Carbon Drive Belt Tension Tool

Carbon Drive Belt Tension Tool

Gates Carbon Drive

20 ratings
40 reviews
Free

Details

  • Released
  • Updated
  • May 25, 2011
  • September 18, 2025

Features

Carbon Drive Belt Tension Tool screenshot #1 for iPhone
Carbon Drive Belt Tension Tool screenshot #2 for iPhone
Carbon Drive Belt Tension Tool screenshot #3 for iPhone
Carbon Drive Belt Tension Tool screenshot #4 for iPhone
iphone
ipad
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About

This app uses your phone's microphone to measure the sonic vibration frequency of a belt drive. It helps you determine if your bicycle belt tension needs adjustment by comparing the frequency to a provided chart. It also offers a calculator for bicycle belt drive parameters like speed ratio and center distance.

Sonic belt tension measurement
Vibration frequency reading
Belt tension adjustment guide
Speed ratio calculation
Center distance calculation
Belt length and sprocket size adjustment
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What's New in Carbon Drive Belt Tension Tool

2.7.11

September 18, 2025

Bug Fixes

User reviews

Mic simply doesn’t work. Very inaccurate.

Perfectly silent room, completely usable iPhone 15 Pro, readings are all over the place. Strum it 10 times, I’ll get 4 readings from 20-28 hz, a few readings around 40-50 hz, and the rest above 75 hz. There is no way I could trust taking any of these as an indicator or whether I need to go looser or tighter on my belt. Luckily I have the Gates Krikit gauge. I can click that thing 50 times and get 36 lbs every single time. I was more or less just hoping this app would be a useful reference out and about if I’m without the Krikit.

I give the app a couple stars for the calculator and suggested tension chart. But the microphone tool is no bueno and almost more of a liability in my mind. I’d be worried that someone is going to take their readings and go too loose and end up shredding their belt or worse they go too tight and cause the bearings on an IGH to explode.
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Too sensitive, also doesn’t work anyway

First of all, I don’t do bike maintenance in an anechoic chamber. But even when I did get it as close to silent as possible in the real world (inside, heater off, no people or pets in the house, no moving my body except to pluck to belt, no breathing while the mic is on), I never could get four similar measurements with the crank in the same position (which seems like a prerequisite for trying it with the crank in different positions). A typical set of four would read something like 52 Hz, 98 Hz, 32 Hz, 87 Hz. Tried it on two different devices, so it’s not a mic issue. I give up.
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Pretty much pointless.

4 plucks of the belt, 90hz,30hz,89hz and 45hz. Cant do anything with that data.

Could be better

I wanted to check my bike’s belt tension. This app is a noble attempt at making that easy, but it falls a bit short. First, you *really* need to be somewhere very quiet otherwise your readings will be drowned out. Second, the app seems to have trouble with harmonics. I’d often get readings of 25hz then 50hz then 25hz again. To be honest a spectrograph might be more helpful than a single number.
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Barely good enough

I have now used the app multiple times. I used it on my Priority 3 speed bicycle. I have gained some experience adjusting the belt and using the app. The app is very sensitive. Ignore the many false readings. I delete them so I know where I am. Things have to be completely quiet. This is essential. You will still get false readings. That was the only part of the app I used. I would also recommend that the average tension reading be ignored. I had an odd sensation when pedaling in second gear when my average was within range but there was a spot that was tighter and out of range. That’s not an issue with the app but a helpful tip. I also recommend squeezing the belt when tightening the axle nuts. Only measure the tension with the app when they’re tight. The Priority website is helpful, if brief. Having the bike upside down on the floor is better than in a stand. Finally, plucking the belt makes your fingers sore quickly.
There are actual tools out there for measuring belt tension, but the app is free and good enough for doing it occasionally.
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Developer apps

FAQ

What does the Carbon Drive Belt Tension Tool app do?

This app measures the sonic vibration frequency of your belt drive using your phone's microphone. It helps you determine if your bicycle belt tension needs adjustment by comparing the frequency to a provided chart. It also includes a calculator for key bicycle belt drive parameters.

How do I measure belt tension with the app?

To measure belt tension, you simply pluck your belt like a guitar string. The app then uses your phone's microphone to read the vibration frequency. You can then compare this frequency to the included chart for bicycles or your vehicle's owner's manual for scooters/motorcycles.

Is this app free to use?

Yes, the application is available for free. There are no in-app purchases or advertisements mentioned, suggesting a completely free experience for users.

What bicycle drive parameters can I calculate with this app?

The app allows you to find key parameters of your bicycle belt drive, such as speed ratio and center distance. You can also change belt length or sprocket sizes to better suit your riding needs and compare different bike setups.

What devices is this app compatible with?

The app utilizes the microphone on your phone to read vibration frequencies. While specific operating system compatibility isn't detailed, it's designed to work on smartphones that have a functional microphone.