A few things I just remembered and wanted to add.
Depending on the size of the bike box you get (assuming it is cardboard) you can get away with a few things. Try to get a box where a bigger bike was shipped in (i.e. 55/56cm.)
I managed to get away with the following:
1. Seat post - I didn't have to remove it, but I marked it off with electrical tape a few times in case I absolutely had to remove it.
2. Handlebars - I didn't have to remove it off the fork. I simply turned it sideways but still marked it off with tape in the event I had to remove it.
3. Rear derailleur - Like the items above, I didn't have to remove it, but I only ever took this chance once. Nothing is shittier than finding out your rear derailleur cage was bent.
I was able to fit in the wheels etc. into the box with ease. Most recently, I got a box meant for a 50cm bike. While I managed to fit everything in the box, I had to play Tetris a few times to make it work, but that also meant having to disassemble the items I mentioned above, and then play Tetris again to make it work.
Having said all this, I travel with my bike enough to the point where I should probably invest in a bike travel bag. Fucking dumbass bcrdukes.
