Chain tool
| Classification | Bicycle tools |
|---|
A chain tool is a small mechanical device used to disassemble and reassemble a bicycle chain. It is primarily used to push out and reinsert chain pins (rivets), allowing a chain to be "broken" for removal, repair, or replacement, and then rejoined. Chain tools are also commonly used to resize a bicycle chain by removing the excess links to achieve the correct chain length for a specific bicycle setup.
A bicycle chain consists of interlinked outer and inner plates held together by pins. The chain tool applies controlled force via a threaded screw to gradually push these pins out of, or back into, the chain links, depending upon the intention of the user.
The chain tool has two positions where a chain can be inserted perpendicular to the tool, one close to the movable screw portion, and one lower down just above the fixed end. In each position, there are a pair of protruding tabs; one fits into the center of one link of the chain, the other fits into the center of the next link. With the chain properly in place, the pin is held in the center of the tool, so that the tip of the movable screw can press on the end of the pin. The end of the screw is slightly narrower than the pin, so that it can press the pin through the link. The end of the screw is often a removable piece which can be replaced when worn.