How To Put A Bike Chain Back On In 4 Easy Steps [With Video]

A chain that keeps falling off is one of the most annoying maintenance issues for beginner cyclists - but luckily, it's also one of the easiest to fix

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reviewed by Robbie Ferri
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Having your bike chain fall off is a nuisance road cyclists and mountain bikes alike will experience at some point.

Besides being irritating, it can also be dangerous – you could slip off the pedals if the chain comes off while you’re standing out of the saddle, or the sudden loss of power could leave you stranded in the middle of a busy junction!

It’s therefore vital to learn how to put a bike chain back on quickly and easily so you can get back in the saddle with minimal fuss.

It’s also important to understand the reasons why your bicycle chain might be falling off, and some quick fixes for a chain that’s falling off every time you hit the road.

Luckily, the BikeTips team has years of professional bike maintenance experience and are here to make the job easy for you.

In this guide, we’ll walk you through:

Read on to get started!

How To Put A Bike Chain Back On In 4 Steps

Step 1. Try To Get The Chain Back On While You’re Still Riding

Photo of a black crankset with the chain hanging off.
© Robbie Ferri/BikeTips

It’s much more common for a bike chain to slip off from the smallest of your chainrings (the front set of gears) than at the back wheel.

If this happens to your bike, there’s a chance you might be able to get the chain back on while you’re still moving.

While pedaling, shift your front derailleur into the position of the biggest chainring (the highest gear). With a bit of luck, the derailleur will drag the chain just enough to catch on the teeth of the chainring, and it should pull itself back into place as you pedal.

This should always be your first response to your bike chain falling off at the front. It could save you from needing to stop at the side of the road at all.

Step 2. Check Whether The Chain Is Trapped Against The Frame

Checking whether the chain is trapped against the frame's chainstays.
© Robbie Ferri/BikeTips

If that hasn’t done the trick, you’ll need to find a safe place to stop and get off the bike for a closer look.

You might find that the chain has trapped itself between the cassette (the rear set of gears) and the bike’s frame. If this is the case, you’ll need to loosen the rear wheel until there’s enough wiggle room to release the chain.

If your bike’s wheels have a quick-release mechanism, simply open the lever and turn it a few times until there’s enough space to pull the wheel out by a couple of centimeters. You should now be able to pull the chain free.

If you’re riding an older bike with hexagonal axle bolts instead of a quick release, the process is the same, but you may find that you need a wrench to loosen the rear wheel.

Whichever type of axle you’re using, always make sure you remember to tighten the wheel again before hitting the road.

Step 3. Push The Rear Derailleur Forward

Pushing the rear derailleur forward to create slack in the chain.
© Robbie Ferri/BikeTips

Change gears to shift your derailleurs into position over the smallest chainring and the smallest sprocket of the cassette.

The rear derailleur on a bike is spring-loaded to keep the chain taught. Using your left hand, push the rear derailleur forward to create some slack in the chain.

This will make it easier to ease the chain back into place and help prevent your fingers from getting pinched in the process.

Step 4. Lift The Chain Back Into Place

Lifting the chain back onto the chainring.
© Robbie Ferri/BikeTips

With the derailleur pushed forward, lift the slackened chain onto the smallest chainring.

Once the front section of the chain is in place, pull the rear end over the smallest sprocket. With both sides of the chain back in position, you can now release the rear derailleur to bring back some tension.

With all these steps followed, you should be ready to get back on the road!

Lifting the chain away from the frame where it was trapped at the cassette.
© Robbie Ferri/BikeTips

Why Does My Bike Chain Keep Falling Off? 5 Possible Causes And How To Fix Them

1. Your Chain Is Worn Or Damaged

A chain wear indicator showing the extent of wear on the chain.
© Rory McAllister/BikeTips

Like all bike components, the chain will eventually wear out with heavy use.

Bike chains become “stretched” over time as the pins holding them together are ground down, meaning they are no longer a perfect fit for the teeth of the chainrings or cassette sprockets.

Not only does this add to the wear on the rest of your drivetrain, it also increases the likelihood of the chain slipping off while you’re riding.

You can check the condition of your bike chain with a simple tool called a chain wear indicator. If the tool is able to slot into the gaps in the chain (as in the photo above), it’s time to replace it with a new chain, using a chain tool.

Similarly, your chain can be damaged by an impact, debris caught in the drivetrain, or a dodgy repair job. If you have any bent or broken chain links, the chain needs to be replaced, as it will keep slipping off the teeth and can also cause further damage to your drivetrain.

