There are few things to look for and it all depends on what bike you want.
-
derailleurs and shifters: With friction shifting you can slap any derailleur on bike and it will work. Otherwise look at the brand, model and number of speeds, they can have different cable pull standard that isn’t in production.
-
bottom bracket: It is mess of different standards but it shouldn’t be problem sourcing replacements.
-
frame: Good steel frame will outlive all the other components, so look at the mounting points for them. Flat mount disc brakes or type of V brakes, BB diameter and type,…
-
fork: Go for rigid fork if you want less things to worry about.
Basically look for all the parts, how to buy them, change them, if they require special tools…
Year ago local restaurant was raided for dealing weed. Not exactly for selling it there the owner was just also running this restaurant.
Whole family was in it so newspaper run story “Even granny watered the plants”