Wichmann found further success at the ICF Canoe Sprint World Championships, winning a total of 18 medals. This included nine golds (C-1 1000 m: 1979, C-1 10000 m: 1970, 1971, 1974, 1977, 1979, 1981, 1982; C-2 1000 m: 1971), four silvers (C-1 500: 1971, C-1 1000 m: 1966, 1978; C-2 1000 m: 1970), and five bronzes (C-1 1000 m: 1973, 1975; C-1 10000 m: 1973, 1983; C-2 1000 m: 1973).