Stage five: Vittel to La Planche des Belles Filles

The Tour opens with a time trial in Dusseldorf, before two sprint stages sandwich a hill-top finish in Longwy, where the yellow jersey could well change hands.

But the main GC contenders will face their first serious battle on stage five, on a 160km stage from Vittel to La Planche des Belles Filles.

Twice the climb has featured as a summit finish in the Tour, with Chris Froome and Vincenzo Nibali the two winners – giving a clue as to the calibre of rider who thrives on this climbs.

At 5.9km it’s far from the longest climb the riders will face, but boy is it steep – anybody struggling to find form in the opening week will be found out as it pitches up straight away to close to a one-in-ten gradient.

The steepest pitch, a nasty 14 per cent kick, features right at the top and will offer a first chance to examine the form of the GC contenders.

The first climb is brand new to the Tour, the second features pitches as steep as 22 per cent in parts and the third makes its return to the race for the first time since the 1970s; recons will be vital.

The gradients are consistently above one in ten on the three climbs, with Mont du Chat an 8.7km climb with an average gradient if 10.3 per cent.

The descent will be just as important as the ascent too – the climb tops out some 25km from the Chambery finish line. The following day’s rest day will be hard-earned.

Stage 12: Pau to Peyragudes

The sprinters could have another two opportunities after the first rest day, before the climbing action starts in the Pyrenees on stage 12.

Peyragudes is a new summit finish for the race, with the stage finishing on the runway of the Pyrenean airport, which should make for some spectacular scenery.

Stage 13: Saint-Girons to Foix

Chris Froome won last year’s Tour de France, but blew his chance of winning the Vuelta a Espana a month later on a short stage, packed with big climbs – characteristics shared by stage 13 of the 2017 Tour de France.

After the previous day’s epic to Peyragudes, the GC men will have to be on their guard on the tough, compact stage 13.

At the Vuelta, the 118.5km stage to Sallent de Gallego saw Nairo Quintana stretch his overall lead with a superb tactical ride, leaving Froome, isolated from his team-mates, unable to chase back on.

More than 90 riders finished the day outside the time cut, such was the brutal nature of the course and the attack, prompting the race jury to relax the rule that would otherwise have seen all of them leave the race.

Lessons should have been learned by the time of this 100km Tour de France stage, but with the Col de Latrape, Col d’Agnes and finally Mur de Peguere – whose slopes get as steep as 18 per cent gradient – there’s plenty of chance for a GC contender to make a big difference on what should be an intense day.

Stage 17: La Mure to Serre-Chevalier

The race’s mixed parcours means every second could count on the intermediate stages, with short, punchy climbs and potential for crosswinds again either side of the final rest day.

It’s stages like stage 17 where the biggest difference should be made, however, with a triumvirate of iconic Alpine climbs to tackle.

First up is the Col de la Croix de Fer, the 24km climb with an undulating gradient which makes it hard to tap out a rhythm.

And that’s followed by the fabled Col du Galibier – back on the menu for the first time since 2011 – via the Col du Telegraphe.

The Telegraphe is 11.9km with an average gradient of 7.1 per cent, while the twisting slopes of the Galibier cover 17.7km in all – the average gradient of 6.9 per cent hiding the fact it gets much tougher towards the summit.

It was scheduled for inclusion back in 2015 but had to be dropped from the race due to landslides – and the pure climbers will be itching to tackle its iconic slopes this time out, before an 18km descent to the Serre-Chevalier finish line.

Stage 20: Marseille, 23km ITT

One thing you don’t want before a potentially pivotal time trial is a long, hilly stage, but the Tour de France is not meant to be easy.

So after a 220km ride from Embrun to Salon-de-Provence, where the breakaway is likely to dictate proceedings, the penultimate stage of the 2017 Tour de France is a race of truth in the country’s second city.

However, at 23km long, it could have been much worse for the mountain goats – last year’s race featured a combined total of 54.5km of time trialling, as Chris Froome stretched his overall lead, whereas this year’s edition has 36km in total.

Stade Velodrome – now known for sponsorship purposes as the Orange Velodrome – hosts the start and finish of the stage, which takes place on largely flat terrain, bar a short climb to the cathedral.

But if the GC is still tight going into the penultimate stage, it will be yellow not Orange dominating the agenda.

Joaquim Rodriguez and Ryder Hesjedal may both be retiring this winter, but both will remember all too well how big a difference a 20-odd kilometre time trial can make. Rodriguez led the 2012 Giro d’Italia going into the final 28.2 km TT stage in Milan, but Hesjedal overhauled the Spaniard to claim the title.