I have packed a disc bike in a bike box and in a bike bag to travel overseas. Both times, I kept the rotor on and packed the front wheel beside the crank with the rotor to the frame and the wheel tied to the frame with zipties. The rotor does not touch the frame and is protected from damage. The wheel is more likely to be damaged by very rough handling than the rotor. I have not had damage to the bke occur over 4 x 12000km return trips .