Carbon Drive Belt Tension Tool

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.

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.

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.