Breaking a chain is usually done to shorten it or remove it for cleaning
You break a bicycle chain to separate the links so you can remove it entirely, shorten it, or replace a damaged section. The method depends on whether your chain has a master link (a removable connector) or whether you need to push out a pin that holds the links together. Most modern chains have a master link, which makes the job straightforward. Older chains and some higher-end models require a chain tool to push the pin out.
Breaking a chain is not difficult, but doing it wrong can damage the links or leave you unable to reassemble it. The right approach takes five minutes and requires either a chain tool or just your hands, depending on your chain type.
Key Takeaways
- Master links (also called quick links) can be separated by hand or with pliers by squeezing the outer plates together, and they snap back on without tools.
- Chains without a master link need a chain tool to push out the pin that holds a link together, and the pin must be pushed out partway, not all the way through.
- A chain tool costs between $15 and $40 and is worth owning if you do your own maintenance, since you will use it repeatedly.
- After breaking the chain, count the links you remove so you know how many to add back if you reassemble it later.
Identifying whether your chain has a master link
Look at your chain closely. A master link is a single link that looks slightly different from the others — the outer plates are usually stamped with an X or a brand name, and the link sits perpendicular to the direction the chain runs. If you see one link that stands out, you have a master link.
If every link looks identical and they all run in the same direction, your chain does not have a master link. You will need a chain tool to break it. Most single-speed bikes, BMX bikes, and budget mountain bikes have master links. Many road bikes and higher-end chains do not.
Breaking a chain with a master link
Locate the master link on your chain. Flip your bike upside down so the chain hangs down, or shift the chain to the smallest chainring and smallest cog to create slack. This makes the link easier to reach.
Squeeze the outer plates of the master link together using your fingers, pliers, or a master link removal tool. The outer plates will compress inward, and the inner plates will separate. Once separated, the link pulls apart by hand. If you cannot squeeze it by hand, use pliers — grip the outer plates and squeeze firmly until you feel them give.
After you have removed links or cleaned the chain, reconnect the master link by sliding it back onto the chain ends. The link will snap into place with a click. You do not need tools to reconnect it — the spring tension in the outer plates holds it together. Some riders prefer to use a master link tool to may support it is seated correctly, but it is not required.
Breaking a chain without a master link using a chain tool
A chain tool (also called a chain breaker) is a small handheld device with a pin that pushes against your chain pin. You can buy one at any bike shop or online for $15 to $40. Park Tool and Shimano both make reliable models.
Place your chain in the tool's slot so the pin of the tool aligns with the pin of the chain link you want to break. Tighten the tool's handle slowly. The pin will push the chain pin out partway. Stop when the pin is almost all the way through — you want it loose enough to separate the links, but not so far out that it falls out completely. If the pin falls out entirely, you will have trouble reassembling the chain.
Once the pin is pushed out enough, remove the chain from the tool and pull the links apart by hand. If the link is still tight, use the tool again to push the pin out a bit more. After you have separated the chain, you can remove links or inspect the damaged section.
Removing links from your chain
Count the links you are removing before you take them off. Write the number down or take a photo so you remember how many to add back later. Most chains are shortened by removing two, four, or six links at a time, depending on how much slack you need to remove.
After you have broken the chain at the point where you want to remove links, separate the unwanted links and set them aside. Then reconnect the two ends of the chain using the method that matches your chain type — either by snapping the master link back on or by using the chain tool to push the pin back through the link.
Before you ride, shift through all the gears and spin the pedals backward to make sure the chain runs smoothly. A freshly shortened chain sometimes catches slightly on the derailleur until it settles in.
Reassembling the chain after breaking it
If you have a master link, slide the two chain ends into the master link and squeeze the outer plates until they snap into place. The link will hold firmly once seated. Spin the pedals backward a few times to make sure the link moves smoothly through the drivetrain.
If you used a chain tool to break the chain, you will need the tool again to reassemble it. Align the chain ends so the pin hole of one link faces the pin of the other. Place the chain in the tool and push the pin back through until it is flush with the outer plate on both sides. The link should move freely once the pin is fully seated. If it is stiff, back the tool off slightly and try again — the pin may be slightly misaligned.
When to replace the chain instead of breaking it
If your chain is rusted, kinked, or has stiff links that do not move smoothly, breaking it to clean or shorten it will not fix the problem. A damaged chain should be replaced entirely. A new chain costs $20 to $60 depending on the type and quality, and installation takes 10 minutes with a chain tool.
If you are breaking the chain to remove a single damaged link, measure the chain length before you remove the link. You may need to remove two links (one on each side of the damaged one) to keep the chain the correct length. After reassembly, the chain should have about half an inch of vertical play when you lift it at the midpoint between the chainring and the cog.
Frequently Asked Questions
Can I break a chain without a chain tool?
Yes, if your chain has a master link — you can separate it by hand or with pliers. If your chain does not have a master link, you need a chain tool to push the pin out. There is no safe way around this without the tool.
What happens if I push the pin all the way out?
The pin will fall out and you will lose it. You can still reassemble the chain by pushing a new pin through, but you will need a spare pin or a new master link. Most chain tools come with spare pins, or you can buy them separately for a few dollars.
How do I know if my chain is too long or too short?
Shift to the smallest chainring and smallest cog. Lift the chain at the midpoint between the two. It should move up and down about half an inch. If it sags more than that, it is too long. If it is tight and does not move, it is too short.
Do I need to clean the chain after breaking it?
Breaking the chain gives you a good opportunity to clean it, but it is not required. If you do clean it, use a degreaser and an old toothbrush, then dry it completely before reassembling. A clean chain runs quieter and lasts longer.