Sooner or later, all bike enthusiasts will see their bike chain relax or break … Fortunately, you don't have to take it to an expensive store for this kind of problem if you know what to do. yourself.
Method 1 of 2: Replace a chain that has come undone
Step 1. Find the offset
Sometimes, while you are riding a bike, the chain can slip out of its location without breaking. In this kind of case, it always goes through the front and rear derailleurs and there is no special maintenance to do, you just need to put it back on the cogwheels. When it comes undone, get off the bike and observe the mechanism. Usually it falls off the front sprocket, but it remains engaged in both derailleurs.
Observe if the chain got stuck against the frame, you must release it before you can get back on the bike
Step 2. Quickly unpin it
Sometimes, if the chain has come undone, it will get stuck between the rear sprocket and the frame. In this case, you should relax it at the rear wheel and undo the bolt to free the wheel from the chain a little. Once you've relaxed her enough, just pull her out.
- Activate the quick-release mechanism by pulling the small lever in the center of the rear wheel. Then unscrew the bolt on the other side to release the pressure that the rear wheel puts on the frame. Once you've unscrewed it, the chain should come out easily.
- Remember to re-tighten the quick-release mechanism before getting back in the saddle. You should be able to close it completely, it should be tight, but not too tight to push all the way down. If it looks tight, loosen the bolt a bit and try again. Likewise, if it is very relaxed, you need to tighten the screw.
Step 3. Loosen the chain on a rear derailleur
If you have a bike with a rear derailleur, just relax it and wrap it around the front sprocket. On most bikes, it's spring loaded to keep the chain tight as you pedal. Take advantage of this fact by pushing the rear derailleur arm forward to relax it. Then use the slack to pass the other side of the links around the smaller front sprocket. Release your arm and make sure the chain is tight.
From there, you can get back in the saddle! Your bike may feel unstable until the chain snaps back into place on the various sprockets
Step 4. Turn the pedals if there is no derailleur
If your bike does not have one, put the chain back in place by turning the pedals. Many models do not have one. The quickest way to fix them if it has fallen out is to pass it back over the rear sprocket, snap it over the bottom of the front sprocket while gently rotating the pedals forward. It should snap back onto the gears and begin to rotate around the front sprocket. Once the part you snap into is on top of the front sprocket, the chain should start to wrap around the sprockets as before.
It will also be easier to turn them if you raise the rear wheel. You can do this by putting it on a stand or raising the rear wheel with whatever material you have on hand. Alternatively, you can find someone to help lift the wheel off the ground while you put the chain back in place. Otherwise, it is also possible to put the bike upside down
Step 5. Gently pedal forward with the correct speed
Get into the saddle and slowly pedal forward. If your bike has gears, the chain could snap back to the one it was in before it slipped. Otherwise, you should keep changing them until the bike is moving well.
Be aware that on bikes with gears, it can be dangerous to see the chain fall and this often indicates that the chain is too slack. Consider adjusting his tension before setting off again
Step 6. Perform some checks
Before you can get back in the saddle, you must make sure you have engaged a suitable gear. If your bike has them, you should shift the front and rear derailleur gears until the chain turns smoothly and quietly.
Method 2 of 2: Replace a broken or completely fallen chain
Step 1. Get a new channel
To be able to repair it if it is broken or if it has fallen completely, you will need a new one adapted to your model and a chain guide to dismantle the old one and install the new one. You will also need a spare link to close the new chain, but it should be delivered to you at the same time as the new chain.
You can buy the equipment you need at most sports or bicycle stores
Step 2. Assess the damage and repair asap
Stop and lay the bike on its side with the gears in the air. If the chain is still on the bike, observe it to see if it is broken. If you see it hanging off the derailleur, it will be easy for you to find both ends of it. If it has fallen off completely, you can just start to climb a new one. On most models, the links are connected to the next by passing a metal rod through the flat side of the outside of one link and the inside hole of the next link. Most bicycle chains are classified into three categories.
- Chains with special replacement links: you need a special rod obtained from the manufacturer (which is usually included when you purchase the chain) to repair it. If you don't keep them with you when you go out, you're going to have few repair options until you can go to a repair store.
- The chains with master links: they have special links with two rods used to join the two ends. If a link breaks, you will have to wait until you can replace it before you can repair it.
- Chains with normal shanks: These older models have uniform shanks that you can use to repair a broken one (if you have the chain fin with you).
Step 3. Take out the broken chain
If you've decided that replacing it is going to be easier than repairing it, the first thing to do is get rid of the old one. If it is completely broken, just turn the pedals until it comes out of the gears and you can simply pull it out. If it is still a single piece, you should open it in a place so that it is easier to pull it out. You can do this with a chain drift.
