After competing in the International Peace Race in 1959 cyclist Roger Thull then became the national amateur champion of Luxembourg in 1960. This performance earned Thull a place on the Olympic team, with whom he placed 51st in the individual road race in Roma later that year. After the Games he turned professional, riding in the 1961 edition of the Tour de France, but was forced to abandon the race on stage 12. One year later Thull finished second in the road race at the national championships, before winning back-to-back titles in 1963 and 1964. His younger brother Marcel competed in the road race at the 1976 Montréal Olympics.