Some say the Hall, Heil and Walker are all over ridden while one of Boulder County's gems sits nearly empty, the Switzerland Tail. For those not familiar, the Switzerland Trail it is an old narrow gauge rail bed which has long since lost its ties and rails, winds its way from Ward (almost) to Sugarloaf mtn.
Since the trail is a former rail bed the grade is never very steep for the average rider and the trail conditions are tame enough that one could ride a cross bike or easily a suspensionless mountain bike.
My wife and I rode the Switzerland Trail by starting at the head of one of my favorite gravel roads in Boulder, WallStreet. WallStreet takes you back in time through many of Boulder's still visible mining remains.