Acha-san

Overall difficulty level: 9/10

Skill: 10/10 (all routes)

Aerobic: 8/10 (depending on route)

Scenic: 5/10

Crowdedness: 3/10 (9/10 on Saturday afternoons and all day Sunday)

Acha-san is one of my favorites. It's got steep ups, steep downs, steep granite fields, steep dirt singletrack, a steep walk, and almost all of it is rocky. Needless to say, this trail network requires quite a bit of technical skill. The network actually consists of two mountains, Acha and Yongma, which run roughly parallel to one another. At the north end of Yongma-san is Manguri, the biggest mountain cemetery in Korea. Unlike western cemeteries, it feels more like a park, with badminton courts, so-called spring water (yaksu), and yes, trails. This side of the mountain is not so difficult, and novices may be content to ride the paved ring road in Manguri, from which you can access many of the trails, as well as easier routes not mentioned below. Manguri also makes a good place to start the "real" ride. Elbow and knee pads are highly recommended, as much of the trail is pure granite, with dropoffs on 35 degree pitches and the like.

Access: Acha-san is in eastern Seoul. The most traffic-free way to get there is via the Han River Bikeway, which is on the south side of the river. In any case, open a map and look for a big open space between Seoul and Kuri (a satellite city to Seoul's east). That's where you want to go. On your map find the Sheraton Walker Hill Hotel. This is the southern border of the ride, and is the best place to finish the ride, although you could start there if you like. Just keep following the ridge. Anyway, look north of here and find the major road that connects Seoul to Kuri. At the top of this road, halfway between the cities, is the paved entrance to Manguri, the northern border of this ride. Very roughly, you can follow the ridge from this point to the Sheraton and hit most, but not all, of the course.

Suggested coursing: I like to start at Manguri (which you can do from many access points), head over Yongma via the main ridge trail to Acha, down the Acha ridge, heading off past the pagoda to the granite fields. I don't go down this wide-open field, however. There is a better trail to take down: a steep, tight granite singletrack winds its way back to the bottom of the granite field, which I try to ride up (with much effort). Back up at the pagoda, I turn right at the ridge and continue up the other side of the saddle, where at the top I turn left at a fork and follow a decidedly unscenic barbed-wire-lined tight singletrack down to a quarry-like area This eventually opens up to reveal a road, which I then take back to the Olympic Bridge and the Han River bikeway. About 14km/90 minutes.

Additional notes:

--Steve Danyo