Hansen was born in 1908, to Lars Christian and Rasmine and was one of three brothers who all went into dirt-track racing (later motorcycle speedway). He won the Danish Individual Speedway Championship (500cc special class) in 1937 and 1938, having previously won Danish Championships in other classes.[3][4]
He followed his older brother Morian Hansen into the British speedway leagues in 1936.[5] West Ham Hammers attempted to sign him in May 1936, but the Speedway Control Board blocked the transfer.[6]
However, later that year, he and another brother Kaj Hansen, also known as Kalle, were due to travel to London to compete in the inaugural 1936 World Championship.[7] Baltzer impressed in the qualifying round and progressed to the Championship round.[8]
To the annoyance of the other British teams (especially West Ham) the Hackney Wick Wolves were given permission to sign him in June 1936, because of their injury problems.[9] The transfer started a season long campaign by clubs to ban overseas riders and West Ham unsuccessfully applied to the Control Board to recall Baltzer's brother Morian (who was still on their retained list). Meanwhile, Baltzer and Morian helped Hackney win the 1936 London Cup.[10]
In 1937, he returned to Denmark to race, following an initial ban on overseas riders and did not return to race in Britain,[11][12] despite attempts by Hackney to bring him into the team again that season.[13]