Blue Creek Road is really nice. The Pryor Road to Old Hardin Road can have some potholes and has a lot of patches But the Blue Creek Road and the Old Hardin Road over Lockwood pass are really great Biking roads.
On the Frontage Road and riding 56th back to the frontage really pay attention to traffic at intersections, they can be dangerous. The rural road from Laurel to Molt Road and Back to Billings is great!
I am a UK resident, I come to the USA for the roads, and to TOUR NOT RACE with my Buell riding friends from Denver,
I can tell you this road is one of the reasons i come to the USA a rollercoaster of a ride, corner after corner after corner, some constant radious corners return (switchback...