S.H provided an excellent reminder of a vital survival and prepper resource: the bicycle. I would like to add a few points. Commuters, tourists, and utility riders carry loads over various distances and terrain at non-athletic pace, so look to their example.
When selecting a bicycle, look for standard components such as tire size. MTB 26″ and Hybrid/touring style 700c are both common sizes. 29″ is the same as 700c. 27″ is not the same as 700c but may be your local standard for a similar fast/utility wheel. Bike shops now sell MTBs in 27.5″, which is a new standard (based on a boutique French size). It is non-standard and best avoided for prepper use. Folding bikes are never as strong but useful for vehicle carry. 20″BMX tire is std.
Avoid transmissions with very high number of rear sprockets. 8 or 9 is good. 10 or 11 is racing tech.
Practicality demands fixing luggage to the bike frame, so look for threaded eyelets for rack and fenders. Full suspension bikes lack luggage fitments. Commercial rear racks are all pretty good. Aluminium is the usual material but steel is used on premium expedition models such as Tubus. Commerical bags, esp touring grade ones, are very good and use quick-release, locking hooks that are reliable.
A trailer expands bike usefulness hugely. Commercial ones are good. For children, use a child trailer; for cargo, pick a flatbed. You will be able to shift far more than you can lift, eg, logs, tools, materials. This will save you using fuel for non-essential purposes, or will save a horse for heavy lifting jobs.
Modern puncture-resistant tires may seem expensive but are always worthwhile. Schwalbe Marathon Plus is the gold standard but cheaper Marathon is a good and common model.
Assemble some bike spares and tools: tires, inner tubes, chains, spokes, patch kits, spare nuts and bolts, spare pump. Chain-tool, crank tool, sprocket tool. Carry a repair kit or walk.
In a vehicle-based scenario, consider bicycles to be your life raft: not ideal, but better than swimming. If you work in a city, experience in London and Tokyo shows that everyone wants a bike as soon as transportation troubles become apparent. Shops sell out within hours of a “get back home” event.
Be realistic about budget. Bikes are safety critical and can be worked hard every day, so don’t underspend. If you live within 10 miles of work or shops, you can incorporate a bicycle into your life now, and get free fitness training whilst saving on gas. – M.W.