Stage 18: Colmenar Viejo - Beceril de la Sierra
This stage is almost a carbon copy of the penultimate leg of the 2015 edition when Fabio Aru took the leader's red jersey from a tiring Tom Dumoulin and, the next day, claimed his first Grand Tour victory in Madrid. Although the start and finish towns are different, the four first-category climbs are the same, and could well produce another notable upheaval at the top of the leaderboard.
From the start in Colmenar Viejo, the riders will quickly reach the foot of the Puerto de Navacerrada, a steady ascent of 11.8 kilometres that rises to an altitude of 1,860 metres at a little more than six per cent. Later on, this will be the descent that leads into the finish at Becerril de la Sierrra.
The route drops to Rascafría, from where it begins to rise again on the western flank of the Morcuera pass. Like the Navacerrada and the Puerto de Cotos, which is still to come, the Morcuera doesn't have any abrupt ramps, but is a regular ascent, this side averaging a modest five per cent. It's the accumulation of climbing, though, that will exact a toll today. This quartet of passes add up to 50 kilometres of climbing with very little valley riding separating them.
What valley riding that there is comes between the descent off the Morcuera and the subsequent ascent of that same eastern flank as the route loops through Guadalix de la Sierra. This side of the Morcuera is a little tougher, averaging 6.7 per cent, and was where Aru dropped Dumoulin in 2015.
The descent off it quickly leads into the Puerto de Cotos, which lies on the same high ridge as the Navacerrada. At 14km, it's the longest climb of the four and won't be at all easy even though it averages a mere 4.8 per cent. Fatigue, the heat and the unrelenting pace that teams such as Jumbo, Astana and Movistar have set should mean only a very select group will be at the front coming onto the summit, before continuing on to the Navacerrada for that final drop towards the line.
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