For the keen on speed, cyclists would love to invest in a good set of gears for their bike, which derailleur is a part of which. The derailleurs and chains play an essential role in the bike’s performance, but they can come undone and stop your ride at any moment.
It is a common thing for the old, worn-out chains to sneakily slip off your derailleurs in the middle of nowhere, so frustrating, right? But you should not drag your bike to the garage whenever the chains fall off – you can learn how to put the bike chain back on the derailleur with just your bare hands in a few minutes.
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Why Your Bicycle Chains Fall Off From The Derailleur?
The reasons for slipping bicycle chains off the derailleurs are numerous. All the bikes, regardless of BMX bikes or cruiser bikes, can face the same problem. For beginners and amateur cyclists, the wrong way of shifting gears can lead to out-of-derailleur bike chains in the long term.
Moreover, after long miles on the roads, it is highly likely that the chains are worn out and don’t move as well as the new ones anymore. For bikes, especially BMX bikes, when you modify the gears, mistakes can happen. Too long chains or improper adjustment on the gears can cause the chain to slip off at some points.
Too short a bike chain will result in the wrong tension needed for the wheel to spin and cause difficulty when shifting with the derailleur. A longer chain than required will be too loose to hang on the gears properly; thus, slipping off is unavoidable.
The Relationship Between Bike Chain And Derailleur
First, we should have knowledge of how bike chains and derailleurs work. There are two types of the derailleur, the front derailleur and back derailleur, or rear derailleur. However, the most related one to the bike chain is the rear derailleur.
The bike chain and derailleur are designed as corresponding parallel parts; the arms of the derailleur will be screwed in the frame and control the chain. The rear derailleur’s alignment with the sprockets pushes the wheels to move when the paddles circle.
That’s the basic relationship between a bike chain and derailleur. However, the bike chain and derailleur function are far more than that.
The structure of the bike chain is quite simple, consisting of links, rollers, plates, and pins. The chains are the parts that link the gears in the head and end of the bikes, more specifically, the two derailleurs. Thanks to the chains, the power is transferred from the pedals to the derailleur and moves the bike.
The bike chain moves in horizontal in front derailleurs and goes vertically and horizontally in the back derailleur. Therefore, the chances of a slipped bike chain in the rear derailleur are higher.
The rear derailleurs lay at the back of the gears, which help maintain the chain’s tension and shift. They are mounted to the center of the bike wheel, and together with the sprockets, they shift the chain from side to side the change gears, thus also changing the bike’s power transfer.
Meanwhile, the front derailleur is installed closer to the pedals and on the bike frame near the outer part of the back wheels. This type of derailleurs only exists on bikes with multiple chainrings. The movement of shifting gears of the front derailleur is quite the same as the rear one.
Chain – Derailleur Diagram
With all this information, you must have understood how bike chains – derailleur function, but how they work as a full gear and the mechanism behind them is another thing. Let’s get the explanation with this chain derailleur diagram:
The components to make up a gear set on bikes include rear derailleur, front derailleur, cassette, chain, and chain wheel. Each of them has its function, but they transfer and change the riding power of a bike as a whole.
As can be seen from the diagram, the rear derailleur works to move around and make sure that the tension is well delivered by the chain. Rear derailleur deals with all the slack, no matter which sprockets the chains are in.
Let’s have a closer look at the back part of the bike gears:
How the rear derailleur works with chains rely on the cables and pulleys. The upper gives direction for the chain to fall right on the sprocket. Meanwhile, the lower pulley will create tension for the lower parts of the chains.
When they are pulled and released for the cables, the derailleur will move in the opposite direction to the release. This mechanism often requires a cage and linkage to work.
Sometimes you will need to adjust your rear derailleur, so here are some tips:
On the other hand, the front derailleurs work mainly with the chainrings. The anatomy of a chainring can be seen as below:
There are three chainrings in totals: little, medium, and big rings. The front derailleur will shift the chain onto these chainrings accordingly. Similar to the rear derailleur, the cable, cage, and linkage are involved in shifting the chain.
The derailleurs work only when the pedals are circling. The gears rise and fall in harmony with the pedal movement, shifting the chain from the largest chain to the smallest one, then repeating the reversal process.
Front derailleur can be hard to deal with, so learn more about it right away:
One of the crucial parts of front derailleurs is adjustment screws, often marked as “H” and “L” screws. The H screw adjustment will make a restriction on the right parts and outer cage travel, while the L one limits left and inner cage travel.
