If you have a tool known as a chain wrench, repairing a broken bicycle chain will be a breeze. You can do most of the routine maintenance yourself. However, keep in mind that it is best to get a new replacement shortly after repairing a broken chain.
Method 1 of 2: Repair the Chain Without a Replacement Link
Step 1. Avoid shifting gears while the chain is broken
Although it may be easier to repair or replace the chain while the bike is in a lower gear, you should only change gears while pedaling. Shifting gears with a broken chain can lead to more problems.
Step 2. Use a wrench to carefully push the pin to the middle of the broken link
The chain wrench, which looks like a medieval torture device, is really easy to use. Each link in the chain has 2 round pins that connect it to the other links. Find the broken link and look at the pin that holds it to the rest of the chain. Slowly turn the wrench so that the bar pushes the pin out of the link halfway. Avoid pushing it all the way.
Step 3. Remove the broken link from the pin and discard it
You should do this while keeping the pin on the chain. This pin will be attached to the open link on the other side of the chain to put everything back together.
You can replace this pin with a new one, if you have one on hand
Step 4. Fit the 2 ends of the chain together so the holes line up
The link with the pin should be facing out so that you can push it through the 4 holes (2 in each link) and complete the chain.
To align the holes, you need to place the inner plates on the outer plates of the chain
Step 5. Use the wrench backwards to push in the pin and complete the link
After threading in the tool to remove the link pin, you need to screw it in to push it in. Work slowly, keeping your hand on the links to make sure everything is aligned.
Step 6. Loosen the connection to avoid clamping
Take the chain on each side of the newly attached links and wiggle it back and forth to loosen the new link. It may also help to move the key to the other side of the freshly made joint, and push the pin very lightly to release the 2 outer link plates from the center section, which will prevent it from jamming.
Step 7. Lubricate the chain with bicycle oil
Avoid using WD-40 lubricant or any other product that is not formulated for bicycle chains. Turn the bike upside down and pedal with one hand, dripping small amounts of oil onto the chain with the other. About 10-15 drops should be enough. Then use a damp cloth and tap the chain to remove any excess oil. If you run a finger down the chain, it should be slippery, but not covered with a puddle of oil.
Step 8. Avoid using the largest gear on the rear gears, as the chain is now too short a link
Most of the time the bike won't even allow you to get into these gears as the chain is not long enough for you to reach. However, the stress of trying to hit these larger sprockets can cause another breakage if you're not careful.
- Try to keep the chain straight between the front and rear gears. Don't let it stretch diagonally through the gears by being to the right on the front gears and at the same time to the left on the rear gears.
- Usually this chain repair is temporary, so you should add a new link or get a new chain soon after.
Method 2 of 2: Add a New Link
Step 1. Add a new link as soon as possible to bring the chain back to its normal length
If the chain breaks, you can remove the broken link and reconnect it as a temporary repair. However, the shorter chain will not be able to fit all gears, severely limiting your range. However, you can find new links at any bike store and at many sports retailers.
- It is not ideal to use a chain that has links with different levels of wear. The best thing to do is replace the entire chain instead of adding a new link.
- The main links are made to fit easily on a bicycle. Plus, they are easy to install quickly, making them convenient to store in your seat bag on long trips. These are by far the most commonly used links in home mechanics. You can check with a local bike store to find a chain that works for your bike.
Step 2. Point the main link in the correct direction
Most links have an arrow that should point in the direction of the chain when pedaling. The others are concave (bent inward) on one side, and this side should point toward the wheel and the rest of the bike.
Step 3. Squeeze the links to disengage the 2 halves of the main link
You'll notice that the main link has a figure-of-eight space for the pins, rather than the normal round pins and holes for the rest of the chain. If the chain is not yet unlocked, you need to take care of that now.
Some main links come in 2 asymmetrical halves: a C-piece with both pins and an outer plate. To repair these chains, you simply need to thread the C-shaped pin into the two open holes of the broken chain and then place the plate over the top
Step 4. Take each half and thread it into the hole on opposite ends of the chain
Each of the pins in the two halves of the main link should be located at one end of the chain. Make sure the pins also enter from opposite sides of the chain. You are going to reattach the chain using the number eight hole, and the pins need to be aligned.
Step 5. Connect the exposed pins through the number eight holes on the opposite links
First, put the chain together. Then line up the holes and thread the pins. However, you should keep in mind that this connection will now be very loose.
Some mechanics use a tensioner, a simple C-shaped cable that hooks into the grooves of the chain, to keep the chain taut as you connect it. Although not necessary, a pair of hands or a similar tool to hold the chain tightly together can make your job easier
Step 6. Use pliers to join the main link, snapping the pins into place
The goal is to force the pins on the other sides of the number eight hole to lock them in place. If you don't have a pliers handy, there is a trick to adjusting everything. Turn the bike upside down. Holding the rear brake down, slowly pedal the bike. As the brake holds the wheel, and therefore the chain, in place, pedaling pressure will pull the other side, adjusting the main link.
Step 7. Keep in mind that, after all, a broken chain often means you need a replacement
Although you can repair the chain in a number of ways, as noted above, it is usually necessary to replace a broken chain. Beyond breaking, old chains expand as the pins on the inside wear out. This may not sound like too much in theory, but it is important when driving. The chain handles and transfers all the force from your feet to the wheels, so a loose chain means you're going to push yourself harder for a lot less speed.
- The chain pins are specific to the number of speeds the cassette has. If you have any questions about this, you can check with a local bike shop.
- Always keep the old chain or the extra links from a new spare. However, remember that there are several types of chains designed to fit specific blocks, and one may not be compatible with another.
- The chain wrench is a tool that justifies its value, since chains often break for no apparent reason. Keep it with you when you ride the bike, as it could also help you help another stranded rider.
- Follow these instructions carefully and carefully. Don't rush any procedure.
- If you are really confused, you can ask a professional
- You should replace the pin you pushed in with a new one, as reusing the old pin could lead to failure. You can find replacement pins at your local bike store.