Lolo Trail/Lewis and Clark
We spent 5 days camped at Wilderness Gateway on the Lochsa River in Idaho. My snooping around didn't turn up much singletrack in the area. The rec ranger suggested that we take our bikes up to the Lolo Motorway. Initially I poo-poo'ed the idea; after all who wants to ride dirt roads if there are trails, but it turned out to be an awesome day.
We drove up Saddle Camp road to the Lolo Motorway and parked our biked, headed west. We did ten miles out and back, for a total of 20 with about 3000 total elevation gain done in two long climbs. The road follows the ridge top, and in that part of the road it is pretty much exactly on the old Lolo trail and Lewis and Clark route also. It was deserted up there. My biggest worry and annoyance with forest roads is traffic - getting passed and eating dirt. We saw two vehicles, crawling along, in a 6 hour day. My understanding is that there has never been the anticipated traffic following the L & C bicentennial, and the road certainly looked not well traveled. It's a rough surface, high clearance type road, but not a horrible gullied out jeep trail.
It was crystal clear and hot up there. The bear grass is profuse this year. From the views, we could see all the way around from the Selway Crags, Bitterroot crest including (we think) Trapper Peak, Lolo Pass all the way around to the Mallard Larkins area to the north. Interpretive signage is minimal and general. We did a little side hike to the Smoking Place which has spiritual significance to the Nez Perce, and historical significance as it was a place of note for L & C during their trek across the mountains.
While it's not single track, it is spectacularly beautiful and very deserted up there. It would have been nice to have some better historical notes, like mile by mile for the historical route, but the FS pamphlets are pretty lame. We think it would be a great multi day trip to do with a sag - the non biker(s) could hike at the stop and drive the gear for the bikers.
My only complaint is that the bugs were unbelievable horrible and Deet resistant.
DH figured out the best way to pack our bikes with the boat:

Smoking Place interpretive sign. You still have to find the trail and hike to it; probably a good thing

Amazing views, looking SE

Top of the world?

East

The bear grass is profuse this year - very surreal looking
2015 Liv Intrigue 2
Pro Mongoose Titanium Singlespeed
2012 Trek Madone 4.6 Compact SRAM