Its seems to be a matter of how far down you want to take your bike apart - Smallest dimensions being the frame with the wheels, fork, crank, and derailleur removed - This can sometimes get you down to 30" to 40" ball park - It also might be worth it to ship the frame and wheels in separate boxes - Knew someone who did this when taking a bike on a flight and only got charged for two extra bags at 25$ each instead of an over size item at 130$...