For the time being I will sell off my 27 speed road bicycle (aluminum frame and carbon fiber front fork), and keep my cheap inexpensive $128 dollar department store single speed bicycle with flip flop hub. I bought it for doing leisurely rides in town, and the occasional leisurely ride on bike paths. I purposely decided to get the simplest type of bicycle (single speed), because it has fewer parts to break or malfunction. There are no cheap derailleurs, no cheap suspensions, no cheap disc brakes, no carbon fiber to give me problems.

I have owned cheap department store bicycles before, sometimes they lasted many years with no problems, and sometimes they only lasted a few years before they started developing problems. Thankfully nothing dangerous or catastrophic happened. Just premature worn out parts, usually with the derailleurs and gearing. So I'm not expecting anything special from this department store single speed bicycle. I know what to expect.

Later in the future I might get an old vintage mountain bike from the 1980's or 1990's, and convert it to a inexpensive budget touring bicycle. Assuming I do that, I would definitely look for a high quality name brand mountain bike, with a steel frame - such as Chromoly 4130 or Reynolds 531 steel frame and fork. No suspensions to add weight and complexity. I would want standard 26 inch wheels and tires, because they are very easy to find anywhere in the world. And I would certainly replace the knobby tires with better tires. Something like Schwalbe Marathon road tires or similar. And replace any single wall or steel rims, with double wall aluminum rims with 36 spokes, for the added strength and stable braking power in the wet.

I know most vintage mountain bikes have 18 speeds (I had a few back in the day). If everything was in very good condition, I might keep it as is. But if the parts are worn out, I might just replace with more modern components (probably as 2x drivetrain). I might go with a 2x front chainring, with a 8 to 10 speed cassette in the back.

Of course if I wanted to go touring in poorer parts of the world someday, I know many bicycle tourists and bike packers use 2x or 3x chainring drivetrains with 8 or 9 cog cassettes, because these sizes have been the standard for many years. And thankfully the chains, shifters, and derailleurs, etc are usually more compatible with each other as well, and cheaper to purchase. These types of components can usually be found in pretty much every country around the world. Not so much the newer 1x chainring in the front, or 10,11 or 12 speed cassettes in the back. So perhaps I would build a inexpensive budget touring bike with a 2x chain ring and 8 or 9 speed cassette. And of course a good quality steel frame and fork, because it can be repaired anywhere in the world. But honestly I would probably do most of my riding here in the United States. And if I went overseas, it would be countries like Japan, Australia or Western Europe.

I would also add bar-ends on the handlebars, add fenders, a rack, better saddle, lights for nighttime riding, at least 2 water bottle cages, and large platform flat pedals.

If I had enough storage space and money, I would like to have a few bicycles in my collection, for different purposes. A simple single speed bicycle for causal leisurely riding in town. A high quality mountain bike from the 1980's to 1990's, converted into a budget touring bike. And a vintage 10 speed bicycle from the 1970's, when I want some extra speed and efficiency while riding. And a beat up looking vintage 3 speed sturmey-archer (or Shimano equivalent) internal hub bike for cargo and utility, like grocery shopping or commuting to work, when I don't want to deal with derailleurs. But in all cases, with steel frames and forks, no carbon fiber, no suspensions, nothing that would be a magnet for thieves.