Actually - -
The large loop from West Thumb to Lake to Canyon to Norris to Madison westbound -
Or from Madison to Norris to Canyon to Lake to West Thumb eastbound -
Is so much better, anyway.
From West Thumb to Lake there are a long stretches where you are riding right along Yellowstone Lake.
(Plus, if you do the short Gull Point loop, you can have a very private time out on the point.)
From Lake to Canyon is the American Serengeti - with herds of buffalo in Hayden Valley.
The Grand Canyon of the Yellowstone is stunning - but missed by almost all TA riders.
Norris Basin is one of the best geyser areas - esp. in the evening if camping at Norris.
The ride along Gibbon River is quite pleasant - the road recently widened.
If you want to take in Old Faithful, you can always ride up from Madison Jct.
The stretch from Old Faithful to West Thumb is one of the worst to ride in Yellowstone.
Narrow, heavy traffic, and two passes with a dip and curve that gobbles up your downhill.
It's 30 extra miles doing the full loop - 60 if you add the Old Faithful leg.
That's 1/2 day for the loop - - 1 full day for the loop plus Old Faithful.
If you bike across the entire U.S. of A. - what's a half day?
Yellowstone traffic can be moderate-plus, even heavy at times.
The worst is at Old Faithful right after the geyser goes off and everybody leaves.
(That's why they have a ridiculous cloverleaf interchange in the park there.)
You can get the best riding in by leaving super early when roads are almost empty.
Plus, early riding affords you the best chance to see wildlife.
Also, since all campgrounds on the loop have hiker/biker campsites,
you can ride in the evening and enjoy hiking in the middle of the day.