National defense bicycles are collectible. National Defense brand bicycles are a type of bicycle produced by Qingdao Bicycle Factory (a public-private partnership Qingdao Bicycle Factory). They are divided into heavy-duty National Defense brand bicycles or ordinary National Defense brand bicycles. They are commonly known as "Big National Defense" and "Small National Defense". They have been produced since 1952. 980 heavy-duty national defense brand bicycles are small in number and very valuable for collection.