The route leaves Guadalix de la Sierra, passes through Miraflores de la Sierra and climbs to the Puerto de Canencia. On the other side it drops to the village of Canencia and ends in Garganta de los Montes, in the Lozoya valley. The pass itself is on the M-626 and M-629, with links on the M-611 and M-969.
It crosses the municipalities of Guadalix de la Sierra, Miraflores de la Sierra, Bustarviejo, Canencia and Garganta de los Montes. It is a more modest mountain road than Navacerrada or the Morcuera: narrower, tighter and with the forest right up to the tarmac, with pine woods and, on the Canencia side, areas of birch. The descent to the Lozoya is quiet and leads to small stone villages.
It is about 35 km and a little over an hour without stops, with around 90 bends and four hairpins. Altitude ranges from about 850 m to 1,524 m. As the road is narrow, expect cars and cyclists taking part of your lane on bends, and leaves, dirt or damp under the trees. Take it slowly in the shaded sections.