My wife and I have used this method many times for air (international and domestic) and rail travel:

We each a have large lightweight duffel bag (approximately 8 oz; mine is yellow and her's is black. The contents of my 4 panniers, and the contents of her 2 panniers fit in our duffel bags. The empty panniers go in the bike boxes, providing addition protection for the bikes. The duffel bags go as checked baggage. On tour the bags are rolled and carried in the bottom of our panniers.

The more fragile items (notebook, chargers, etc.), along with clothes, are packed in the red and yellow rackpacks, and are carried on along with our bar bags.

My wife can easily handle all her gear in airports and train stations.







This is all our gear for a 3 month tour, including camping/cooking equipment.