Any course, intervals/rest ratio. Hills, flats, small or large ring, group or solo ride, or road, mountain bike, or trainer/rollers. This is your day to simply put in the time, enjoy it, and go by your instinct/feel. Use HRM or don't, this is a creative ride.
Run 20' on a flat course or treadmill. Keep HR in Zone 1-2. Think about form and running with relaxed arms, face, neck, shoulders, and hands with high knees. Stretch when done and add in Core 1, 2 or 3.