PARIS -- With seven mountain stages and five summit finishes, including three above 2,000 metres, this year's Tour de France is the highest in the history of the race.
The route for the 106th edition of the thee-week marquee event offers only a few moments of respite. The first mountain test will come after just five days of racing, and contenders won't be able to hide their tactics for long.
Also, there is only 54 kilometres against the clock, split between one team time trial and an individual time trial, meaning a pure climber has a good chance to triumph in Paris on July 28.
Here is a look at five key stages that could define the race dynamics.
STAGE 6: Mulhouse to La Planche Des Belles Filles, 160.5 kilometres, July 11.
Introduced to the Tour in 2012, the Planche des Belles Filles ascent immediately became a classic.
Set up in the Vosges mountains, it is steep, tortuous and brutal, featuring a 20 per cent gradient at the top. Chris Froome, who is missing the Tour this year because of an injury, mastered the Planche in 2012 and Vincenzo Nibali triumphed at the summit in 2014, the year he won the Tour.
The final ascent comes after several other climbs including the Markstein, the Ballon d'Alsace and the Col des Chevreres, meaning the pack should be reduced to a small bunch of general classification contenders in the last few kilometres.
STAGE 13: Pau, individual time trial, 27.2 kilometres, July 19
The only individual time trial of this year's Tour is taking place on a rolling terrain and features an uphill stretch of road with a seven per cent gradient. A good chance for overall contenders to gain valuable time on the pure climbers before the race ventures into the high mountains.
The winner of the stage will receive a special collector's shirt marking the 100th anniversary of the yellow jersey.
STAGE 15: Limoux to Foix Prat d'Albis, 185 kilometres, July 21
Coming right after Stage 14 to the famed Col du Tourmalet -- the first of three finishes over 2,000 metres this year -- the last Pyrenean trek running close to the ancient Cathar castles is a grueling and daunting ride totalling more than 39 kilometres of climbing. The final ascent of the day leading to the finish at Prat d'Albis is an 11.8-kilometre climb at an average of 6.9 per cent. The Tour's "Queen Stage."
STAGE 19: Saint-Jean-De-Maurienne to Tignes, 126.5 kilometres, July 26
At 2,770 metres, the Iseran mountain in the Alps is a Tour de France giant, and one of the highest road passes in Europe where thin air makes things harder for the peloton.
Tour riders will tackle it for the eighth time in the history of the race, from its tougher south side, before a final 7.4-kilometre uphill effort to Tignes ski resort. The last kilometre is rather flat and seems ideal for a sprint between the best climbers.
STAGE 20: Albertville to Val Thorens, 130 kilometres, July 27
In their bid to maintain suspense right up until the end, Tour organizers have set up an ideal stage for a final showdown in the Alps.
On the eve of a final processional stage to Paris, yellow jersey contenders will be taking on each other on a royal battleground featuring three climbs and technical downhills. Capping the highest Tour in the race history, the final climb to the ski station of Val Thorens, at an altitude of 2,365 metres, is more than 33 kilometres, at an average gradient of 5.5 per cent. Good luck with that!
