>>1008030This is a completely great idea OP and you should absolutely definitely do it. I have done this with my brother in Ecuador and Mexico and he has also done it a few times in SE Asia and southern Africa.
Two good ways to do it as i see it: bring your own decent but not too nice bicycle or buy a complete piece of shit when you get there. It depends on your taste. I don't really want to ride on a shitty chinese disposable bike so when i've done it i brought my late 90s Trek mtb. This is good because you get to ride your own bike and it's a nice bike but there are several drawbacks: forget finding parts in most places; you have to worry about it getting stolen in addition to breaking; you have to get it where you're going. So if you're really wedded to riding your own bike, or, perhaps if riding a junker will significantly hinder your enjoyment of your trip, bring your own. Also, if you're really heading someplace very rural it may just be a bad idea, whereas when i was in Mexico i knew i could cobble together parts and stuff if i really had to. If you're bicycling across Namibia, not so much.
There are lots of advantages of buying a shitty local crapcycle when you arrive. It will probably be pretty cheap; you don't have to give two shits about it, and it can be fixed or just ditched if unsalvagable. my bro has some funny stories about having his shitty chinese bike fixed by a local mechanic sitting under a tree with like a rock and some sticks (not joking) when he was in, i think, Tanzania.
i wouldn't go the middle route and try to find a decent bike when you arrive to your destination. seems like the worst of both worlds.
most of all--have fun, be safe, smile at people, give in to being a moron outsider and be able to laugh at yourself, be open, be curious. bon voyage!