Bike Chain Keeps Falling Off Single Speed Bike? 10 Reasons + Fixes


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It’s a pleasant summer evening. The sunset looks phenomenal, the weather is delightful, and you’re cruising on your single-speed bike. A sudden jerk nearly pulls you off your bike as you find yourself annoyed to the core, seeing that your bike chain has fallen off. Again! This bike malfunction happens very commonly and can be a quick mood killer and (without wanting to be too much of a drama queen) quite simply ruin your day! But why does this happen?

If your bike chain keeps falling off your bike, it is usually due to changes in your bike’s system over prolonged use. Identify the issue, and take corrective action like tightening screws or having replacements.

There are lots of possible factors at play here!

The following article is an in-depth description of why your single-speed bike chain keeps falling off, the various factors that contribute to it, and how the situation may aggravate if you ignore it.

The article also discusses the tips and methods you can use to prevent further accidents and ensure your bike is functioning at its best (source).

Bike chain keeps falling off single speed bike

10 Reasons Why Your Bike Chain Keeps Falling Off

Although a more common phenomenon in older bikes, chains can also slip off in new bikes, irritating their owners. There can be multiple reasons behind this mishap.

1. Loose Screws on The Drivetrain

The drivetrain on your bike is held in place by multiple screws and nuts. This leads to a smooth chain motion while your bike moves.

However, if the drive train is loose, it can move around due to the force you generate while pedaling.

This shifting causes your bike chain to come off, leading to a hassle while trying to put it back in place. This problem may also be dangerous, especially if it happens while you’re in traffic.

2. Having a Stretched Chain

Due to prolonged use, your bike chain links may open up a bit and cause your chain to have a stretched look.

This may also happen due to hard pedaling by heavier riders over long distances. The stretched chain tends to slip off the front cogs when you try to pedal vigorously. 

The ideal bike chain should be taut and firmly placed over the chain cogs’ teeth. If you notice your bike chain is hanging and looking limp, it’s a sign that you should buy a new chain.

Stretched chains have links that have become larger throughout use and are now way too big to be effectively held by the teeth for driving the bike. 

Stretched chains often get confused with chains that are too long. Chains that are in good condition but simply too long for your bike can lead to trip-ups in your bike system and frequently fall off.

Stretched chains start perfect but become faulty over time. 

3. Worn Out Teeth on Bike Cogs  

The chain works in tandem with the cogs on which it sits. The cogs have teeth to hold the chain in place and allow you to drive the bike with your pedaling.

However, the teeth can get worn out as your bike gets older and cause the chain to slip off.

This way you will not be able to pedal fast as the teeth will not hold the chain properly due to their reduced size and altered shape.

Stretched bicycle chain
A stretched chain is a common reason why a chain will fall off. The links become too large to effectively hold the teeth

4. Bumps and Potholes

If you ever ride your bike in a pothole or over a deep puddle at high speed, the chain will almost certainly slip off.

The sudden jerk can knock the chain off the cogs or even lead to the chain getting tangled up with one of the cogs.

This can even damage other parts of the bike after which you will have to replace multiple parts over a single act of carelessness. The bumps may also lead to the lower part of your chain colliding with the ground (if the pothole is deep enough), risking permanent damage to the chain and front cog. 

5. Incompatible Parts and Components

If your bike is using components and parts from various brands or different sizes, it could lead to a troublesome drive train and dissatisfactory chain performance.

This usually happens when owners are unaware of what their bike needs and accidentally get incompatible parts installed in their ride.

The chain incompatibility could happen due to multiple reasons:

  • The cogs teeth are too small for the chain
  • The chain is too long for the bike’s drivetrain components
  • The front and rear cogs are not compatible with each other’s motion

6. Bent Teeth on Cogs

Once again, this a problem caused by prolonged use of the bike. Bent teeth result in the high unpredictability of your bike chain.

The teeth may lose grip on the chain, especially at high speeds, and cause it to slip off.

Unfortunately, bent teeth usually mean that it is high time to replace the bike cogs, although, in some cases straightening the teeth may fix the problem.

7. Denting on the Chain and Cog Cover

New generation bikes have an aluminum cover protecting the cogs and chain. The aluminum cover protects the chain and prevents damage in the case of collisions or pavement contact.

However, over time, denting on the cover may lead it to cave in and make contact with the bike chain and cogs (source).

This can cause your chain to get stuck or fall off if the cover gets in the way. Your ride becomes stiff and if this problem is not fixed, it can damage your chain, wear out cog teeth, and even lead to accidents.

8. Rusty Chains

If your bike is older and unloved, the chain will certainly develop rust.

Rusty chains are stiff, do not move well, and cause excessive friction between the individual chain links.

This will give you a choppy ride while also causing your chain to fall off repeatedly since it will not move over the cogs smoothly.

9. Misalignment of Chainrings (sprockets)

A chain is composed of many small rings that link to each other, giving the chain its flexibility.

