Echo the other Darth though it's my own bike and I'm not a shop mechanic, I've done almost all the things he just said to my 2001 vintage MTB which cost about $400 back then and it's still going strong. The crankset got replaced for chain suck; the chain and FD because they got bent in the chain suck incident; the cassette for gearing with the new crank; the BB at the same time because it needed a different spindle length. All parts were slight upgrades from original but not fancy. I moved the original EZ-Fire shifters to my tandem for some reason I forget but they still work ok and I replaced them with equivalent units. It did get a nice fork upgrade and I buy nice tires for it.