I have just finished this route (May 2024), starting from Moulins all the way to Langogne in 4 days. Here is my feedback and advices:

- The first 60 kms from Moulins to Billy is the least interesting portion, small roads, average country sideview and no sight of Allier river. I don't know how is the Nevers to Moulins section but I would suspect it is the same and not worth it if you are short in time. The wildest part is after Brioude where the scenery is great (Small typical villages, Allier gorge, Cliffs, view on nearby mountains, Chapelles, etc.)

- There is a new dedicated bike path that just opened all the way between Pont-du-Château to Vic-le-Comte, which is very nice. There is also a bike path section between Billy and St-Yorre. All the rest of the route is small roads with very little car trafic so it is fine (except a few crossings).

- This route is not crowded at all, at least not in May. I met only 3 other bikepackers in 4 days ! It is probably much more in the summer time. However, if you are not camping (like me), you need to plan accommodation in advance, because there are very few hotels on the way. I can recommend 2 hotels where I stayed that were great for bike travellers: Original Hotel Larivaut in Puy-Guillaume and Hotel Poste-et-Champanne in Brioude. Finding accommodation between Brioude and Langogne is more problematic.

- In total my ride was 360 kms and 4300 meters D+. The Brioude to Langogne is more hilly (2600 meters D+ in 130 kms). For this part, you need to be reasonably fit with good & light bikes or electric bike. I used a standard gravel bike with 3 light bags (saddle, handlebar, frame) which were enough for 4 days without camping.

Benoit