The Route of the Hiawatha is a 15-mile packed gravel trail that runs from St. Paul Pass, near Roland, Idaho, to Pearson, Idaho. A 31-mile section is planned in Montana, but it hasn’t been built yet. A small portion of the trail is open to motorized traffic, and the rest is open to horses, pedestrians, bicycles, and other non-motorized traffic only. It’s a rail-trail, and involves several tunnels, so you’ll need to bring a light!
The trail is open starting in late May or early June, through late September or early October every year. There is a fee to use the trail ($10 in 2012), and many people take a shuttle bus operated by the Lookout Ski Area (about $10) between the Roland and the Pearson trailheads, and ride down.
I personally haven’t ridden it (yet!), but I’ve been assured by several people that the surface is packed and would be fine for regular bikes (as long as you are comfortable riding on non-paved surfaces — probably you wouldn’t want to take an extremely skinny-tired racing bike though!). Also, several people have told me that the gradient is so gradual, you can easily ride both up and down if you don’t want to take the shuttle bus.
