The route leaves Alhama de Murcia, enters Sierra Espuña and climbs through the Huerta de Espuña to Collado Bermejo, then drops down the other side to Totana. It uses the RM-502 and RM-503 and lets you ride both faces of the range's classic pass in one go, from one town in the Guadalentín valley to another.
The ride runs through the Bajo Guadalentín comarca, in the municipalities of Alhama de Murcia and Totana, and crosses the Parque Regional de Sierra Espuña. The contrast is clear: you leave the farmed plain of the valley and within a few kilometres you are in pine-covered mountains, with views back over the valley as you gain height. It is a proper mountain road, narrow and very twisty.
It is about 39 km and roughly an hour and a half without stops. You go from around 200 m to about 1,200 m at the col, and some 235 bends are counted along the way, including about 22 hairpins. The road is narrow in many places, with limited visibility on the tight bends, and you will often meet cyclists, walkers and visitors' cars heading into the park, especially at weekends. There may be gravel and pine needles on the surface. In summer the valley is very hot.