This June I was again in MT riding and did some of the L&L from Missoula, only in the opposite direction. Three Forks, MT to Twin Bridges, MT is pretty easy. The free (donations of supplies and/or money are appreciated) Bike Camp in Twin Bridges is a great place to stay and is a nice place for a day off. Despite being a small town, the place has everything, including a good grocery store, library with Internet access and a laundry.
Beaver on the bank of the Beaverhead River at the Bike Camp:https://www.flickr.com/photos/105349603@N05/27402614413/in/album-72157667672266654/
Twin Bridges to Dillon is a gradual climb, and there is a section with no shoulder. I recommend riding early. Haven't been to Dillon in more than a decade, but I remember it having everything. Then you hit the mountain passes. At the top of Big Hole Pass, take a break and walk the gravel path to the interpretive boards. The view is terrific.
Someone renovated an old hotel building in Jackson. You can also camp on the lawn on the side of the building. The only other option for lodging is camping or a room at the hot springs lodge across from the hotel. Depending on the time of year, they may have limited hours during the week. There and the café in town are the only places to get food. (The mercantile closed several years ago.)
Wisdom has free camping on the edge of town, a motel, small grocery store, bar and a yummy bar/restaurant called The Crossings at Fetty's. Mosquito repellant is an extremely good idea for all areas mentioned above.
For the most part, the climb up to Chief Joseph Pass is not steep until the last five or six miles. If you don't mind dirt, the Gibbons Pass alternative saves you some miles. The climb up heading north is pretty mellow, and the road surface was in good shape when I came down that side in 2014. However, the descent down to U.S. 93 to Sula is quite a different story. It's narrow and bumpy in places. There are warning signs that it is not maintained for vehicles. But if you have the skills and the appropriate tires, it's worth it. It truly is like being in the backcountry. I was going to do it again this year but it rained hard all night so I stuck to the pavement.
Assuming you take paved MT 43, it's all down hill once you reach Chief Joseph Pass. Note that the rest area on U.S. 93 near the junction with MT 43 at Lost Trail Pass has been greatly improved over the years. There are now plumbed bathrooms and drinking water. The downhill, to one degree or another, basically lasts until north of Darby. You'll pass by a store/restaurant/campground in Sula. The place shuts up tight at 5 p.m., although you can still pick a campsite and pay in the morning. Groceries are pretty limited. This year I camped further north at U.S.F.S. campground Spring Gulch. Small place right along the river with a biker campsite:https://www.flickr.com/photos/105349603@N05/27396112204/in/album-72157667672266654/
Again, if you don't mind mellow dirt with some relatively easy climbing and descending, the partially unpaved Old Darby Alternative to Hamilton is fabulous:https://www.flickr.com/photos/105349603@N05/27395724003/in/album-72157667672266654/https://www.flickr.com/photos/105349603@N05/27396112384/in/album-72157667672266654/
(Those are actually some of the lesser scenic photos I have of that stretch.)
It's my understanding that, as of this summer, you can now take a bike trail all from Hamilton into Missoula. The last piece wasn't open when I started my tour back in mid-June.
And that's all I have to say about that.