Originally Posted by
indyfabz
I was going to suggest that, but it's not entirely off road....From St. Marie to Plummer you are on ID-3.
With that said, if the OP is flexible and willing to add some light traffic roads, I think it's a great option. The Hiawatha and the right of way between Pearson and Avery, with it's many tunnels and trestles, is a great ride.
I hoped you fill in some details on the route. I wasn't sure how strict the "off road thing" was and figured it was at least worth a look. This does look like a wonderful ride.
OP, here's a link to a young family that did the ride. From my research(a year ago), the only portion that REALLY isn't suggested for biking is the St. Marie to Plummer segment, ID 5 I think. The family in the link below got a shuttle to cover that part.
https://www.crazyguyonabike.com/doc/...id=554537&v=5f