Originally Posted by Cdst

For someone looking to buy a quality, maintainable used road bike, how old is too old? I know this question won’t have an exact answer but I’d like some opinions. I have a mountain bike background and the standards have been changing so fast a bike more than about 5-7 years old is at risk of losing support. The best parts are no longer made for 26” wheels, non-boost hubs, straight steerers, quick release dropouts, and HG free hubs.

so maybe this question isn’t so much about age in years, but rather what standards might be dead or dying that would be found on a 5 or 10 year old bike. Some more context here: I am actually looking for a mechanical drivetrain and rim brakes. I expect high quality (think 105 or better) replacements will still be available for the next 10 years or so for those parts.
But Would older bikes typically limit me to under 28mm wide tires? Is there a year that carbon frames got drastically better and I should avoid something before that? What else should I look out for?