“I’ve built bikes out of shipped boxes and they are normally pinned in place with heaps of excess cardboard and packing materials.”
Not from giant, Scott, merida , Dawes
I had some Moore large kids bikes once that were mind.
Bikes travel in boxes all over the world .
Just get the right size and remember how they were actually packed – axles and disk out of front wheel . Rear wheel stays in frame , pedals off handle bars off pipe lagging on down tube and top tube cable tie handle bars to down tube andseat out cable tie to bottom half of front wheel spokes then cable tie front wheel to down tube.
Loads of extra material is 2 bits of pipe lagging and a hand full of zip ties
Pedals , rotor and axle in bag and secured in place.