Australia's BMX Olympian Caroline Buchanan is poised to claim the overall World Cup title in the fourth and last round in Canada at the weekend.

Following a disappointing fifth place at the London Olympics, the 21-year-old from Canberra won the time trial in the Canadian round on Friday, her sixth straight time trial win.

The solo time trial rides determine the starting places for the racing on Saturday.

Buchanan, the current time trial world champion, leads the overall world cup points and is hoping to claim the overall series with her race results.

Fellow Australian Sam Willoughby, the men's silver medallist in London, won the men's time trial and is in a tussle for overall series honours with American rider, Connor Fields.