After ending his career, Hamburger started a building company and a bike shop.

He was fired from Team CSC in 2001, after a positive EPO test.

Since then, the Danish Cycle Union refused to let Hamburger represent Denmark.

In his book Den største pris – en cykelrytters bekendelser (The Greatest Cost – Confession of a Cyclist) released in Denmark on 7 November 2007, he admitted to using EPO and human growth hormone from 1995 to 1997.

[1] His name was also on the list of doping tests published by the French Senate on 24 July 2013 that were collected during the 1998 Tour de France and found positive for EPO when retested in 2004.