Your chain could also be the wrong length for your bike, meaning it won’t have the right amount of tension and is more likely to fall off.

If you suspect that a fault with the chain itself could be the reason it keeps falling off your bike, check out our guide on how and when to replace your bike chain here!

It’s a fairly easy job, particularly if your chain uses a quick link (also known as a “master link”). You can also use the old chain to copy the chain length, using the ends of the chain as a guide.

2. Your Rear Derailleur Hanger Is Bent

Checking whether the derailleur hanger is bent.
© Robbie Ferri/BikeTips

Also known as “frame-savers”, the rear derailleur hanger is a piece of metal that connects the rear derailleur to the frame.

Derailleur hangers are intentionally designed to break. While this may sound odd, it allows them to act as a failsafe to prevent more serious (and costly) damage to your bike’s frame or derailleur.

However, once the derailleur hanger is bent, the derailleur itself gets pushed out of place. This creates all kinds of headaches shifting gears and makes your bike chain more likely to fall off.

3. Your Derailleur Limit Screws Are Wrongly Adjusted

Pointing out the limit screws on the front derailleur.
© Robbie Ferri/BikeTips

The derailleur limit screws restrict the movement of the derailleur cage. It’s their job to keep the derailleurs in the right position over the chainring or cassette.

However, if the derailleur limit screws haven’t been set correctly, they won’t leave the right amount of space for the derailleur to move which increases the likelihood of your bike chain slipping off.

If your chain is falling off at the front, look for the derailleur limit screws on your front derailleur. The inner screw (often marked ‘L’ for low) restricts movement inwards, while the outer screw (often marked ‘H’ for high) restricts the derailleur’s movement outwards.

If the chain keeps slipping off at the inside of your smallest chainring, you might need to tweak the low screw. Shift the chain to the smallest chainring and take a close look at the position of the derailleur cage.

There should be a very small gap of about a millimeter between the chain and the derailleur cage. If it touches the chain, the limit screw is too tight. If the gap is too wide, finely adjust the screw until it’s in just the right place.

If your chain is falling off the outside of the largest chainring, the process is the same – but you’ll need to adjust the ‘high’ screw instead.

Pointing out the limit screws on the rear derailleur.
© Robbie Ferri/BikeTips

If your chain keeps slipping off at the back, the rear derailleur limit screws might need tweaking.

A word of caution, however – there is more potential to damage other components of your bike by incorrectly adjusting the derailleur limit screws at the rear than there is at the front.

If in doubt, it’s best to go to a bike mechanic to be on the safe side!

4. You’re “Cross-Chaining”

The bike's drivetrain in a "cross-chaining" position, with the chain on the largest chainring and the largest cassette sprocket.
© Robbie Ferri/BikeTips

Cross-chaining” is the cyclists’ term for riding with the chain either on the biggest chainring and the cassette’s biggest cog or on the smallest chainring and the cassette’s smallest cog.

In either of these gear combinations, the chain is running at a diagonal angle between the chainrings and the cassette. Not only is this inefficient due to the increase in friction, it can also make your chain more likely to slip off.

5. Use A Chain Catcher

A black chain catcher on a city bike.
© Rory McAllister/BikeTips

Chain catchers are small plastic or metal barriers that attach to your bike’s frame to physically block the chain from falling off the inside of your smallest chainring.

Some bikes have them installed as standard, but you can also buy them separately. They’re usually fairly cheap and easy to fit.

However, a chain catcher won’t help if your chain is slipping off anywhere other than the smallest chainring.

It’s worth exhausting all the other possibilities before relying on a chain catcher, as you could be masking a problem somewhere else on the drivetrain which is causing the chain to fall off.

Robbie’s Full Video Maintenance Guide: How To Put A Bike Chain Back On

Check out the BikeTips YouTube Channel here for walk-through bike maintenance guides and more!

Time To Get Riding!

Now you know how to put a bike chain back on, you’re ready to get back in the bike seat and hit the road!

If you’re still finding that your bike chain is coming off regularly, it’s worth taking your bike to a your local bike shop – they might still be able to find a solution that saves you replacing your entire drivetrain!

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As a UESCA-certified cycling coach, Rory loves cycling in all its forms, but is a road cyclist at heart. He clocked early on that he had much more of a talent for coaching and writing about bikes than he ever did racing them. In recent years, the focus of Rory's love affair with cycling has shifted to bikepacking - a discipline he found well-suited to his "enthusiasm-over-talent" approach.

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