I would love to see the ability to integrate heart rate into a custom workout. For example, for a zone 5 work, being able to hold 230 Watts for 10 seconds at a certain HR, then being able to trigger the workout to drop to zone 1 (i.e., 53 W) for a minute while your HR recovers, then repeat. It might be easier if it was rider initiated and merely hit a button to toggle to the next ‘wattage’ step.