Motorbike Chain Cracking Issues

A broken chain is less common than it used to be but that doesn’t mean you should neglect the regular maintenance that ensures your chain is kept in good working order. After all, neglecting your motorbike chain can result in a host of issues with a break being arguably the most sever, hazardous, and costly.

As with most common failure modes, many significant factors cause a motorcycle's chain to crack and, in turn, weaken before completely snapping. Leading reasons include 

  • Lack of chain maintenance
  • Worn out or rusted chain
  • The wrong chain tension/alignment

The primary focus of this article is on cracking as a failure mode and the implications this would potentially have on your motorcycle's overall performance. 

Understanding The Term 'Cracking':

A cracked chain is one of the rarer and most extreme causes of chain failure. As such, you might not have come across it before so it’s important we take sometime to fully understand what we mean by it.

By its very definition, cracking is damage caused by stress in a material that can be exaggerated by other factors, such as corrosion, fatigue, high pressure, or construction material. 

The primary cause of a crack in any metal is the sudden application of an external force. When this happens, the metal is subjected to stress, which can cause it to break. The pressure a metal can withstand before breaking is known as its yield strength.

Several factors can contribute to the sudden application of an external force, such as an impact or a blow. In some cases, the metal may be weakened by corrosion, reducing its yield strength and making it more susceptible to cracking.

It is important to note that not all cracks are bad. Many metal structures are designed to fail in a controlled manner to protect the rest of the structure from damage.

Motorcycle Chain Cracking Causes:

As your motorbike is such a complex piece of technology, simple, everyday issues can arise. However, the best cure is prevention, so it's essential to know which warning signs to look out for. The following are the most typical examples of what causes the eventual cracking of your bike chain. 

Issues That Lead to Cracking Are:

  • Fatigue of The Chain Itself – Which gradually worsens
  • Overloading of too much weight, especially when the bike is changing gear and under the most stress
  • Wear over some time
  • Sudden impacts, such as rock damage
  • Lack of lubrication
  • Lack of regular, thorough maintenance 
  • Incorrect tension over a prolonged period 
  • Narrow chains are becoming too thin, so higher quality control standards should be used. 

The Significance of Chain Wear: 

Despite all these reasons, wear is the most common culprit. For example, if a chain has been ridden for thousands of miles, it will eventually stretch out. Likewise, a ridden chain will be longer from link to link than a newer chain because the chain is stretched and worn; the metal fatigues, hence becoming more susceptible to failure, as it has to work harder than intended.

In addition, as the chain wears, the chainrings and cassette (gears in the rear) will also fatigue. Combine those factors; it just takes one lousy gear shift to finally crack your chain. 

To combat this, we recommend having your chain checked at least once a year, which will prevent any cracking issues. In addition, we can't stress enough the importance of regular chain maintenance and lubrication. 

Similar to our articles based on the failure modes of alignment and abrasion issues, maintenance needs to be planned and conducted regularly to obtain maximum performance from a set of chains and sprockets. This will ensure optimum chain life and reduce downtime and minimise inconvenience when chain replacement is necessary. The cases we highlight throughout this article are typical examples of failure modes.

However, we confirm that each can be avoided with a bit of forethought.


Maintaining Your Chain (Preventing Cracking from Occurring)

Understanding The Parts of Your Bike Chain

Your chain is made of five pieces.

  • The outer plate
  • The inner plate
  • Pin
  • Bush
  • Roller

Without proper maintenance, your chain will start to rust, another factor involved in the eventual cracking. When a link is rusted enough, it becomes fragile and can crack. As mentioned above, the other significant reason a motorcycle chain cracks is the wrong applied tension. 

If the chain is too loose, it can come out of alignment with the sprockets, which will likely cause a jam.

There are simple actions you can take to ensure the life of your chain, minimising the chances of it cracking:

  1. Get A Chain Wear Indicator: This will help monitor the wear of your chain regularly.
  2. Don't Reuse Master Links: There are a few reasons why you might not want to reuse master links in your motorcycle chains. First, they can add weight to your chain and make it less efficient. Second, they can wear out quickly and must be replaced more often. Finally, if you're unlucky enough to get a defective master link, it could cause your chain to break and leave you stranded.
  3. Use A Proper Chain Lubricant: Renold Lubricant Advice will assist with this.

What To Do With a Newer Chain

Chains can crack at any stage of life, although it becomes more common the older they get. If your chain is still relatively new and there are no other suspect plates, you can just replace the one link within which is visible. 

Install A Quick Link – As A Quick Fix

Quick links come in many different sizes depending on the number of speeds your bike has. 

From 8-12 speed, chains will all use different quick links that are not cross-compatible. So if only the outer plates are broken, you can cut them out, install the quick link, and ride off as if nothing happened. 

If an inner plate breaks, you must cut 1-1/2 links out of the chain before installing the quick link.

Ongoing Thorough Chain Maintenance

A chain crack and break are rarely isolated incidents but more commonly the sign of a more significant issue. 

As echoed at the start of the article, a chain breaking during a ride is usually preventable with a little extra effort in maintaining your chain. 

After any long ride or during every oil change, you should clean off any dirt or road grime built up on the chain. You can do this by wiping it down with a  chain cleaner or parafin.

Every time you clean the chain, make sure to re-lubricate it. Then, spin the back tire and lube the entire chain.

At the same time, inspect the chain for rust and cracks. If you see a large amount of either, it might be best to replace the chain and not take any chances.

Every chain has one link that comes apart; this is needed to put the chain on in the first place. Look at and examine that link and ensure it's still intact.