- Some ERG apps choose not to display your wheel speed, because wheel speed indoors doesn't correlate with your speed on the bike outdoors, and isn't a useful independent measure of your progress.
- Apps that are designed for outdoor use may only display GPS-based speed. In this case, since you are stationary, they should report a speed of 0. The 4iiii app only displays speed based on GPS. Extremely low GPS speeds may also be reported due to minor error in the GPS.
- If your app stops reporting speed and power, see I've stopped getting updated power, cadence, and/or speed readings in my app.