Middle Frisco Trail is a 12 mile lightly trafficked out and back trail located near Del Norte, Colorado that features a lake and is rated as difficult. The trail is primarily used for hiking, trail running, horses, and mountain biking and is accessible from May until October. Dogs and horses are also able to use this trail.
Another option; you can take the West Frisco ATV trail up (a slightly easier climb), and the singletrack Middle Frisco trail back down. The two combined form a nice loop trail.