Can I change riders during a workout?
Yes. There's a couple ways you can go about. It works best to have "No Rider" assigned to the empty seats when a workout begins. As people walk in the door they may then select their name on the correct rider display. That athlete then gets their own 10-second countdown to start the workout already in progress. When the workout is finished their total time is adjusted.
If a rider is already selected then the workout must be paused. A new rider may then be selected. Once you are ready then resume the workout.