He may not have completed all eight previous involvements in cycling's biggest race, but said this year's 3460-kilometre beast is unprecedented in his experience.

In the third of his exclusive interviews with The Examiner, the Launceston 34-year-old said the time to be spent in mountains takes this year's race to new heights.

"I've spent so much time at altitude this year preparing for it," he said.

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"There is so much high altitude in this year's Tour that you have to and every team is doing it."

After a testing early climb up La Planche Des Belles Filles in the Vosges region, riders face an individual time trial and mountain-top finishes in the Pyrenees before the Alpine business end of the race.

The last three stages before the procession onto the Champs-Elysees in Paris will certainly determine the overall winner as riders traverse the Alps including the highest paved road in Europe.

"The Pyrenees are normally harder than the Alps but not so this year," Porte said.

"Those last three days in the Alps are going to be decisive. There are multiple climbs over 2000m which adds another element because the air is so much thinner up there and you never know how your body is going to respond to that.

"You could lose time in the Pyrenees or on the team time trial but that could be seconds. Those three last days could be minutes. They are brutally tough.

"I cannot remember a Tour when the last three days are so tough.

"But by that stage everyone will have done 3500km so no-one will be feeling fresh.

"It will come down to who is healthy, mentally strong and wants it most."

Porte, who will spearhead Trek-Segafredo's assault on the race, said all teams with general classification ambitions have been extensively preparing at altitude.

He has completed training camps in Sierra Nevada, southern Spain, Park City, Utah, and most recently in the French Alps and said a downside to the acclimatisation is the impact it has on riders' ability to sleep.

However, as a specialist climber, Porte is excited by this year's Tour course.

"I'm generally pretty happy with it," he said. "It suits me more than the past couple of years.

"There's some hard climbs early on. The first really hard stage is La Planche Des Belles Filles. That's going to be decisive because normally early in the Tour that's where the riders that are going to go on and dominate make their move.

"When (Vincenzo) Nibali won (in 2014) that was where he first made his move and Froomey (Chris Froome) too."

After a couple of days with his wife, Gemma, and baby son, Luca, in Monaco, Porte heads to Brussels where the race begins.

"We'll do some team time trial training, relax as much as possible and then from Saturday it's into the circus."

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