Why Mountain Bike Chains Break: (6 Reasons & Easy Fixes)

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Why do mountain bike chains break even though they are made to last longer?

Like any moving object, mountain bike chains also have an expiry, but sometimes it comes too soon.

This could be due to multiple reasons, such as the following:

  1. Wearing of the chain
  2. Impact 
  3. Poor maintenance 
  4. Shifting gears under heavy load
  5. Worn cog 
  6. Bent chainring

In this post we shall do a deep-dive on all the common reasons of why mountain bike chains break.

Let’s dive in!

Why Mountain Bike Chains Break Due To Wearing?

Worn Mountain Bike Chains
Worn MTB Chain

Chain stretch caused due to chain wear is the reason for most mountain bike chains to break.

Chain wear could happen due to multiple reasons.

Typically, a mountain bike chain that has traveled for over 2500 miles is more prone to chain wear and stretch.

Bike chains that are not taken good care of are more susceptible to wear at a faster rate.

A worn chain that is not replaced will likely snap in the middle of a ride.

Does Impact Lead To MTB Chain Break?

Mountain Bike Impacts
Riding Tough Trails

If you are an advanced MTB rider and ride through tough bike trails very often, sometimes you can encounter bike impacts or falls.

These impacts can lead to several damages to a bike, including chain break.

A rock strike more often leaves you with a broken chain.

While a bike chain breaks one link at a time due to wear, an impact can lead to the snapping of multiple links at a time.

Why Mountain Bike Chains Break Due To Poor Maintenance

Why Mountain Bike Chains Break Due To Poor Maintenance
Maintaining MTB Chains

Timely and consistent maintenance is essential to maintain your MTB chain in good shape and avoid premature breakage.

The dirt that is built up in the form of mud, dirt, gravel, and gunk, could lead to wear if not cleaned up time-to-time.

When dirt is built up after every day and is left without cleaning, the chain weakens quickly.

So now you know why mountain bike chains break due to poor maintenance of your bike chain.

Shifting Bike Gears Under Heavy Load

Shifting MTB Gears Under Heavy Load
Shifting MTB Gears Under Heavy Load

Climbing or biking uphill is part and parcel of mountain biking.

However, when you are pumping your pedals hard and shifting gears while you move up, it is very likely that your mountain bike chain breaks.

Worn-Out Bike Cogs And Bent Chainring

Worn Out MTB cogs and bent chainring
MTB Cogs And Chainring

If your MTB bike cogs are worn out, it could lead to chain skipping and getting caught between the gears.

Also, the chainring cogs can get bent as a result of wear in your MTB’s chainring.

This could eventually lead to the chain getting stuck and broken.

Quick And Easy Ways To Fix A Broken MTB Chain

Easy Ways To Fix A Broken MTB Chain
Mountain Bike Chains

In order to fix a broken mountain bike chain, you must first identify and eliminate the broken link.

Typically one set of links, which includes the outer plate, inner plates, rivets, and rollers, must be removed to fix the chain.

A chain tool will come in handy in making the job easier.

A bike chain tool will aid in pushing and removing a rivet out of the link.

If your bike needs a chain tool in the multi-tools, you can always get one at a bike store.

Here’s how to use the chain tool to fix MTB chain:

First, position the chain in such a way that the link that needs to be removed hangs lower.

Once it is placed, thread in the chain tool until the rivet is pushed out altogether.

This will lead to the rivet coming off fully. The exact process could be carried out for all the broken links that need to be removed and replaced.

Follow the steps below to know how to use the chain tool:

  • Position the chain into the lower end.
  • Once the chain is positioned, begin threading in the rivet tool until it forces the chain rivet almost all the way out. This will lead the chain to quickly come apart.
  • Repeat this process until all portions of the broken chain are removed.

Tip: Before you set out for a mountain bike ride, check if your tool box has a chain tool. If you don’t have one, purchase one and keep in your toolbox to avoid messing up chain removal while you are on the trail. You can also keep extra links in your toolbox to replace a broken link whenever necessary.

9 Common FAQs on Why MTB Chains Break

1. Which mountain bike chains last the longest?

Earlier, Shimano and SRAM chains were considered to be the most durable Mountain bike chains.

However, today there are multiple other brands too that offer long-lasting chains.

This list of brands includes Wippermann Connex, KMC, Muc-off, etc.

In addition, Shimano and SRAM themselves have multiple options in durable chains.

2. Why does a new bike chain snap?

If the cheap mountain bike chain that you recently bought from the store snapped during the first or second ride, look for no other reason.

