Word of advice for those who want to take their bike on the train here in Belgium. Try to avoid peak hours when boarding a train ( 6.30 till 9 in the morning and 4.30 till 6.30 evening ). It will be too crowded seeing many regular commuters will take up space with their folding bikes.
In most of the intercity and interegion trains there are designated carriages where you can sit next to your bike to keep an eye on it.
If visiting a town I would advice though to park your bike at your accomodation or in a guarded parkinglot seeing the area around the trainstation is notorious for getting your bike stolen.
Belgium has great routes for cycling ( the Netherlands are champion of course when it comes to decent roads for cycling ! ) to Santiago. Especially the Via Monastica and before you know it you will have reached the border with France...
There is also a list of people ( Flemish Confraternity of St James ) who will accomodate " Pilgrims on the bike ".
But back to the topic of your actual thread. It all sounds easy and convenient, but you need to be aware that there are only a few places for assembled bikes on French trains, and if they’re taken you have to wait for the next one.
I'm unlikely to need your very useful link, and know this is not the point of the thread, but just to say... @mspath, you are an inspiration.
The image of someone pushing a 3-speed up those switchbacks? Oh, my.
Indeed - Ultreia in all things!