South of Souel, Namhan Sansong is scenic regional park located between Songnam, Kwangju and Hannam. It's known for a continuous ancient wall capping ridges that surround a small mountain bowl at over 500 meters elevation, and long views out to Seoul to the north. The mountain bike rides combine rugged singletrack descents with paved climbs. There are 3 main trails down, each about 5 miles.
“Halftrack” heads west, to the satellite city of Kwangju. Its a slalom mountain bike riders dream: very narrow and at times quite steep. “Spongepack” is the easiest, but puts you the farthest away from civilization. It heads south to a road that runs between Kwangju and another satellite city, Songnam. “Big Mac Attack”, which heads north to within legshot of the Olympic Park in Seoul. After some intimidating rocky business at the top, it screams downhill, complete with berms, ruts, tight corners, dropoffs -- all on an amazing series of ridges.
To reach the mountain biking trailhead from Seoul, try the Line 8 subway to Songnam. The Sansong subway stop is already at a little elevation; from exit 1, just follow the big highway-like road uphill for about 0.5 km and make a left onto the two-lane paved road that goes into the park itself. This is the parks eastern entrance. Ride uphill for 3.2km to a tunnel. Don t go in the tunnel; instead turn right and continue 50 meters or so to the fortresss South Gate (Nam Moon). This park road actually continues through the fortress itself at the top, and descends west for about 8km on the other side, finally ending near Kwangju, where the western park entrance lies.
Info courtesy of Steve Danyo
Overall, Namhan Sansong is the 1st most popular mountain bike trail of all 7 mountain biking rides in Korea.