Virtual Races work just fine on treadmills - we can use your device's accelerometer to track paces and to initiate zombie chases. However, given that you will not be moving in real space, we will be unable to show you a map of your run.
In order to use Racelink on a treadmill, all you need to do is tap the Tracking button and choose Step Counting tracking rather than GPS tracking. For iPhone users, this button will display "GPS" as default.
For the most accurate results, you should set your stride length. You can find out more about setting your stride length in the following article: