French amateur cyclist René Brossy was active throughout the 1920s and was first noticed with a second place finish at the national road race championships in 1925. The following year Brossy finished third in the Paris-Évreux one-day race and sixth in the road race at the World Championships. His breakout year was 1927, when he became the French road race champion, along with wins at the Paris-Reims and the Paris-Rouen one-day races. Brossy won the latter again in 1928 and was once again crowned the national champion in the road race to earn himself a place on the French Olympic team. At the Games he finished a disappointing 52nd in the individual road race, almost one hour behind the winning time, but redeemed himself on the track when he came fourth in the 4,000 metres team pursuit. One year later Brossy was once again the French amateur road race champion and finished third at the World Championships.