MWPdx

So I'm looking for an older cheap used bike for my "rain bike". I want it to be cheap but 'upgrade-able' in case some stuff is worn out or whatever. I don't know a whole lot about this stuff (hoping to learn a lot through taring this one apart and building it back up). I'm wondering if there's anything I should look for/avoid as far as being able to get new(ish) parts for it, repair it, etc.

johnny99

Plenty of upgrade issues:
1. French/Italian threading is not compatible with English/Japanese
2. 700C vs. 27" wheels
3. rear wheel dropout spacing
4. index shifting for different sized cassettes
5. Campy vs. Shimano and other compatibility issues
6. specialized/expensive/rare tools required to work on some components

And of course there the obvious things to look for in a used bike like abuse, crash damage, fitting, money required to get the bike working, etc.

If you don't know what really know what you're doing (or even if you do), upgrading a bike can be expensive and complicated and may not give you much benefit for the price.

TL179

See above. But if you want gears and a modicum of performance get a mid 80's race or sport bike with 6 or 7 speed shimano. I'm always impressed by the quality of 105 and exage components (6 or 7 speed) considering how cheaply you can get them. Even on the lowest exage group shift quality is snappy and precise. There are probably close to a hundred different brands that produced this type of bike and no matter where you live you can almost always get one for less than $200. As a plus many of these bikes can accomodate 32mm tires, and if its Shimano you can bet the 130bcd chainrings, 7 speed cassettes, and compatible rear dearaileurs will be easy to find.

Road Fan

Ok, there can be problems dealing with these issues, but most of what you'll find on the market is compatible with modern parts and tools, except for threaded versus whatever else headsets. Good threaded headsets that are installed right don't need much periodic help, anyway.

Same goes for rare/odd tools. Most of the things that are really hard to deal with are with French parts. Stronglight crank extractors are probably the biggest likely issue, but if you get any vintage bike with Shimano, SunTour, Campy, or modern cranksets, there aren't going to be any odd tool issues in that part of the bike. Cone wrenches are needed for all cup/cone hubs, but the wrench sizes are different brand to brand. Like headsets, good cup/cone hubs that are set up right don't usually need a lot of annual help. I personally think cottered cranks are a problem, but I thought that back in my 3-speed days.

If you have few decent old bikes in mind, ask over on the Classic and Vintage forum. People there have a lot of experience with the usual old stuff and the wierd old stuff. There are a lot of people setting up bikes that are usable today based on good used bikes that are as much as 50 years old. They can also help recommend frames that actually have room for fenders, if you're building a rain commuter.

There are also some friction setups that work so well you might not miss indexing, at least on rainy days.

BarracksSi

And people were wondering why anyone would pay for the new steel retro Allez:
https://www.bikeforums.net/road-cycling/575699-2010-steel-specialized-allez.html