From Ronda de Dalt, at Vallcarca exit (6) take the Ctra. Rabassada to the top of the hill. Nice viewpoints medium difficulty, evalation about 300m. Pass by Tibidabo Theme park and Torre de Collserola, two landmarks of the city. Go to the Observatory where the paven road ends to see the city once more. On the left of the Observatory take the downhill path, technical but not long, that will take you to the dirtroad. Follow its dowslope and get on the next trail on your left a few meters after a water tap. This bit is medium speed, but very techincal, pitt it lasts only for 200m. You are at the base of the Tibidabo Funicular. Follow the aslphalt to the Ronda de Dalt.