From the lake Ibon de Urdiceto, ascent the ridge up to Punta Suelza. This is mountain biking/mountineering at its finest. Although loose, the beginning of the ascent should be fairly easy on well-worn trail. Soon, however, things get even more rocky and steep. At some points, you may need to ferry bikes up incredibly precipitous slopes. After busting your gut on the longest 2 mile climb of your life, your reward will confront you. All-encompassing views of the Central Pyrenees will unfold as you look down from your high perch.
Now the descent begins. Loose, faint, and exposed, the trail rockets down one of the mountain's ridges towards the forest below. Make sure you bring an extra set of brake pads with you for this ride; the sketchy surface you'll be riding on means you'll be riding your brakes the entire time. Because views of the surrounding mountains and of picturesque alpine lakes below will persist, remember to stop every once and awhile to soak up the experience and give your arms a rest. Before you know it, you be at the doubletrack road. Blazing down it, you'll eventually find yourself in Serveto