Ripfest singletrack. Very fast, very fun. Can be ridden either direction, however, you will have to ride Tom Blake Trail, Stark's Trail, Cross Mtn. Trail or Government Trail to access Powerline.
From I-70 exit #116 and take Hwy 82 towards Aspen, around 35 miles. Take Brush Creek Rd. 5 miles to Base Village. Parking is abundant.
http://www.singletracks.com/item.php?c=1&i=3817