Like his older friend Erling Evensen, Reidar Nyborg was from Mesnali in the municipality of Ringsaker north of Hamar, and both were members of the bronze winning Norwegian cross-country relay team at St. Moritz in 1948. Nyborg had his breakthrough in 1946, when he placed eighth in the 18 km at both the National Championships and Holmenkollen. In 1947 he placed seventh at Holmenkollen, his best ever finish at this famous ski event. In the 1948 Olympic season he was seventh in the 18 km at the Norwegian Championships, and he skied well in the selection races and earned a place on the Olympic team. In 1949 he had a great year, winning the 30 km race and placing third at 50 km at the National Championships in Steinkjer, after which he retired. Reidar Nyborg worked as a lumberjack, and died in his home in Ringsaker in 1990.