I've started thinking about 2022 travel and possible bike tours in Croatia. These would be 8-9 days, running from Zagreb or Split to Dubrovnik (or reverse, depending on company). Open jaw flights seem a bit more expensive than round trips, so I've just researching what surface transport would look like from the tour end point to the start.
I immediately notice there does not appear to be train service to Dubrovnik, bus only.
Another consideration is, depending on the tour company, taking my own bike. Some company's bike rentals are better thn others. That adds a bike travel case (as much as 47x10x30 inches) to be wrangled around as well as medium suitcase and small backpack. Wrestling the back case onto a train can be a hassle. Airlines frequently charge extra for bike cases.
(Medium suitcase: I could do with a US-sized carry-on if not biking, but biking adds multiple bib shorts & jerseys, bike shoes, helmet, saddle, pedals, rain jacket, etc., etc., etc.)