There's several. The ones on the south side goes from roughly the radio tower to the R21 gate, and is 99% downhill. There's basically two options there, the 'tree to tar' trail and the jeep track / tweespoorpaadjie that runs next to the fence. The trail gets hairy, as it's lots of loose and sharp rocks, and at the moment is very washed out. On the North side you go from the radio tower down to a split, where you can hook a short left to the reservoirs and back onto tar (short, maybe 1km in total) or hook right down to George storrar corner, from where you can hit the fenceline back to the R21 corner and then uphill back to the R21 gate, or you can go left and UP what is locally known as the WTF climb - 7% and loose which also comes out near the R21/George storrar corner, for the climb back. A favourite loop is down the south side, over the tar, down next to the R21 fence to George storrar, then up to the Radio tower, and from there either back down the south side or down by tar. There's also a 'proper' downhill track from the entrance to the fort to the R21, but at the moment it is not recommended, super washed out, jumps broken and pieces missing.
