How fast is your treadmill belt actually moving? That question is the starting point for TreadSpeed. We are developing an iPhone app that lets you investigate belt speed using your phone’s camera.

From a marker to a speed reading

The method uses a small marker on the belt and the known circumference of the entire belt loop. The camera detects the marker as it passes, and the app calculates speed from the time between passes. You can then compare the result with the treadmill display.

The beta includes measurement with a known belt circumference, saved treadmills and a workout feature. Workout speed and distance are calculated from saved measurements and the speed changes you enter. The belt is not measured continuously while you exercise.

What we want to learn from the beta

The website and registration form are open. We are looking for experience across different iPhone models and treadmills, starting with a small group of 5–8 participants before expanding. Selected testers will receive an invitation and guidance by email, with installation through TestFlight.

  • Is it easy to find the correct belt circumference and position the phone?
  • Does measurement work in different lighting conditions and on different treadmills?
  • Are the results understandable and useful in practice?
  • Where do testers get stuck, and what should we improve first?

The main test consists of three measurements at each setting of 6, 10 and 14 km/h, at 0 percent incline and with no runner on the belt. Testers report both results and their experience. Trying the workout feature is optional.

Accuracy needs to be verified

Our target is a maximum deviation of ±0.5 percent from actual belt speed with the correct setup. This is a development target that must be checked against an independent reference. Repeated, consistent readings are useful, but they do not establish absolute accuracy on their own.

What happens next?

We will use feedback to improve setup, measurement and the way results are explained. This development journal will share what we learn and the milestones we reach. We will announce a launch date when we are ready to commit to it.

Do you have an iPhone running iOS 17 or later and access to a treadmill you have permission to mark? You can register your interest. Beta testing is free. Selected participants who take part as testers will receive free access to the app at launch.