the project. take a classic road bike bought at a garage sale for $85, bring it up to working order, use that bike to complete your first century bike ride (100 miles). for extra fun, keep the bike as classic as possible, and do the century on gravel that requires a lot of climbing.
explanation. I have been of the mindset that you can do lots of things on bikes. i do not like the idea that you need a special specific thing. the thing i do not like about bike riding is the hierarchy. the focus on gear. i come from a running background, where, sure you have people that skip practice and eat poorly and perform, but those people do not last. the ones that come back year after year put in the work. and there is no way around it. you cannot buy better gear and get faster. that is what i do not like about biking, that you can buy better stuff and get faster.
I also do not think it is true. i think at a certain level, for certain things, people just have to be better or faster to be better or faster, so I understand that.
so this project is just reaffirming the theory that you do not need special gear, and putting the focus back on doing the work.
old bikes have a few things to consider
the parts are cheaper. the hard part is finding them, so you need to find a good bike shop, or figure it out yourself. every bike shop should have one person that is a good mechanic. if they do not, you need to find a new bike shop. i have seen good mechanics even at pawn shops and second hand sporting goods stores, i've seen them at walmart even.
they were likely built to be repaired. the most common example i can think of is the bottom bracket or headset. in old quill and stem, bikes, you can buy $2 worth of bearings and some grease and have a new functioning headset or bottom bracket. in a new bike, you're looking at a $40 part that needs even more specialized equipment to put in and take out. when it comes to function, i think most people are not limited by the type of headset or bottom bracket they are running.
the geometries are not as dialed, so they are more all-arounders. there was a move to get things specialized, but it is nice to have a more comfortable frame, that can take larger tires, and has mounts for racks. they are coming back, but now called gravel bikes or adventure bikes, as if touring bikes did not exist, or just 'bikes' before mountain and race bikes came around.
you can leave them. even if they have a high emotional value, they are often not as much of a target for financial flipping stealing. so ride it to the bar and lock it up nice, but you don't have to be worried about it getting a scratch or whatever.
Bikes built in the 70s were good, some in the 80s, 90s were a crapshoot. Look for good quality steel if you're looking at an older bike. You are also upcycling which is nice. And they are a good chance to learn new skills.