The route leaves Guardiola de Berguedà and follows the valley up the B-402 to La Pobla de Lillet. From there the BV-4031 climbs to Castellar de n'Hug, and the GI-400 continues to the Collada de la Creueta before dropping into the Cerdanya as far as Alp.
The ride crosses from the Berguedà into the Ripollès and the Cerdanya through the municipalities of Guardiola de Berguedà, La Pobla de Lillet, Castellar de n'Hug, Toses and Alp. Castellar de n'Hug is a stone village hanging over the valley, and the source of the Llobregat is close by. Higher up the road comes out onto high mountain pastures up to the Creueta, with wide views over the Pyrenees. What makes it special is the climb: plenty of bends and hairpins in an increasingly open landscape.
It is about 52 km and around an hour and twenty minutes without stops, with around 250 bends and eight hairpins. Altitude ranges from about 720 m to just over 1,900 m. The Creueta road is narrow in places and there may be loose livestock and gravel on the bends. It is cold at the top even in summer and in winter there is snow and ice; check the pass status before setting out.