If you are not satisfied with the explanation, you can check out this video:
The Guideline Of Putting Bike Chain Back On Derailleur
Now you have understood the bike chain derailleur routing, and it’s much easier to install a chain back on the derailleur. Just follow these simple steps, and they will be all done:
Shifting To Big Ring
Please start with the gear’s condition first by shifting it to the biggest chainring. This will help to release all the tension on the chain at the lowest gear, and it just may help the chain to go back on the gear on its own. A gear lever may be helpful in this step.
However, if the bike chain still refuses to go back to work, shifting to the biggest chainring will also be useful. You can also remove all the jammed objects and check to see if the chains are damaged much better.
Re-Position Your Bike
Since the area that needs fixing is quite close to the ground, if you leave the bike to stand like usual, you have to lower yourself to get access to the bike chain derailleur routing, which may restrict your movement.
As a result, flipping your bike upside down will give you an advantage. Remember to place your bike on the bike saddle and handlebar and remove all the accessories that may get damaged when being flipped.
Fix The Tension
If your chains are still intact or can continue to work, maybe tension release can do the trick to put them back on the derailleur. Pushing the rear derailleur forward will reset the chain’s tension to zero.
Use your left hand, mostly your thumb, to push it as much as you can. Your right hand can lightly lift the chain on the top part and place it onto the chainring. The smallest chainring will be good to go.
Release The Derailleur
Let your hand off the rear derailleur and check if the bike chain is in its proper place. You can circle your bike pedal a bit to see if the chain is working back correctly. Try shifting the gear if possible.
Replace Your Broken Bicycle Chain
In case your chains are broken, you may need to change your chains or fix them. De-tangle your bike chain and remove the broken links.
Then wrap the chain on the smallest gear and the derailleur. Next, run it through the small cog near the front derailleur. Replace the broken link with the master link chain, or simply connect the end together. The length of the replaced parts should be the same as the old chain.
To help with the tension, repeat what you have done before. Pushing the rear derailleur forward with your left thumbs to assure the chain is in the right place.
At this point, check every possible reason for slipping the bike chain. Removed all foreign objects, clogged grease, or dirt, if necessary, clean the whole gears and re-lubricate it. Also, you should see whether the alignment of the chain and derailleur is correct – the wrong alignment will later ruin the shifting gears.
In case the bike chain length is too long or too short, you should delink it and adjust it to the right length. Or if the derailleur is the bad boys causing the problem, it’s high time you purchase the new ones and do some replacement.
Let’s see if there is another way to install your bike chain back on the derailleur:
Tips For Putting Chain Back On Derailleur
All the steps and diagrams will give you an overall view of the bike chain’s function and derailleurs and how to reinstall the slipped chain, but it is always better to know more. Here are some of the tips to lessen the labor when your bicycle chain refuses to work properly:
For old chains, the edges may become sharp when getting chipped off, or rocks or other objects may get stuck in. Therefore, you should wear gloves to minimize the chances of getting cut.
Besides, it’s suggested that you wear protective clothing when fixing your bike chain and derailleur. The lubes and grease can be hard to wash, so you don’t want them to get everywhere near your riding suits.
Let’s keep everything neat when putting the bike chain back on derailleurs. Tie up your hair, sleeve up your shirt, and put away accessories. It will reduce the chances of letting these things mess up in the process.
Cleaning off the gear before fixing it is also a good idea. When the chain and derailleur are cleaned, you can examine the cause of the problem and their states better, so the process will be quick and less tiresome.
You can learn how to wash all the dirt and grease off your gears here:
If you want to make a regular check to avoid slipping bike chain, let’s get chain tensioners. The head screwdriver of the chain tensioner can help you to fix your bike chain at will and fit well with the derailleur.
How many methods can I use to put the bike chain back on the derailleur?
There are at least six methods to put the bike chain back on the derailleur.
Are the steps of putting the bike chain back on the derailleur similar between different bike types?
Depending on the gear types, the steps of putting the bike chain back on the derailleur can be different.
How do you route a chain through a rear derailleur?
You should go from the backside of the gear like you are pulling the chain. Don’t let the chain fall off the front derailleur and place the chain on the rear derailleur’s smallest cog.
How does a chain go on a derailleur?
The chain should be threaded on the front sprockets of the derailleurs.