Together with the Ulmer Raymond Dieter Hörmann was Wiedenmann already youth champion in double sculls. In the adult area, the two Ulmer formed with the two Ingelheimern Michael Dürsch and Albert Hedderichstraße the West German sculls. 1979 and 1982 the team was runner-up, each behind the boat from the GDR. 1983 won the West German occupation the world title in front of the GDR, this was the first defeat of the quartet from East Germany in the World Championships since the introduction of this class of boat in 1974.
Another high point of the career of Dieter Wiedenmann and his three colleagues was the victory in the quadruple sculls at the 1984 Olympic Games in Los Angeles.
Wiedenmann died at age 37 from internal bleeding during surgery to stabilize the spine.