I've always carried my bike in a hard case. All I have to do is remove the wheels, handlebar, pedals, seatpost (with saddle) and rack, all of which can fit in the travel case with the bike. I have never been charged a fee except once on the return leg from Canada. However, I have not flown my bike for awhile, so things may have changed a lot. I am aware, however, that Lufthansa still considers the bike as checked luggage.