Actually...
Bug Out Bike is not a new idea.
I'm 51 and recall Mentors and Elders, Sharing how in various conflicts, from WWII to Vietnam how useful the bike was.
Some shared stories about the Depression, Natural Disasters such as tornados, flood, fires...
I remember the '68 riots, and folks using bikes - I did, and was carrying my revolver. I have used a bike during tornados and floods as well, I used one in '78, and Steel Combat Commander.
Others were using Canoes, and Jonboats in the city. For instance a Kmart store was under water...as were a number of car dealerships.
Medical / Rescue used watercraft , and bikes used to get supplies into and out areas, or communicate and coordinate efforts.
Quite a few folks have/ are hoarding the OLDer bikes. Plain vanilla, no speeds, no caliper brakes - just Bendix Brakes on the rear. Bigger tires and stronger frames to take more rough terrain.
Bikes like I grew up with, we went down curbs, down steps, hit potholes and bikes were not "delicate". Pretty much maintanence free...easy to fix.
IIRC my first bike was a 24" model, and sold for $29.95. It was made by AMF.
It lasted - until stolen -.
I bought another one, used, because someone wanted a Three Speed Bike.
I paid $20 for it, and it lasted for ~ 20 years until destroyed in a fire.
A simple kid's sized canvas Golf bag with carrying strap will hold a Lever Action , a shotgun, Marlin 60...the little pouch for golf balls holds other "needs".