 The UCI had originally highlighted the problems in his biological data for the 2011 and 2012 seasons through a letter in June 2013, which Kreuziger had responded to in October 2013, even though the values did not get out of the biological passport range which determines what values the gained cyclist samples ought to have.The UCI subsequently followed this up in May 2014.This prevented Kreuziger from riding the Tour de France and Tour de Pologne.