What train ticket do I need to buy to take a bicycle with me on the train to Belgium?

score:5

In a terribly long 1 hour call with NS International I managed to book a train+bike ticket.

To answer my own question, here is what I learned:

You need the 12 euro international ticket, regardless of any regional trains before/after the international part.
It is only possible to book a ticket by phone or at a physical NS International desk. Booking a bike ticket on-line is impossible ^{It's only the year 2021 after all...}
If using the phone, you need to pay by credit card and hand over all your information (name, d.o.b., credit card number, CVC code).
Tickets are linked to a name, you need to show a photo ID when a train conductor checks the ticket. If buying by phone, triple check that the person on the other end got the name right, as otherwise they might misspell your name and you need to call (and wait) again to get that corrected.

Saaru Lindestøkke 3799

Source: stackoverflow.com