Sjaak Pieters was a specialist for short-term events on the track, and there in special tandem race. In this discipline, he was 1977-1987 Dutch champion six times, three times with sound Vrolijk, twice with Lau Veldt and once with From Harren. He also won the 1978 national title in the 1000 -meter time trial. Twice - in 1978 ( with Veldt ) and 1982 ( with Vrolijk ) - he was on the tandem third at UCI Track World Championships. In 1976 he started in the Olympic Games in Montreal in the sprint, but retired in the second round of.
Pieters comes from a family of athletes: His wife is the two-time Olympic athlete and gymnast Ans Dekkers, his brother Peter Pieters was also racing cyclist.
Pieters 2011 was head of the Dutch cycling team Rucanor Line Cycling.