Nice find.
Check the wear on the teeth. A sharks fin shape is typical of worn out rings and may make chain throwoff easier. Other factors inc bent out of alignment, or just badly adjusted front and rear derailleur mechs
Components that wear and need occasional replacement inc
Chain
Rear sprockets
Front chainrings
Cable inners
Cable outers
Brake blocks
Tyres
Just replace as and when needed
Check the wear on the teeth. A sharks fin shape is typical of worn out rings and may make chain throwoff easier. Other factors inc bent out of alignment, or just badly adjusted front and rear derailleur mechs
Components that wear and need occasional replacement inc
Chain
Rear sprockets
Front chainrings
Cable inners
Cable outers
Brake blocks
Tyres
Just replace as and when needed