Take your bike in a plastic bag on an aeroplane
Let me call it XXL-Bag. At some airports, served by British Airways, you can buy an XXL-bag for 5 to 10€. It's really big enough to put your bike in. These plastic bags are strong. You can use them for at least 6 to 10 flights. You can fold this bag, it just weighs 200 grams. Easy to transport somewhere in your luggage from A to B.
Instructions how to pack your bike in a bag and check it in