My friends at Western Spirit Cycling have a great bike trip in Idaho – the Lewis and Clark trail – This is listed as one of  Outside Magazine’s Top 25 Trips of a Lifetime. You can contact Western Spirit Toll Free: 800-845-2453

Some trip specs:

Road Surface: Clay and gravel primitive road.
Technical Difficulty: Easy to Moderate.
Physical Difficulty: Moderate to Difficult, a significant amount of climbing.
Altitude: 3,000 – 7,000 feet.

However, the best way to get an idea for this trip is by the following video