Three Corner Rock Trail Professional Review and Guide
"Do you like riding switchbacks? I mean, do you really, really like riding switchbacks? The Three Corner Rock Trail will test your switchbacking ability as it offers an unofficial 65 of 'em in 9.2 miles of scenic, challenging singletrack. Three Corner Rock, perched atop the mountain at the upper end of the trail, can be accessed all on trail, by the part gravel road / part singletrack climb, or all on gravel road, which routes the ride as a 25.9-mile figure eight. Generally, the trail surface is a nice, forest-floor hardpack; toward the bottom some areas are rocky. Even if you're not a switchback master, the woods along the trail and the view from the top make it a beautiful place to polish that skill.
If you choose to ride the trail as an out-and-back, you get some respites from the climb on two one-mile sections on the lower portion of the trail. Other than that, you'll have quite a few uphill switchbacks to navigate. Those with less-than-expert technical proficiency are best off doing the road climb / trail descent. The length of the climb, the switchbacks, and total distance of up to 25.9 miles make this an advanced level ride. Great workout for the legs and eyes. Scenery: Meadow and Cascades views at the top, deep woods, and canyons."