- If you are using a standard one, it suffices to align one of the links with the internal notch of the tool, to make it hold on the "teeth" present before turning the handle to bring the point down and push the rod out of the chain. If you want to use it again, you need to make sure you push the rod just enough so that the two links are separated. Do not take it out completely, as it will be very difficult to put back in place.
- Once you have opened the chain, simply spin the pedals to release it from the sprockets. The ideal would be to buy a replacement the same length as the one you had, although bikes with a rear derailleur allow some room for error. This is the right time to count the links on your chain. You should also take into account the transmission system, as it will help you choose a well suited one. For example, a nine-speed transmission must be fitted with a nine-speed chain, etc.
Step 4. Raise the rear wheel
Then pass the new chain through the rear derailleur. You will have to turn it around, which will be much easier if it is not on the ground. If you have a bike rack or a wall hook in the garage that allows you to hang the bike with the sprockets facing you, use that. Otherwise, you can simply raise it up by placing it on a wooden frame, boxes, blocks or whatever material you have available.
You should also note the organization of the derailleur. If the rear derailleur has a cable connected to the chainring change mechanism, switch to the higher chainring. If the front derailleur has a cable, you should switch to the lowest chainring
Step 5. Pass the chain through the rear derailleur
It is a spring-mounted sprocket system that hangs below the rear main sprocket on most modern bicycles. It is essential to pass the chain correctly in the derailleur in order to be able to pedal without any problem. Take the "female" part of the adapted chain (the one where there is no sticking out rod) and pass it around the lower pulley before making it go up on the upper pulley. If you do it right, it should describe a nice S through the various gears. Make sure it is not blocked or resting on anything other than the pulleys. If so, you should see a bump on your S.
- There may be a small metal tab between the two derailleur pulleys. The chain must pass through this tab without touching it.
- Some bikes do not have a derailleur like models with fixed gears or with another shifting mechanism. In this case, all you have to do is pass the chain through the rear sprocket as shown in the previous step, turning the wheel if necessary.
Step 6. Pass the chain through the rear cassette
On bikes with gears, the cassette is simply the assembly of chainrings attached to the rear wheel of the bicycle. After threading it correctly through the derailleur, pull it out and pass it over the smaller chainring of the cassette. Make sure it's tight and threaded through the rear derailleur and sprocket, then pull it up to give it a little slack on the other side.
Step 7. Pass it through the front derailleur
Most modern speed bikes have a metal mechanism near the front sprocket that allows the chain to be shifted from chainring to chainring. Pass the end through the front derailleur while rotating the rear wheel to give yourself some slack.
Again, some models are not equipped with this mechanism, in which case you simply have to pass the chain through the front sprocket as explained in the next step
Step 8. Pass the chain through the front sprocket
Align it with the smaller sprocket. Tighten it so that it engages snugly with the teeth of the front sprocket, then pull it to wrap it all around, rotating the pedals if necessary to give you some slack.
Step 9. Connect both ends of the chain
Finally, once it is in place all around the pinion system, you can connect the two ends and get back in the saddle. Line up the "male" and "female" ends with the chain fin (which you can buy at most bicycle stores). Make sure that the two ends of the chain are threaded well over the notch of the tool between the "teeth". Turn the handle to thread it onto the gears, connecting the two links. Make sure the rod protrudes the same length on both sides of the link, as a small offset could cause a structural problem and you will soon have to start your repairs again.
You can use a small C-shaped hook to hold the two ends together while you install the rod. It will make your job easier and you won't have to worry about the position of the chain while you are pulling it up. If you don't have one, you might as well do it with a paperclip
- Knowing how to repair a bicycle chain is always very important. This will save you the cost of professional services for basic repairs, and you will avoid the risk of being left on your own far from a repair store.
- If you can, buy a tool designed to tighten the chain. Buy a pair and follow the instructions on the package. Usually you will need a small flathead screwdriver or an Allen key of a certain size. It is a very good tool to tighten it.
- If you find that she is relaxed and you cannot make it to the store now, you should take some links apart to make her shorter. However, you should only do this if you know what you are doing!
- If the chain does drop every now and then, it doesn't mean there is a problem with your bike, it can only mean you should have it professionally examined to see what's going on.
- Tie up your long hair, hanging clothes and zippers before doing any repairs on your bike that include the chain!
- Be careful not to put your fingers in it or you could injure your fingers or even cut one!
- If possible, you should wear gloves, as you could get grease on your hands.