According to their tool, it should be ok...
I know in Aalter that I can use a ramp to get on the platform.
In Leuven I'll have to use the elevator I suppose. Not sure yet if both the bike and trailer will fit in one elevator trip.
https://bikeontrain.belgiantrain.be/en/itinerary?fromName=Aalter&fromPlace=3.447848%2C51.0923&toName=Leuven&toPlace=4.715868%2C50.88228&selectedItineraryIndex=0&date=2024-06-22&hour=14&minute=45

