Reasons Why Bike Chain Keeps Falling Off and How To Fix

Aug 29, 2022


It is not uncommon for a bicycle chain to get dislodged every once in a while. However, if it continually comes off, there is obviously a problem that needs to be fixed. Chain is part of the drivetrain system, and it can be difficult to determine the cause of a problem because multiple factors can be responsible for it.

Since there are many possible reasons for the chain falling off, we decided to conduct a comprehensive investigation into these reasons, as well as possible remedies to the issue and strategies for avoiding it in the future.

Therefore, in this article, you will learn all about the mechanical malfunctioning that can contribute to chain drop, as well as the solutions to these problems.

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Top Possible Reasons of Bike Chain Falling Off

Unsuitable Chain Length

The length of chains that are relatively new or have just been lightly utilized is often shorter than the length of chains that have been used for longer. It's not because your bike is fresh new that the chain keeps falling off of it as you ride it. If the chain does not fit, it most likely has become slack, which causes it to be excessively loose.

It may make the chain shorter, or it could make it longer. The link that connects the chainring to the cassette will curve when the chain is extended. It is expected that this will arrive in the form of a curve when it does arrive. The chain travels in a U-shaped pattern from the bottom chainring to the top cassette, which is a dead giveaway that there is an issue.

Most of the time, it's because you bought the wrong size chain for your bike. When the chain is excessively long, the derailleur won't be able to grasp the additional chain length. As a result, it will continually slip off.

Wrong Size of Chain

It is not always easy to tell if the chain on your bicycle is the incorrect size. When purchasing a bike chain, the length of the chain is not the only factor you should consider. You must choose the appropriate width as well. If you use a chain of the wrong size, it will come off frequently.

It's likely that you won't notice anything wrong with a brand-new chain at first because it will work perfectly with the chainring and the cassette.

The most common reason for a chain drop is that the chain is overly long; when this happens, the chain will drag the chain keeper off of itself. It is important that the chain is of the appropriate size for the various components of the system, particularly the rear derailleur, and that it is not overly tight or loose.

As the chain gets older, the problem of links coming loose and falling off becomes more severe. If you ever need to know the precise measurement of the chain on your bicycle, you can look it up online. Or, if you want to know the appropriate chain size, it is preferable to seek a specialist’s help.

Worn Out Chain

When a chain has been used for several years, the holes in the chain may appear uneven. If you take a closer look at the chain, you can see the various signs of wear and tear that have taken place over time.

You should examine the chain for any scuffs or scratches not only on the exterior of the holes but also on the interior of the openings.

If you look closely enough, you can see the wear and tear on the bike chain. You can identify the link in the chain with the scratches and put a mark on it. If the chain keeps breaking in the same spot, you know what to do; go for a new chain.

Dirty Chains With Clogged Holes

Grime is one of the potential causes of the chain getting dislodged. While you ride, some of the dust and debris from the road gets stuck to the chain and leads the chainrings to get jammed up.

A relatively small number of blocked links in the chain is all that is required to initiate chain falling-off issues. When the clogged hole gets to the chainring, it prevents teeth from fitting in. 

Because of these minor alignment issues, the chain will need to be removed from either the chainring or the cassette to continue.

Cassette Damage

When it comes to determining where the issue lies, the cassette presents a greater challenge than the chainring. You will need to examine each cassette ring to identify the one that is broken on the cassette. You can do this by simply changing the gears. If the chain keeps coming off, count how many gears are causing the problem. And, when a bike falls, all the rings may not line up properly. Based on this analysis, you can decide whether you need cassette repair or replacement.

Moreover, the teeth on the cassette serve as the point of attachment for the chain to the drivetrain of your bicycle (cogs). Excessive use, a lack of maintenance, or exposure to grime, salt, and weather can cause the chain's teeth to wear out, leading to the chain slipping.

Derailleurs Misalignment

When the derailleurs at the back are not in their proper positions, the gears will shift audibly. If the alignment is substantially incorrect, the chains have a chance of coming off. Before you head out for a bike ride, check to see that the rear derailleurs are correctly adjusted.

Derailleur-related issues are typical for older bikes. Bicycles with multiple gears and shifters are particularly susceptible to this issue. The bike handle's shifter allows you to change gears, and if the chain comes off while changing gears, the issue could be with this part. You can use this technique to identify faults with the derailleurs and cassettes.

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How to Fix a Bike Chain That Keeps Falling?

