Recent personal experience with a bike on the Åndalsnes- Dombås route: You’re correct that it’s not possible to book a bike on this leg (make any other connecting reservations on a separate ticket so as to be able to book the bike on those trains). When I was there 28 June, there were 4 cyclists total waiting for the train. Train conductor told all of us that it was unlikely we would be able to board, due to expected heavy passenger load, lots of baggage, baby carriages, reasons, etc. We offered up removing wheels, etc. but received a very noncommittal reply. As I’m sure you’ve found, there are limited alternatives out of Åndalsnes that doesn’t involve the train or riding over Trollstigen (which was still closed while we were there). 5 min before departure, we were permitted to board with the bikes provided we could remove the wheels and all bags and stack the bikes on top of other luggage that was crammed in the vending machine area. Very stressful, but it all worked out for us. I completely agree with Matthew in that being forceful with the train staff and standing up for your rights is critical. In the end, how is a bike different than any other luggage others bring along?