What You Need Before You Start
Changing a bicycle chain requires a chain tool (also called a chain breaker), a new chain that matches your bike's speed system, and a way to hold the bike steady. A bike stand is helpful but not required—you can flip the bike upside down so the handlebars and seat rest on the ground. You will also want a rag or old towel, since chain oil gets on your hands.
Before you buy a new chain, write down your bike's speed count. Look at the cassette (the metal rings on the back wheel) and count how many rings you see. Common counts are 7, 8, 9, 10, 11, or 12 speeds. A 10-speed chain will not work on an 11-speed bike, so this number matters. If you are not sure, take a photo of the cassette to the bike shop and they will match it for you.
The chain tool is the one tool you cannot skip. A basic chain tool costs $15 to $30 and works on almost any chain. If you do not own one, borrow from a friend or visit a local bike shop—many will let you use theirs for free or a small fee.
Key Takeaways
- A chain tool is required to remove the old chain; you cannot do this step by hand or with pliers.
- Your new chain must match your bike's speed count (7-speed, 10-speed, 11-speed, etc.) or it will not shift properly.
- The entire job takes 20 to 30 minutes the first time and becomes faster with practice.
- The hardest part is threading the new chain through the derailleurs correctly; take a photo of the old chain path before you remove it.
Remove the Old Chain Using the Chain Tool
Position your bike so you can see the chain clearly. Use the chain tool to push the pin out of one link. Place the chain tool on a link (any link will do), align the tool's pin with the chain's pin, and turn the handle clockwise. Push slowly—you only need to push the pin out far enough that the link separates, not all the way through. Stop when the pin is about halfway out; if you push it all the way, it becomes hard to reuse.
Once the pin is pushed out, wiggle the chain apart by hand. The chain will now be two separate pieces. Remove the old chain completely and set it aside. Wipe your hands on the rag because the next steps are cleaner.
Before you touch the new chain, take a close-up photo of how the old chain threaded through the front derailleur (the cage on the crankset) and the rear derailleur (the cage near the back wheel). This photo will be your guide when you thread the new chain. Many people forget this step and have to figure out the path by trial and error.
Prepare the New Chain to the Right Length
Lay the new chain out straight on a clean surface. Count the links on the old chain and count the same number on the new chain. Mark that link with a pen or tape so you know where to cut. Most new chains come longer than you need, and you will remove extra links to match the old chain's length.
Use the chain tool again to push the pin out of the link you marked. Push the pin all the way through this time so the link separates completely. You now have a chain that is the same length as the old one. Set the removed links aside in case you need them later.
Before you install the chain, lay it out next to the old chain one more time and count the links on both. They should match. If the new chain is still too long or too short, remove or add links now. It is much easier to adjust the length before installation than after.
Thread the New Chain Through the Derailleurs
This is the step that trips up most first-timers. Look at your photo of the old chain path. The chain must go through the front derailleur cage first, then down to the rear derailleur cage, then around the cassette (the rings on the back wheel). If you thread it wrong, the chain will not shift smoothly or will fall off.
Start at the crankset (the rings at the pedals). Pull the chain up and forward through the front derailleur cage so the chain sits between the two metal plates. Then pull the chain back and down toward the rear wheel. Thread it through the rear derailleur cage the same way—between the two plates. Finally, wrap the chain around the smallest ring on the cassette (the ring closest to the wheel rim) and bring it back up to meet the other end of the chain.
Do not connect the chain yet. Shift the front derailleur to the smallest ring and the rear derailleur to the largest ring (the one closest to the spokes). This gives you the most slack and makes connecting the chain easier. Pedal backward by hand to check that the chain moves smoothly through both derailleurs without rubbing. If it rubs, stop and rethread it.
Connect the Chain and Check Your Work
Bring the two ends of the chain together. They should meet with just a tiny bit of slack—you should be able to lift the chain about half an inch off the smallest chainring. If there is too much slack, you cut the chain too short. If there is no slack at all, you cut it too long. Most people get this right on the first try, but if you did not, you can add or remove one link and try again.
Use the chain tool to push a new pin through the link that connects the two ends. Push the pin until it clicks or until it is flush with the chain. The pin should stick out equally on both sides. If one side is longer, use the chain tool to tap it gently until it is even. Wiggle the connected link by hand—it should move as freely as the rest of the chain. If it feels stiff, the pin is in too far.
Spin the pedals backward slowly and watch the chain move through both derailleurs. It should move smoothly without rubbing or making noise. Shift through all the gears on the rear cassette, then shift the front derailleur. The chain should move cleanly from ring to ring. If it struggles or makes noise, the chain may be threaded wrong or the derailleurs may need adjustment—that is a separate job, but at least you will know the chain installation itself is done.
Common Mistakes and How to Avoid Them
The most common mistake is threading the chain on the wrong side of the derailleur cage. If the chain rubs against the cage when you pedal, you threaded it backward. Stop, unthread it, and try again with the chain going between the two plates, not around the outside.
The second mistake is pushing the connecting pin all the way through on the first try. If you do this, the pin falls out and you have to start over. Push slowly and stop when the pin is halfway out. You can always push it further, but you cannot pull it back.
The third mistake is forgetting to take a photo of the old chain path. If you do not know how the chain threaded through the derailleurs, you will waste 10 minutes figuring it out. Take the photo before you remove the old chain.
Finally, do not skip the length check. A chain that is too long will sag and fall off. A chain that is too short will not reach around the cassette. Lay both chains side by side and count the links before you connect anything.
When to Replace Your Chain
A chain usually lasts 1,500 to 3,000 miles depending on how often you ride and how well you clean it. Signs that your chain needs replacing include skipping (the chain slips on the rings when you pedal hard), rust or stiff links, or visible wear on the teeth of the chainrings. If the chain skips on a new cassette, the old chain is worn out and needs to be replaced.
Replacing a chain before it is completely worn saves your cassette and chainrings from damage. A worn chain will grind down the teeth on these parts, and replacing them costs much more than replacing a chain. If you ride regularly, check your chain every few months by looking for rust, dirt buildup, or stiff links that do not bend smoothly.
Frequently Asked Questions
Can I reuse the old chain pin or do I need a new one?
You need a new pin. Old pins are usually damaged when you push them out and will not hold the chain together reliably. Most chain tools come with spare pins, or you can buy a pack of 10 for a few dollars. Never reuse an old pin on a new chain.
What if the chain is still too long after I remove links?
Remove one more link and check the fit again. The chain should have just enough slack that you can lift it about half an inch off the smallest chainring when the derailleurs are in their loosest position. If you remove too many links, you can add one back by connecting a spare link with a new pin.
Do I need to clean the new chain before I install it?
New chains come with a light coating of oil to prevent rust during shipping. You do not need to clean this off before installation. After you ride for the first time, wipe the chain with a rag and explore fresh chain lube if it looks dry. This keeps it running smoothly and extends its life.
Why does my chain rub against the derailleur cage after I install it?
The chain is probably threaded on the wrong side of the derailleur cage. Stop pedaling, unthread the chain, and pull it between the two metal plates instead of around the outside. If it still rubs after you rethread it, the derailleur may need adjustment, but that is a separate repair.
How tight should the connecting pin be?
The pin should be pushed in until it is flush with the chain on both sides. The connected link should move as freely as every other link on the chain. If the link feels stiff or does not bend, the pin is in too far and you need to back it out slightly using the chain tool.