There's a whole subculture around restoring and modifying 90s mountain bikes. See for example the XBiking subreddit. Steel frame, rigid (no suspension), 26X2"

There's a whole subculture around restoring and modifying 90s mountain bikes. See for example the XBiking subreddit. Steel frame, rigid (no suspension), 26X2" wheels/tires, rim brakes, threaded bottom brackets, etc. makes a great platform for an all around bike used for commuting, exercise, on road and off, pretty much anything except road racing or downhill racing at MTB parks. You can absolutely find parts for these bikes everywhere. Stay away from suspension, brifters, (hydraulic) disc brakes, and wireless shifters as these are the ares where there is constant obsolescence and older parts are impossible to find.