I’ve been watching documentaries about people trying to break the land speed record for bicycles. There is an event where they can slipstream a powered vehicle.
The airflow (blue) passes around a vertical plate (green) on a vehicle and vortices then swirl around the back of the rider.
This greatly lessens the effort required.
Today’s invention is a large back shield (red) which acts as a sail which is intermittently hit by the vortices and thus provides even greater forward thrust on the rider.
This would work best when attached firmly to the bike itself.