This trail is what mountain biking in Portugal is all about: beautiful views, rocky singletrack, barking dogs, and plenty of places to stop for a coffee and custard pastries.
Starting from the restaurant at the top of Foia, follow the sign for the Trilho de Foia ("Foia Trail"), which will take you along a paved road heading east. After about a hundred feet, take the right fork in the road and climb up between a chain link fence and a radio tower. Continue riding straight onto the unmarked singletrack with spectacular ocean views. (The Trilha de Foia, which is marked with red and yellow bars, splits off to the right.)
After a half mile of a singletrack, you'll meet up with a paved road and glide around a bend through eucalyptus forest. Take the first left onto the Via Algarviana, a doubletrack trail which is marked with a horizontal red and white bar. (If you continue a little further, you'll arrive at the gnarlier Foia Downhill Trail
.) As you descend, watch out for hikers and other trail users. Follow the trail for a mile, until you hit a paved road. Turn left and after 100 feet, you'll see the trail again on your right. The bottom section passes through thick forest and will spit you out in a steep, cobbled alley in Monchique.
Carefully descend to the center of town. Climb back to the summit on the 266-3 road.