There is a lot of rock in the hills behind Ulldecona, and a lot of shelter in it. Abric d'Ermites VIII is another of the painted overhangs in the same range as its neighbours, a short stretch of cliff where people thousands of years ago left red figures of animals and hunters on the stone. It belongs to the Levantine tradition recognised by UNESCO, a style found along Spain's eastern side from Catalonia down to Andalusia, and it is a close neighbour of other numbered shelters here.
They point to the area and not to a signpost, and the shelter is a walk from where you leave the bike. Spend a few minutes studying the surrounding rock before you go looking, because the paintings are small and the overhangs are many.
What makes the afternoon worthwhile is the country. This is the edge of the Ports de Tortosa-Beseit mountains, where Catalonia meets Valencia and Aragon, a rugged range with some of the best twisty roads in the region. Wild goats live up in the rocks, and eagles ride the thermals above the ridges. The tarmac in the foothills is narrow but mostly well kept, with a succession of bends that suit a middle gear and a patient hand. In the valleys below, almond and olive trees stand in rows on stone terraces that have been farmed since Roman times and probably earlier.
Fuel in Ulldecona, about six thousand people, is easy. Santa Bàrbara, to the south, has fewer services but is on the way. If you are planning a longer day, remember that the villages up in the mountains tend to close early, and some have no pump at all. Fill up before you leave the plain.
Late April and May are the best months, when the hillsides are green and flowers crowd the verges. September is also a good bet, with warm days and crisp mornings. In the middle of winter, the high ground can ice over, and the coast road catches the wind off the sea. A flask of something hot and a windproof layer will do more than any amount of kit.