After that Sinnerud skated for 15 years in North America, winning six U.S. and Canadian titles in total.

Disappointed, Sinnerud returned to the U.S. and skated there professionally for several years, winning nothing, but placing within the podium in several races.

Although Sinnerud was Norwegian he was often referred to in American newspapers by the nickname "The Terrible Swede" because of his speed and the Swedish–Norwegian Union.

His trainees included Jan Langedijk, Klaas Schenk, Kees Broekman, Michael Staksrud, Reidar Liaklev and Hans Engnestangen.

His grandson Sven Peter Sinnerud became a technician at the Vikingskipet, preparing ice for all championships conducted there since 1994.