This part of the trail can get "pretty gnarly". Lots of elevation "ups and downs" once you're off the "rail bed", not to mention the thorny plants, poison ivy and nettles. Also ticks. Probably not for kids, unless they're "tough". If you can't deal with these things yourself, probably leave this 'til late fall, winter or early spring.
As I bike this nice, flat, paved trail . . . I wonder at the work that people did, using hand tools, animals and steam powered "heavy equipment" to cut through the tops and fill the stream cut valleys through this rolling terrain to bring the product from farms and ranches to the port in Duluth, then to ports around the world. Amazing.