It is very likely that the bike chain is made of low-quality material and can only get you up a few miles.

The other reasons are heavy load shifting gears while climbing up or a new chain that is threaded on a worn-out chainring or cog.

3. Why does the MTB chain pop when pedaled hard?

There are multiple reasons why the MTB chain pop when pedaled hard.

This includes having a worn chain, stiff or bent link, or dirt or gunk that clogs up the chain.

Turn the cranks and inspect with your eyes to see if any of these problems are causing the chain to pop.

A misaligned derailleur can also lead to the chain popping when pedaled hard.

4. How much does it cost to fix a popped chain of your mountain bike?

Here you go, if you are wondering how much it would cost to fix a broken chain. Essential MTB chains typically cost you around $15 for repair, whereas high-end MTB chains could cost you from $25 to $60.

More expensive chains generally are more durable and offer better shift quality. They are typically much lighter compared to the basic MTB ones.

If you are getting the service from a shop, it costs you $ 20 to $30 on average.

To do it yourself, you can buy a chain tool, which would cost between $10 to $50.

5. How do you align your mountain bike chain?

Chain alignment refers to how the sprockets and chain are related to the bike’s centerline.

The center line is an imaginary line that passes straight through the middle portion of your bike.

The chain should stay parallel to this imaginary line.

If your mountain bike chain needs to be aligned, you must first adjust the wheel so that it falls right in the center.

Next, you need to check if the sprockets are correctly aligned.

Then you have to make sure that the drivetrain parts are well-aligned and threaded in the chain.

6. Should the MTB chain be touching the derailleur?

Ideally, the mountain bike chain should stay near the inner plate of the front derailleur cage but not touch it.

A 1 mm to 2 mm gap should be maintained between the two.

If the gap is larger than those above, you can use the L screw to turn it clockwise and move the derailleur and the chain closer to each other.

7. How do I know if my bike chain is aligned?

Checking your bike chain alignment does not require any fancy tool.

A ruler or a yardstick would be handy in assessing the same.

First, you have to stand behind the rear end of the bicycle. Now keep the ruler at the top of the rear cog.

If you find the chain achieves a straight line with the ruler, you can conclude that the MTB chain is aligned.

Another method is slowly turning the cranks and checking if the chain rotates from the rear cog to the chainring.

Make sure that the path of the chain is straight as the chain turns across the drivetrain.

A case of a misaligned chain would have the chain approaching the chainring from the side. In this case, the chain would gradually grind down the teeth of the chainring.

Ideally, the chain should be perfectly aligned with the chainring, hitting it head-on.

8. How do you repair a broken mountain bike chain?

Getting stuck on the trails with a broken bike chain is not at all a pleasant situation. Hence, you must know how to repair your chain in case of such an unprecedented situation.

Therefore, you must always carry a multi purpose bike repair tool box on your mountain bike for every ride.

You must first remove the broken link using a chain breaker tool to repair a broken chain.

When you break a link, make sure that the pin is partially removed while pushing it out.

It is recommended to take help from someone while you reinstall the link. However, if you are on your own, don’t worry; you can manage it yourself.

Pushing the pin back in its place using a chain tool would be best.

Lining up the tool and the pin will take a lot of work, so be prepared for it.

However, if you are using a new chain with a special link, you can do this effortlessly without using a chain tool.

Once you attach the link, it is going to stay stiff. You can work around back and forth using your hands to loosen it and bend around the gears.

9. Does WD-40 ruin a bike chain?

WD-40 is clean with mild lubricating properties. It will help in keeping the bike chain rust and corrosion-free, preventing premature breakage to a great extent.

It is not known to create any harm to the mountain bike chain.

However, it is not a good idea to go into wet trails with just WD-40 applied because it gets quickly washed away in wet or slick conditions.

It is always better to o resort to lubes for lubrication of the bike chain and WD-40 to clean and push away water from the chain.

WD-40 will also help in removing rust from the bike chain.

First, you have to spray the WD-40 on the rusted area and leave it for 3 to 5 minutes. After which, you can scrape the rust off using steel wool.


I hope through this article I was able to help you understand why mountain bike chains break and how its is easy for us to repair them quickly.

P.S. If this article was helpful to you, you should also consider checking out similar deep dives I did on worn MTB chains and chainrings.

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Team Biking KnowHow

Rohan runs Biking KnowHow along with his team. Rohan has been a mountain biker since 2005. His mission is to simplify mountain biking for everyone. All Biking KnowHow content piece is thoroughly fact-checked. Our content is backed up with leading research and inputs from expert cyclists.