Mill D to Desolation Lake
This is a technical trail that can be ridden out and back, or combined with other trails for various loop configurations.
The uphill portion is grueling because it is steep. Coming back down can be fast if you have the skills needed to hop roots and rocks.
The trailhead is in Big Cottonwood Canyon, about 9 miles from the canyon mouth.
Desolation Lake(40.659573, -111.602518)
The out and back ride ends at Desolation Lake.