A conventional chain includes chain plates, rollers, bushes and chain pins. Generally, the components of the conventional chain are assembled in the factory, and are difficult to be reassembled by an end-user. For example, two end portions of each of the chain pins are riveted by a riveting machine in the factory for holding two corresponding pairs of chain plates together. It is difficult for the end-user to reassemble the chain pins and the chain plates without the riveting machine.
Referring to FIG. 16, a link unit 7 of another conventional chain includes two chain plates 71 and two chain pins 72. Each of the chain plates 71 has a circular through hole 711, and a connecting hole 712 that is spaced apart from the through hole 711. Each of the chain pins 72 has opposite first and second end portions 721, 722. The first end portion 721 of each of the chain pins 72 is inserted through the through hole 711 of a respective one of the chain plates 71 and riveted to the respective one of the chain plates 71 in advance. To assemble the link unit 7 of the conventional chain, an end user needs to simultaneously and respectively aligned the chain pins 72 with the connecting holes 712 of the chain plates 71 in order to engage the second end portion 722 of each of the chain pins 72 with the connecting hole 712 of the other one of the chain plates 71. In addition to the laborious assembling operation, the chain plates 71 of the link unit 7 of the conventional chain are easy to be moved relative to each other accidentally, so as to unwantedly disassemble the link unit 7.