There is a downhill course in the woods out the back end of Ashton Court. Go out by the quarry onto the road, turn left. Straight over at the x-roads and as the road starts to fall just past the golf course on the right there is a gate to climb which will take you into Still Woods. Loads of DH there; it's owned and run by the uni and they don't seem to mind others appearing.

Still woods is a top place to ride but please don't build anything without permission. There are dig days happening on the second Sunday of the month - rummage through the forum on the Bristol Trails Group webiste and you should find more info.