Two of Australia's top time trialists deliberately finished well down the table in the Tour de France's final race against the clock into Chorges.

Richie Porte (Sky) took it easy during Wednesday's's individual time trial (ITT) to save his legs ahead of three gruelling days in the Alps where he'll help teammate and race leader Chris Froome.

Meanwhile, former winner Cadel Evans (BMC) cruised over the 32km course hoping to slip further down the general classification (GC) so he might be allowed to chase a stage win before Paris.

Triple ITT world champion Michael Rogers was Australia's best performer on Wednesday's 17th stage.

He finished 13th just 2:25 back from winner Froome who averaged 37.24km/h.

Rogers' ride moved him up to 11th overall and put Saxo-Tinkoff into the lead in the team classification.

Porte declared on Tuesday he'd treat the time trial as "a rostered day off" and he did just that.

The 28-year-old, who came fourth in last week's flat ITT, was 57th on the stage almost five minutes down on his teammate.

Evans was 167th more than eight minutes in arrears.

"I went slower today to lose more time to be less of a threat to the GC contenders," Evans said after the hilly time trial.

He's now 18th overall some 24:24 down.

But the 36-year-old is still worried that, "going by past experience", other riders won't want him in any breakaway hunting a stage win in the Alps.

Evans also on Wednesday admitted coming third in the Giro d'Italia in May had taken more out of him than he'd first thought.

"It was something that we tried knowing there was a certain element of risk to riding the Giro and the Tour," he said.

"That was a decision we made back in March and obviously for the Tour it hasn't worked.

"A reasonable Giro and a very good Tour was the goal but there's not much I can do about that now."

There's no doubt about Froome's superiority in 2013 after the Kenyan-born Briton claimed his third stage win of the 100th edition of the Tour.

But Saxo-Tinkoff - with Alberto Contador second on GC and Roman Kreuziger third - has promised to test Froome's ability in the Alps.

"Tomorrow and the next days we will continue our plan and follow our objective which is to win Tour de France," director Fabrizio Guidi said on Wednesday.

The 18th stage features six climbs including two ascensions of the famed Alpe d'Huez.