Tour de France - the mountains....

The 100th Tour de France features six high mountain stages including four mountain-top finishes. Here's a guide to where the Tour might be won...or lost. Settle down in front of the TV - ITV4 - and enjoy!

STAGE 8: Ax3 Domaines
The significance of this one isn't its steepness (not too steep, relatively speaking) nor its length (not too long). It's all down to location, location, location. This is the first mountain top finish of the 2013 Tour, which is the point when the race will truly take shape. The critical factor is that for a stage finish here, the spectacular, narrow and steep ascent of the Port de Pailheres can be included immediately beforehand, with only the descent to Ax-les-Thermes separating the two - quite a combination

STAGE 9: Col de Pevresourde
There are longer Pyrenean climbs and many that are far steeper, but few boast the scenic splendour of this one; the long, sweeping hairpins across a verdant high mountain meadow. the Pevresourde harks back to the first true mountain stage of the Tour in 1910 - when it crossed in the other direction - the long steady climb up from Bagneres de Luchon has been a regular feature ever since.

STAGE 15: Mont Ventoux
A standalone peak south of the Alps, climbed 14 times in the Tour. The Giant of Provence is unremitting from the wide bend at the foot to the final past the observatory at the peak, with dizzying 360 degree views of southern France. It's also unique; a Tour climb that goes up a mountain from the foot to the very top, rather than to a ski resort on a plateau, or over a pass between higher peaks. It's horribly steep with no place to rest - just a direct pull straight to the summit - Gary and I know what this one feels like!

STAGE 18: Alpe d'Huez
If there is one place that sums up the madness of the Tour de France it's the Alpe - the craziest crowds, the toughest gradient and a wealth of history. What's special this year is the riders get to climb it twice, using a newly refurbished descent out of the resort over a second climb, the Col de Sarenne. Ther's no run-in to the Alpe, the peloton comes along the valley then the riders hit the first, and steepest, hairpins - like a wave crashing against a cliff. That instantaneous suffering puts Alpe d'Huez in a class of its own.

STAGE 19: Col de Madeleine
First climbed by the Tour in 1969, the Madeleine has become a regular feature as one of only two routes between the maurienne valley to the south and the Isere to the north. It's evenly graded but unremitting and runs the full gamut of mountain scenery: forest at the foot, flower filled meadow worthy of Heidi up top and a ski resort in the middle with craggy slopes at the summit.  

STAGE 20: Annecy Semnoz
Very, very steep - with a nice restaurant on the top. Spectacular views on a clear day - the final climb of the Tour is also the steepest - like the Ventoux, there is nowhere to rest, no respite as the road twists up the hillside at between 10 and 16% - this one comes when the entire field will be wrung dry after three weeks of racing.