In the national park all trails are restricted. This route is not suitable for cycling. You risk a penalty. On the Guadarrama National Park page there is a map with the cycling tracks. Before saving please check these things
El Nevero is one of the highest and most important mountains in the Guadarrama Mountains, at 2,209 meters above sea level. It is located on the border between the Community of Madrid and the Province of Segovia. As it forms part of the Guadarrama Mountains National Park, access to it by bicycle is prohibited, as fines may apply.