I would like to stress that it is still possible - with care - to tour Yellowstone National Park.
I say that as someone who lives in Wyoming and has toured every mile of park roadway - many times.
Yes, there is considerable traffic, but planning and allocating sufficient time make the difference.
Still, for a bike tour across the U.S., Yellowstone is a major highlight.
There are five segments to consider on the TransAm:
(West-to-East)
1. West Yellowstone to Madison Jct.
2. Madison Jct. to Old Faithful
3. Old Faithful to West Thumb
4. West Thumb to Flagg Ranch
5. Flag Ranch to Colter Bay
Camping with hiker/biker campsites is available at:
Madison, Grant Village, Lewis Lake, and Colter Bay
Additional camping is at/near West Yellowstone (P), Flagg Ranch (P), and Lizard Creek.
Hiker/biker sites have a "No turn-away" policy - which permits late afternoon riding.
EASTBOUND -
1. West Yellowstone to Madison Jct. - 14 miles
Suggested time - Late afternoon/early evening. Greatly reduced traffic.
Moderate shoulders. Gradual uphill in river valley.
Overnight at Madison.
2. Madison Jct. to Old Faithful - 16 miles
Suggested time - Early morning. Light traffic early.
Backroads - Firehole Canyon Rd, Fountain Flat Rd, Old Faithful area bike trail.
Moderate climbing. Moderate shoulders on main road.
Spend midday hiking - few people venture more than 200 yards off pavement.
Restaurants and store. Historic Old Faithful Inn. Super busy.
3. Old Faithful to West Thumb to Grant Village - 19 miles
Suggested time - Late afternoon/early evening. Greatly reduced traffic.
Significant climbing, two mild passes. No shoulders. Fast downhill into West Thumb.
Overnight at Grant Village. Store, Restaurant, Showers.
4. Grant Village to Flagg Ranch - 22 mies
Suggested time - Early morning. Very little traffic southbound.
Rolling to Lewis Falls, then fast downhill. No shoulders.
Store/Restaurant at Flagg Ranch.
5. Flagg Ranch to Colter Bay - 17 miles
Suggested time - Morning. Most traffic still northbound.
Hefty climb on Rockefeller Parkway. Recently rebuilt with shoulders.
Overnight at Coulter Bay or continue on to Jenny Lake
WESTBOUND -
5. Colter Bay to Flagg Ranch - 17 miles
Suggested time - Mid morning. Moderate traffic.
Hefty climb on Rockefeller Parkway. Recently rebuilt with shoulders.
From Jenny Lake, start early morning. Stunning.
Late lunch at Flagg Ranch and hike along Snake River at South Entrance.
4. Flagg Ranch to Lewis Lake - 15 miles
Suggested time - Early Evening. After 6p. Little northbound traffic.
Major climb. No shoulders. Pull off as necessary.
Overnight at Lewis Lake. Have mosquito spray.
3. Lewis Lake to Old Faithful - 26 miles
Suggested time - Very early morning to West Thumb.
Skip Grant Village services turn-off to cross Craig Pass as early as possible.
Rolling to West Thumb. Two mild passes going to Old Faithful. No shoulders.
Restaurants and store. Historic Old Faithful Inn. Super busy.
2. Old Faithful to Madison - 16 miles
Suggested time - Late afternoon. Moderate traffic decreasing in late afternoon.
Backroads - Old Faithful area bike trail, Fountain Flat Rd, Firehole Lake Dr.
Moderate downhill. Moderate shoulders on main road.
Take time to explore thermal features - few people venture more than 200 yards off pavement.
Overnight at Madison
1. Madison to West Yellowstone - 14 miles
Suggested time - Early morning. Very little traffic westbound.
Gentle downhill. Moderate shoulders.
Riverside Dr. backroad option.
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If Madison is first/last overnight in the park,
I suggest camping well west of West Yellowstone.
West Yellowstone is an expensive tourist town and simply nuts.
National Forest campgrounds do not have hiker/biker sites.
Plan to arrive moderately early.
Although Jenny Lake is off of the TransAm route,
there is no more beautiful place to camp than its hiker/biker campground.
Fabulous hikes, camp store.
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I have biked most of the alternate route. Used to live in Jackson.
Teton Pass is steep, narrow, with heavy tourist and commuter traffic.
The Idaho side of the Tetons lacks the spectacular vistas.
North of Ashton is mainly wooded. Mesa Falls are nice on Hwy 47.
US 20 is unpleasant. Busy. The 2-lane sections have little to no shoulder.
I do not believe that it offers enough benefits to outweight riding through Yellowstone.
If - - - if - - - you plan, ride early, and give yourself enough time to do it gradually.
YMMV.
Pic - Yellowstone Lake at West Thumb