This is not the shortest route to climb Cabezas de Hierro but it is probably the most easy though you have to ascend two heights before, Bola del Mundo (2.255 m) and Valdemartín W summit (2.272 m). The route (PR-11) is almost the half of the famous Cuerda Larga,
the ridge between Puerto de Navacerrada (1.860 m) and Puerto de la Morcuera (1.796 m).
The base of the climb is Puerto de Navacerrada (1.860 m).
See Getting There here
for reaching this known road pass.
Once on Puerto de Navacerrada take the road in front of the famous Venta Arias, leave the lower chair lift station
to the right and ascent on a concrete track. Firstly it is in parallel with the chair lift cables. The track passes below those cables and then it has a sharp curve to the left. It passes below the cables again and turns to the right tightly, towards Cuerda (ridge) de las Cabrillas, where La Barranca and Garganta (creek) del Infierno can be well viewed. Then the trail turns to the left and divides in two branches wich join after some dozens of metres. Leave the upper chair lift station
to the left, it is close to Primera Guarramilla (2.178 m). Continue on the track towards the TV station placed on Bola del Mundo (2.255 m)
summit. Leave Segunda Guarramilla to the left (2.225 m) and desdend slightly to a less marked col. Ascend to the TV station (1h) surrounding the buildings and anthens leaving them to the right.
Descend NE wards to Collado de las Guarramillas (2.158 m - 1h 15 min).
While getting this col you can see Peñalara massif, the upper section of Lozoya valley, Valdesquí lifts and ski-runs to the left; Manzanares creek, Collado del Piornal (2.073 m), Maliciosa (2.225 m) and Peñotillo (2.123 m) to the right. The trail now is marked with red and white paint. Once on the col ascend to the right of a ski-run, leave a little construction with a metal post on the roof to the left and reach a flat. Turn to the left, towards Valdemartín W summit (2.272 m - 1h 35 min).
Once there you can see the Cabezas de Hierro to the E-NE. Descend to Collado de Valdemartín (2.151 m - 1h 50 min)
on an earthy path and start the long ascent on the W ridge of Cabezas de Hierro. There are three easy and little steeps before the stone field wich is below Cabeza de Hierro Menor (2.376 m)
summit. Ascend towards a rocky rib near the top and reach it easily (2h 30 min). Continue on the summit ridge and descend steeply to the right. Leave another stone field to the right heading for the col (2.321 m)
between both Cabezas de Hierro. Continue on light slope to the summit of Cabeza de Hierro Mayor (2.381 m - 3h).
It can be done on the same track of the ascent.
The timetable is this: Cabeza de Hierro Mayor - Collado de Valdemartín (4h) - Valdemartín W summit (4h 20 min) - Bola del Mundo (4h 50 min) - Puerto de Navacerrada (5h 40 min total).
Try to avoid the hotest days of July and August
and take a lot of water in summer, wear a cap and never forget a jacket. In late autumn and early winter take warm clothes, crampons and poles (or a long ice axe) with you. If attempting in late winter snowshoes and AT skis could be very useful. Never forget compass and map, from autumn to spring they could be advisable because of the fog. An altimeter could also be good.