Front derailers need to have all of their parts. Sometimes they break, but more often one or more small parts are missing. If the derailer has all of its parts, it's OK.
Front derailleurs are mostly very similar, and you only need to check one thing to sort them. Double or Triple?
One type of front derailleur is meant to be used on bikes with two chainrings in the front, and is called a "double" front derailleur. The other is used with bikes with three chainrings in the front, and is called a "triple". The only difference is that one side of the cage (the metal plates that push on the chain) is taller on a triple.
Desviadores Delanteros (m)
|Ball Bearings • Brakes (Caliper Brakes, Cantilever Brakes & Disc Brakes) • Brake Levers • Chainrings • Chains • Cranks|
|Derailers (Front & Rear) • Forks • Frame • Front Derailers • Handlebars • Hubs • Pedals • Quick Release|
|Rim • Seatposts • Seats • Shifters • Skewer • Spokes • Stems • Tires • Tubes • Wheels|