walker took up bmx due to sibling rivalry; she wanted to be able to do what her younger brother could do, and do it better than him. in the 2008 season uci rounds, walker won seven races, came second in one race and didn't race two races. she was ranked number one in the world by the uci in 2008, and was one of the favourites to win the bmx women's event at the 2008 summer olympics in beijing, in the end she finished fourth. walker has won a total of twelve new zealand 20" titles from 1999 to 2011.