He was one of the top riders in the Motocross Grand Prix World Championships during the late 1960s and early 1970s. In 1968 he was part of the Swedish team that won the Trophée des Nations. He was the F.I.M.500cc Motocross World Champion in 1969 and 1970 while riding for the Husqvarna factory racing team. Åberg was a member of three victorious Swedish teams at the Motocross des Nations in 1970, 1971 and 1974. In 1975 and 1976, he rode for the Bultaco factory in the 500cc class. He was also involved in production of new bikes, specifically the Yamaha XT500.