I've built the cardboard bike box for my flight to Frankfurt from Seattle. I plan to ditch the box at the airport, then set up my rig like this for the trip into the city. My ticket on United limits me to one piece of luggage, 50 lb, at no additional charge, plus carry on. Before I fold and pack the bike, and stuff about 11 lbs of gear around it, it's wise to do a test run. I used this configuration for my New Zealand trip in 2011, so I know how to make it work. Too squirrelly for long distance touring, but should work fine with my plan to travel point to point on the Deutsche Bahn trains.
The rest of the gear needs to go in my carry on bag, so I'm testing various configurations to make it work.
The red item is a canvas bag, which I'll use to corral the tent and the dry bags when hopping aboard trains. William the Conqueror will fold and on this trip I'm bringing along its clever black bike cover which turns a bike into a sort of wedge shaped canvas bag. Two pieces of luggage plus carry on. Done! This configuration avoids both the steep oversize luggage fee for a full size bike ($USD 100-$200+) on a plane, and the 5,00 Euro bike fee for a full size bike on the train. I have a rail pass that allows 10 days of travel in one month, so if I don't have to pay to load a bike, I have 50,00 Euro to spend on cuckoo clocks, slices of chocolate cake and beer.
In addition to this kit, I'm taking dress clothes and a large picture hat for a wedding in Baden Wurtenburg. My plan is to mail these items on to a friend in London post-wedding. I'm still mulling my options on managing these in my carry on. I am confident I'll figure it out. Several years ago, I brought a wedding cake from Australia on a Qantas flight, and served it at my own wedding. Formal clothes should be somewhat simpler.