Career
Jahr was the skip of the German team at the 1984 World Junior Curling Championships, where he led the team to a 7th place finish. After juniors, he was picked up by the Rodger Gustaf Schmidt rink to play second for him. The team represented Germany at the 1990 European Curling Championship as well, but placed tenth.
Jahr would later leave the Schmidt rink to form his own team
He skipped the German rink to a 9th place at the 1996 Ford World Men"s Curling Championship and a 7th place finish at the 2011 European Curling Championships. He skipped Germany at the 2012 World Men"s Curling Championship to an 11th place finish.
Jahr then led Germany to an 11th place finish at the 2013 European Curling Championships. Germany"s poor performances in recent World Championships failed to automatically qualify the nation for the 2014 Winter Olympics.
At the Games, Jahr led Germany to a 10th place finish, with a 1–8 record.
Jahr announced his retirement from international curling at the conclusion of the round robin at the World Championship.