(This post is in response to Annick's questions, thank you for the idea.)
When you arrive in Incheon airport it's super easy to just hop on the subway with your bike, however that is not the case in Busan. Gimhae airport is located just West of Busan city and it is connected to Busan by a light railway train. It is an automatic elevated train and no bicycles are allowed on it.
So how to get from Gimhae airport into Busan? Or how to get from Gimhae airport to the Nakdong river path leading to Seoul? Or how to get from Busan to Jeju by plane? Well of course you can take a taxi, if the driver agrees and if you take your wheels off. Some airport buses would probably let you store your bicycle under the bus in the luggage department.
But the best option yet is to simply ride your bike.
Few people are aware that the airport is 1,5km away from the Nakdong river bike path. So with a little GPS and Google or Naver maps it should be super easy to navigate yourself to the bike path.
Once you are on the path you can cycle down the West bank all the way to the first certification center, it's about 10km. If you happen to be doing that in the last week of March or the first week of April you will cycle through a 10km tunnel of Cherry blossom heaven on a dedicated bicycle path.
Near the end of the lane of trees the path will turn to cross the river and you will soon see a sign for the certification center. After the certification center you can cross the rest of the river and start the route on the East bank of the Nakdong river and head to Seoul. Or you can cross the bridge and go straight for 1 km to reach Hadan subway station. From Hadan you can take the subway to anywhere in Busan.
If you cycled from Seoul, ended in Busan and want to take a plane to Jeju, you can cycle from the certification center to the airport.
Yes you can get away with putting your bike on a KTX, any train car or under a bus, but it may involve taking off your wheels, having to make sure there's space between all the luggage or pretending not to know rules and hoping not to be caught.
And so traveling between cities, if there is a train option with cycle racks available that will be my first option. There's always space, no taking wheels off or stressing about being caught.
But how do you find trains with bike racks? When do they run? Between which cities and where can you buy tickets or check? These were questions that kept me from using this care-free service. The answer is the Korail App!
Unfortunately it's all in Korean, but if you know your Korean letters you can book tickets easy on your phone and secure a bike seat and know which trains have bike racks. There are lots of tutorials online that explains how to use the Korail app, just do a simple google search, but they don't show you how to check for a bike rack.
I took a few quick screen shots and tried to show how you would find a ticket for yourself and your bike. It's not pretty, but hopefully it's useful.
I've taken the train from Haeundae to Ulsan and back a few times now, once I did not even have a bicycle ticket, because they were sold out. So I checked the time of the bicycle train and just got on it anyways, there's 5 bike racks, but lots of space available for more bikes.
Once you know the time the trains come and go, it's pretty much the same for each day. Every day at 7:38am a train with bicycle racks leave from Haeundae station.
For the trains near Haeundae and Ulsan the bike racks are always in the cafeteria car, number 4. If it's not a bike friendly train they take out the cafeteria car, so the train has car 3 and 5, but car 4 is just missing.
I'm already planning my next train cycle trip, maybe Miryang or Gyeongju...
Busan Bus Terminals
Many cyclists arrive in Busan after completing their epic Seoul to Busan bike tour. One of the biggest questions after giving your bum a rest and celebrating your achievement is how to get back to Seoul. There are 4 bus terminals in Busan, knowing which one to use can be very helpful.
Busan Central Bus Terminal (Nopo st.)
Seobu (West) Bus Terminal
Any information about cycling in South Korea.