The rings are attached in perfect alignment and if one of them is off course, the chain can slip off the teeth and then come clean off the cog in a literal ‘chain reaction.’

10. Damage to the Bike’s Frame

If you have ever had an accident or run through a deep pothole, you may have noticed your bike functioning strangely after.

The chain probably keeps falling off. This is probably due to the deformed bike frame that has lost its shape due to the trauma.

Since all the other components are attached to the bike’s frame, it needs to be in pristine condition.

Replacing a slipped bicycle chain
Repeatedly replacing a slipping chain can be a soul-destroying experience!

9 Fixes To Stop Your Bike Chain from Coming Off (Fixes!)

I’m sure many of you are wondering exactly how you should deal with this annoying problem. The following tips will not only prevent your bike chain from falling off but are also good tactics for maintaining overall bike health.

1. Ensure the Drive Train Components Are Firmly In Place 

The drive train is your bike’s engine. The chain tends to slip off if the components are not held firmly in place.

Therefore, you should always check the screws and nuts holding the derailer, cogs, pedals, and wheels in their place, ensuring they are tight.

This smart move will make your bike chain move effortlessly while preventing all potential issues. Better safe than sorry!

2. Replace your Bike’s Cogs

Prolonged use of your bike can lead to excessive wear on the cogs.

Therefore, you should replace your bike’s cogs if you notice that the teeth are worn out or the cog itself is cracked or bent out of shape.

This tip will ensure a smooth function of the drivetrain and prevent the chain from falling off. The fresh teeth on the new cogs will hold the chain well, allowing you to pedal fast.

3. Pulling Back the Rear Wheel

If you have a longer chain on your bike that refuses to let you pedal fast and keeps falling off, you can try another tip to ensure tautness and great functionality.

Loosening the bolts on either side of the rear wheel will allow you to pull back the wheel and create tautness in the bike chain.

This way, you can easily bring your bike back to its glory without having to replace any parts. The limit to how far back your rear wheel goes depends on your bike (source).

4. Lubrication and Care

If your bike’s chain or cogs are getting rusted, lubrication is in order.

Having a well-oiled system will allow your chain to be smooth and flexible.

This way, it will be able to go over the round surface of the cogs without any friction and will not bunch up at any end. The lubrication will also allow you to turn the pedals in the opposite direction without the chain falling off! 

5. Realigning the Chain

The chain links can lose their alignment through prolonged use, thus it is better to check the chain if it keeps falling off.

The alignment can be checked using a ruler and the chain may be hammered out to bring the rings back in alignment. However, in extreme cases, buying a new chain may be necessary. Hammering old and rusted chains is a bad idea.

6. Checking the Bike’s Frame

Keeping your bike’s frame under careful watch is a lesser-known, albeit effective, method of ensuring that your bike’s chain stays in place.

If you notice that the frame is out of shape or misaligned with the wheels, you should immediately get it checked. The frame holds all the components together and damage to it will lead to collateral damage all over your bike.

7. Being Careful about Avoiding Potholes

The same applies to cars and all other modes of transport.

Your bike uses a more delicate chain and frame in comparison to other vehicles thus, you should avoid potholes and ditches while moving at high speeds.

You can increase your bike’s life if you look after it and prevent the chain from slipping off your single-speed bike. You can also prevent potential damage to your bike’s frame by exercising precautions.

8. Getting Bike Parts Replaced After Doing Your Homework

Often we get tempted by cheaper means of getting something done. However, if you want your bike to perform at its peak, trying to save money on a vehicle that could save or take your life is a bad idea!

You should always purchase the best parts that come with warranties and contact your bike dealer before making any purchases. Incompatible bike parts can entail more damage to your bike and cause poor performance. 

Also, mixing components from different brands on a single bike should only be done with the guidance of a professional, as this can also lead to faulty performance.  

9. Love your Bike

This goes without saying. If you want your bike chain to stop falling off, perhaps you should start looking after your bike. This means:

ActionReason
Wash your bike at least once per weekEnsures no debris is stuck in chainrings
Lubricate after every washMaintains chain flexibility and health
Keep aluminum cover in good conditionHelps protect the chain and front cog from damage
Keep tires at optimum air pressureTakes the excessive load off the chain to prevent stretch

Final Thoughts

Your bike will always be there for you and be a ready companion for all sorts of trips.

When your car may refuse to start and subway stations close down, your bike will be ready to take you from A to B.

However, to prevent the common issue of single-speed bike chains falling off, you must know the causes of the mishap. If you know the causes, you can certainly take steps to ensure that the problem goes away.

Using the tips we have mentioned, your bike chain will stay in pristine condition, and more importantly, stay in place!

Martin Williams

Martin has been tearing up all sorts of trails on a range of bikes ever since he was young. He once cycled across France, and once fell into a canal on a hybrid. He writes about everything to do with cycling on our site. You can find out more about him at bicycle2work.com/about-martin-williams/

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