Kate Mactier had been competing as a track cyclist for about eighteen months when she won a silver medal, behind the indomitable Sarah Ulmer of New Zealand, in the 3000 metres individual pursuit at Athens 2004. Mactier had been second in the event at the previous two world championships, in 2003 behind Leontien van Moorsel (nee Zijlaard), of Holland, and in 2004 behind Ulmer. In the ride-off for the gold medal both Ulmer and Matier shattered the previous world record, the third time Mactier had set a personal best time during the competition.
After Athens, Mactier became the world champion in the event in 2005 and won the bronze medal at the next three world championships. At Beijing 2008, she qualified seventh fastest but was beaten in the quarter-final by the eventual gold medallist, Rebecca Romero of Great Britain. Romero had won a silver medal in the women’s quadruple sculls at Athens.