In reply to JdotP:
Always pack the bike out wth stuff - tools in an old wash bag, travel track pump, spare tubeless sealant, DIY tubeless inflator etc. Helmet usually not.. I don't take C02 any more - PITA with tubeless - less is more if you've got an oversize leak - I find that CO2 just blasts out, so I just take a mini-pump. You're allowed 4 cylinders as hold or hand baggage.
Taking shoes helmet and pedals separately is a good idea, if there's anywhere to hire a bike...
Inflatable roof rack (for bike box on hire car) also goes inside box. Sometimes a seasucker roof rack instead, depending on local arrangements, goes as hand baggage, just for the fun of unpacking it for a bemused security guard