Bicycle Chain Link Tool: How to Use, Break, and Install Chains

How to use a chain link tool?

A chain link tool, also commonly known as a chain breaker, is an essential bicycle maintenance device designed to precisely remove or install pins in a bicycle chain, allowing for chain repair, replacement, or length adjustment.

Understanding the Chain Link Tool (or Chain Breaker)

A bicycle chain link tool is a specialized device used to manipulate the pins that hold chain links together. Its primary function is to push a chain pin out to "break" the chain or to push a new or existing pin back in to "join" the chain. Understanding its components and purpose is crucial for effective use.

• What it is: A compact, hand-held tool featuring a threaded handle, a pushing pin, and an anvil or cradle where the chain rests.
• Why it's used:
  • To shorten a new chain to fit a specific bicycle.
  • To remove a damaged section of an old chain.
  • To install a new chain.
  • To re-join a chain after a repair, though many modern chains now use master links for easier re-connection.
• Key Components:
  • Anvil/Cradle: The slot where the chain links are seated, providing support.
  • Pushing Pin (or Driver Pin): The small, hardened pin that extends from the screw mechanism to push against the chain pin.
  • Screw/Handle: The threaded mechanism that drives the pushing pin forward or backward.

Essential Safety Precautions

While using a chain link tool is generally straightforward, adhering to safety protocols is important to prevent injury and damage to your equipment.

• Eye Protection: Always wear safety glasses. Small metal fragments can dislodge during the process.
• Stable Workspace: Ensure your bicycle is securely mounted in a stand or that the chain is otherwise stable to prevent slips.
• Correct Tool Size: Verify that your chain link tool is compatible with your chain's width and pin size. Universal tools are common, but some chains (e.g., narrow 11- or 12-speed chains) may require specific tools.
• Cleanliness: Work on a clean chain and tool to prevent contamination and ensure smooth operation.

Step-by-Step Guide to Breaking a Chain

Breaking a chain involves carefully pushing one of its pins almost entirely out of the side plate, allowing the chain to separate.

1. Locate the Pin: Identify the specific pin you wish to remove. If shortening a new chain, choose a pin that will result in the correct length.
2. Position the Chain: Place the chain into the tool's anvil/cradle. Ensure the chain pin you intend to push out is perfectly aligned with the tool's pushing pin. The chain should sit snugly, with the pin centered.
3. Align the Tool Pin: Slowly turn the tool's handle clockwise until the pushing pin just makes contact with the chain pin. Double-check that the tool's pin is perfectly centered on the chain pin to prevent bending the tool's pin or damaging the chain link.
4. Turn the Handle: Continue to turn the handle clockwise slowly and steadily. You will feel resistance as the tool's pin begins to push the chain pin out of the outer plate. Keep turning until the chain pin is pushed almost all the way through the outer plate, but still captured by the inner plate. For most standard chains, you want to leave the pin slightly protruding from the inner side of the link.
5. Separate the Chain: Once the pin is sufficiently pushed, the chain will separate. Be careful not to push the pin all the way out if you intend to re-use the chain or the pin, as some chain pins are designed to remain partially attached for re-installation. For chains that use a replacement pin (often found with 9-speed and higher chains), it's fine to push the old pin completely out.

Step-by-Step Guide to Installing a Chain (or Rejoining Links)

Rejoining a chain involves pushing a pin back into place to connect two open chain ends. This can be done with the original pin (if it wasn't fully removed) or a new replacement pin.

1. Prepare the Links: Bring the two open ends of the chain together, aligning the outer plate of one end with the inner plate of the other. If using a new replacement pin, insert it through the aligned holes.
2. Position in Tool: Carefully place the joined (or nearly joined) chain section into the tool's anvil, ensuring the pin to be pushed is aligned with the tool's pushing pin.
3. Push the Pin Through: Turn the tool's handle clockwise, slowly pushing the pin until it is flush with the outer plates on both sides. Avoid pushing it too far, as this can damage the link.
4. Check for Stiffness: The newly joined link may be stiff. To loosen it, gently flex the link side-to-side. You might hear a small "pop" as it frees up. Repeat until the link moves as freely as the others. A stiff link can cause poor shifting performance.
5. Use a Master Link (Alternative): For many modern chains (especially 9-speed and above), a quick link or master link is provided or recommended for rejoining the chain. This method is often easier and provides a more reliable connection than re-using a pressed pin. If using a master link, simply connect the open ends of the chain with the master link according to its specific instructions.

Common Mistakes to Avoid

• Bending the Tool Pin: This usually happens by misaligning the tool's pin with the chain pin or by forcing the tool when there's excessive resistance. Ensure perfect alignment before applying significant force.
• Damaging Chain Links: Improper positioning or forcing the pin can deform the chain plates, leading to a weak or stiff link.
• Pushing Pin Too Far: If you intend to re-use an original pin, pushing it completely out can make re-installation difficult or impossible, depending on the chain type.
• Not Checking for Stiff Links: A stiff link will cause poor shifting and potential chain skip. Always flex the newly joined link to ensure it moves freely.
• Using the Wrong Pin: Do not re-use old pins on narrow (9-speed and above) chains that are designed for single-use replacement pins or master links.

Maintenance and Care of Your Tool

Proper care will extend the life of your chain link tool and ensure its reliable performance.

• Cleaning: After each use, wipe the tool clean of any grease or grime.
• Lubrication: Occasionally apply a light coat of lubricant (e.g., bike chain lube or light machine oil) to the screw thread and the pushing pin to ensure smooth operation.
• Storage: Store the tool in a dry place to prevent rust.

When to Seek Professional Help

While using a chain link tool is a fundamental skill for cyclists, there are situations where professional assistance is advisable.

• Uncertainty: If you are unsure about any step or encounter unexpected resistance, it's safer to consult a qualified bicycle mechanic.
• Complex Issues: If your chain exhibits damage beyond a simple break (e.g., bent links, stretched chain), a mechanic can assess whether repair or full replacement is necessary.
• Specialized Chains: Some high-end or unique chains may have specific breaking/joining procedures or require proprietary tools.
• Repeated Problems: If you frequently experience chain issues despite proper maintenance, a professional can diagnose underlying problems with your drivetrain components.