At 1,858 metres, Puerto de Navacerrada is the pass Madrid runs to when it wants to cool off. It is the crossing between the Madrid and Segovia sides of the Sierra de Guadarrama, and the road, the M-601 on the south side, climbs from Cercedilla and Navacerrada village in a series of tight bends through pine forest before bursting out onto the bare, rocky ridge. At the top there is a small ski area, a few ventas and cafés, a car park that is too small on every sunny weekend, and a view of the high peaks and, in winter, a rather charming scrum of skiers and bikers sharing the same tarmac.
The history here is stark. In the Civil War the pass was on the front line in the summer of 1936, when Republican forces held the Madrid side and Nationalist forces tried to push through. Remains of trenches and bunkers are still scattered through the pines. Long before that, the pass was an old route over the Guadarrama between the two Castiles, and there is a trail below it, the Camino Schmid, named for a German mountaineer who marked it early in the twentieth century.
For fuel and supplies, go down to Cercedilla, a town of nearly seven thousand people about seven kilometres away, or to Navacerrada village. The café and venta terraces serve decent coffee, hot chocolate, tortilla and soups, and the cold wind means you will want something warm. On clear days you can see down to Madrid, a haze of towers on the plain.
The riding is the real draw. On the Madrid side the road offers a satisfying sequence of hairpins and medium-speed bends, with good surface and mostly good visibility. The Segovia side is gentler and wooded, running down toward the old royal forest of Valsaín. On weekends the pass is busy with bikes, cars and cyclists, so a weekday or early morning is much more pleasant. Snow can close the road or demand chains in winter, and cold fog is common. Late spring, early summer and autumn are the finest times, with crisp air and dazzling light.