The 2019 Tour de France has just begun. As 190 riders speed through the streets of France, spectators will marvel at the tightly-packed formation of cyclists known as the peloton. Fans will argue that a peloton creates an aerodynamic advantage, allowing riders to conserve energy throughout the grueling three-week race.
source https://www.lifetechnology.com/blogs/life-technology-news-blog/tour-de-france-pelotons-governed-by-sight-not-aerodynamics