As an amateur, Jan Pieterse won several smaller races. In 1963 he won the Tour of Austria . In 1964 he started at the Olympic Games in Tokyo and won the gold medal in the team time trial together with Evert Dolman , Gerben Karstens and Bart Zoet . In the individual road race , he was 42nd. Shortly before the Olympic Games, he had become Dutch champion in the team time trial and had thus won the only national title of his career. From 1965 to 1967 he was a professional, but without much success.
Up until the Olympic Games in 1956, the times of the best three or four drivers of a national team from the individual time trial or the road race were added to the team ranking in this competition. The mode was changed several times.