At the Junior World Championship in 1998 in St. Moritz Pieper jumped with the team to first place. In the same year he became German youth champion in special jumping. In 1999 Pieper jumped in the Continental Cup for the first time . At the Continental Cup jumping in Obersdorf in 2002, he got his best individual result with 2nd place. On December 29, 2000 he made his debut in Obersdorf at the Four Hills Tournament, followed by 21 World Cup appearances. His best individual result was 12th place at the World Cup competition in Sapporo 2003. In 2003 he became German champion in Oberwiesenthal . After the end of his career in 2006, he worked as an assistant trainer for the German women's ski jumping team.
Germany
