke (on a crossed wheel). Simply placing a finger gently on that spoke will solve the problem.
The app also deals with the 2nd, 3rd, and N-th harmonics by applying a band-pass filter. This filter is adjusted to match the expected frequency range for 50kgf to 150kgf. It changes based on the parameters input. This is one of the reasons a guitar tuner or other basic FFT tool will not be able to pick out the right frequency as well.
If you have problems, comments or questions, please send a message via the app website. Mega Mouse