After becoming familiar with the potential reasons for the chain coming off, you should also know how to fix it. If the problem is correctly identified, it can be easily solved. One or more of these solutions may help you resolve the problem. The fix may be as easy as cleaning the link or as complex as replacing multiple drivetrain components. We're going to zero in on these DIY tasks that you can easily complete. If you still experience any difficulty, you can talk to a professional technician for assistance.

Chain Cleaning

The chain on your bike acts as a kind of mechanical log of your cycling journeys, collecting debris like sand from arid rides, clumps of pollen from spring rides, and rusty bits of road grit from wetter rides. If you don't clean your chain, the dirt will turn into a grinding paste that will wear out your chain, make shifting difficult, make cycling uncomfortable, and lead to a waste of energy.

Maintaining a clean drivetrain is essential if you want to get the most speed out of your bike without breaking the bank. A clean bike, as the adage goes, is a fast bike.

Your lube, riding conditions, and mileage will all play a role in how often and thoroughly you need to clean your drivetrain. The frequency with which you must perform a thorough cleaning is also inversely proportional to your skill with preventative maintenance. But if your drivetrain sounds gritty, and every ride leaves you with a calf tattoo, or you have an approaching race, it's probably due.

Here is the quickest and easiest way to clean your bike’s chain:

This simplest of methods involves wrapping the chain in a clean, lint-free cloth and then pedaling backward through it to remove surface grime. You'll need to rinse and repeat until the rag stays substantially clean. The chainrings and the dirty derailleur pulley wheels can be cleaned with the rag. Baby wipes are another option that does the job well enough.

After the chain has been cleaned reasonably, you can re-lube it as necessary. Since oil-based lubricants can aid in floating impurities to the surface, you can wipe the chain several times until it appears clean.

In some cases, such as when using a dry lube, it's recommended to clean the chain after each ride. Light cleanings like these should be performed regularly, as described above, to reduce the frequency with which deeper cleanings must be performed. However, one of the more comprehensive procedures should be used if your drivetrain is already highly dirty.

Please note that while using a rag dipped in a degreaser may produce better visual effects, it combines the degreaser with your dirty lube rather than cleaning it. In the end, you'll only have chain lube that isn't as effective as intended.

Correct Cassette Alignment

You can use the wrench to realign the cassette if it's not in the right place or if it's not working properly. As with smaller gears, you can use pliers to adjust them. The process of figuring out the issue and coming up with a solution can take a lot of time. It is strongly suggested that you seek the advice of a certified specialist if you are having problems with the cassette. They use specialized tools to measure the cassette and ensure that everything is in the correct position.

Rear Wheel Adjustment

If the chain on your bicycle is stretched, you can change the length of the chain by adjusting the rear wheel. If you remove the bolts, the wheel that is in the back can be pulled backward. When you are finished correctly adjusting the chain, you can then secure the back wheel by turning the bolt clockwise.

Doing this will help you solve the issue without the expense of purchasing a new chain.

Correct the Chainring Wheel Uneven Surface

A wrench is an ideal tool to adjust the chainring so that it no longer has an uneven surface. Taking care of any teeth that are crooked or misaligned should be one of your top priorities. Using the wrench, you can easily realign chainrings. You can also use a bigger wrench to straighten up the chainring if it is bent slightly in any direction.

It is recommended that you take off the chainring before making any adjustments. This is because if you do this, other components will be protected from any potential damage.

Derailleurs Adjustment Correction

There are two distinct ways in which the derailleurs can be readjusted. It is necessary to use the limit screw-in to keep the chain from coming off. To correctly attach the chain to the cassette and the chainring, you will need to make a few changes to this screw.

It is also important to ensure that the metal bracket that secures the derailleurs to the frame of the bicycle has the appropriate amount of adjustment. It is a setting that needs to be adjusted, even on the most innovative bicycles.

Bike Chain Replacement

You will need to replace the chain if you have exhausted all other possible solutions to the problem of it falling off and the chain being worn out. Finding a certified specialist who is also well informed about bicycles is something you absolutely must do. He will be able to help you find a chain that satisfies all of your requirements in terms of width and length.

To ensure that there are no more problems in the future, he will adjust the chain so that it is in perfect working condition. Generally speaking, it's a simple problem to fix; even if you are a seasoned rider, you should be able to finish the repair without assistance from anybody else. It's possible that the internet may provide you with several useful guides that will walk you through the process of replacing the chain.


The chain plays a crucial role in transmitting rotational motion on bicycles. Remove the chain, and the bike will not move. The chain usually comes off if there's a problem with the bike's gears or derailleurs. We have detailed different steps to narrow down the cause of the problem and how to fix it.