The route starts at Castejón de Sos along the N-260 in the direction of Laspaúles. Just before we have completed 2 kilometres of mild slope, we turn left at the detour leading to the towns of La Solana, Urmella and Arasán. A series of continuous curves allow us to quickly gain altitude and find the detour to the right which leads to Urmella. Follow the opposite branch towards Arasán. These first three kilometres are hard, with slopes exceeding 10%. Before reaching Arasán, the slope looses steepness and, once we have passed the town, the path continues downhill for one kilometre. After crossing a ravine we begin an agonising uphill stretch, a tough test for any cyclist that wishes to get to Liri, the second town in our route. We cross past the farmhouse and continue our ascent, interspersed with a some extremely steep slopes along the way. The final kilometre to the farmhouse of Ramastué (1,366 m), which features a fairly flat gradient, will allow us to catch our breath again.