Australia's time-triallists proved no match for defending champion Fabian Cancellara at the road cycling world championships on Thursday.

The Swiss rider, who wore the leader's yellow jersey for the first week of this year's Tour de France, covered the hilly 44.9-kilometre course over the streets of Stuttgart, Germany, in 55 minutes, 44 seconds to retain the title he won last year in Graz, Austria.

Laszlo Bodrogi of Hungary was 52 seconds behind in second place and Stef Clement of the Netherlands was third, 58 seconds back.

Ben Day, who set off in challenging, wet conditions, was Australia's best-placed finisher in 29th among the 69-man field with a time of 59:27.17.

Cameron Wurf, the 24-year-old Tasmanian who only switched to cycling after finishing fourth in the lightweight coxless pair at the world rowing championships in September last year, was 31st in 59:30.21.

Adam Hansen, who was competing on his first national team, finished in an encouraging 38th place with a time of 59.52.20.

Friday is a rest day before the championships continue on Saturday with the women's road race, followed by the men's Under-23 version.

The elite men's road race will close the world titles on Sunday.

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