Final answer:
In a staggered riding formation, the third rider should maintain a two-second gap behind the leader for safety and sufficient reaction time.
Step-by-step explanation:
When riding in a staggered formation, the third rider in the group should ride two seconds behind the leader. This staggered riding formation helps maintain a safe riding distance between motorcycles, allowing each rider enough time to react to hazards and sudden stops. The leader rides on the left side of the lane, while the second rider stays on the right side of the same lane but a second behind, and the third rider should be two seconds behind the first rider on the left side of the lane again, creating a staggered pattern.