Build or true your wheels by sound. Easier and cheaper than handheld tools. Simply pluck a spoke and the tension is shown on the screen.

Save multiple wheels to iCloud and share them among your devices.

Get a visual of your wheel's tension with the 'Wheel Builder' view.

Support for many different spoke sizes, shapes, and materials.

Many mechanical tension gauges have low precision with steps of 10 kgf or more between readings. The app has much higher precision, down to 1 kgf.

What's New

Version 3.0

Added a visual display of tension
Updated the frequency detection algorithm
iCloud backup and sharing between devices
Improved memory performance

Ratings and Reviews



First, it does need to be a relatively quiet setting. Second, made truing my wheel very even with having spoke tension data. Third, I have an iPhone 7 which has great not sure how it works on a legacy device or iPad.

I might even start building wheels (again) with an app like this. This app is a home run!

A miserable failure


After truing my wheel on the Park Tool 2.2 wheel truing stand I wanted to insure I had uniform tension on the spokes. Lacking a spoke tension gauge I checked for an app and tried this one. While the concept made sense, when I was done my wheel was horribly out of true. And when I could hear clear differences in tone the app failed to detect them. Pretty disappointing.

Nice tool


For those of us who are tone deaf, nice tool to verify tension. I use it to verify evenness of tension. Have always built by feel (and never had a broken spoke, including on multiple sets of tandem wheels) and plucked to compare tensions, but I'm not the most accurate on tones.
Ignore the 1 star review - I was able to use all features fully within 2 minutes, instructions are fine. If you're able to lace a wheel and have read Jobst Brandt's book or other reputable reference, you should be able to understand this just fine. This does not replace a truing stand.
I do not own a tensiometer to physically verify readings. If developer stated clearly that the frequency to force calculations have been physically verified, I wouldn't put in that caveat. If I missed that, sorry, will pull that caveat. Readings are reproducible - measured same wheel multiple times, same force readings each time.
Wish list: report output (or xls file output)


Douglas Pepelko
6.7 MB
Requires iOS 8.0 or later. Compatible with iPhone, iPad, and iPod touch.
Age Rating
Rated 4+
© Douglas Pepelko


  • Family Sharing

    With Family Sharing set up, up to six family members can use this app.

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