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Why Do Road Bike Chains Break? Causes and Fixes

Many components, including the chain, ensure that your road bike works correctly. Each link of a chain is held together by pins. It transfers power from the pedals of your road bike to its driving wheel, making it move forward. As the chains are being used consistently, they often end up breaking. Why is this so?

A road bike chain will gradually wear and tear with use. An overused chain transfers power poorly and can break. It can get damaged when it is under too much tension, gets bent or twisted, is worn and stretched out, or has suffered an impact.

There are numerous reasons why these problems may arise. Let’s look deeper into how a road bike chain can malfunction and break.

bike cassette and chain up close

Four Ways a Road Bike Chain Can Break

Several reasons come into play when a road bike chain breaks. Some of these will be discussed in detail below. 

The Chain is Under Too Much Tension

This is the most common way your road bike’s chain can get damaged. Although tension in the chain is vital for its functioning, it must not exceed the optimal limits. This is because if there is too little tension on the chain, it will fall off the cassette. However, the chain may snap and break if the tension is too high.

A chain will break when too much tension is applied to it due to hard pedaling while shifting. Thus, as per a general rule of thumb, try your best to ease up on the pedals while making a shift.

Doing so enables the chain to jump smoothly to the next gear. If too much pressure is applied at this point, your road bike’s chain will struggle to change. As it attempts to move up and down to make the shift, it will get damaged by the cogs.

To ensure that you pedal properly, you must listen to the sound it makes. Shifting should be very silent. So, if you hear a loud noise while shifting, too much pressure is being applied to the chain as it attempts to change gears.

Installing a new chain may also result in improper chain tension.  When a new chain is fitted, some links must be removed at first because most chains are too long to be installed directly. Longer chains are helpful as they can cater to several varieties of bikes.

However, if too many links are removed when installing a chain, a greater amount of strain will be applied to it when shifting to the largest gears on the cassette.

The Chain Gets Bent or Twisted

Sometimes, a chain can become unfit to use without even breaking. A chain will most likely get bent when it falls off the cassette. Thus, the chain can get stuck if it jumps from the largest cog and is squeezed between the cassette and the wheel’s spokes. This usually happens when trying to remove the chain, so you must be very careful.

Additionally, the chain may also get stuck in the rear derailleur guide wheels. The road bike’s rear derailleur shifts the chain through the cassette on the back wheel to engage the correct gear. Thus, if maintenance requires you to remove the rear wheel of the road bike, the chain may come off the guide wheels and get stuck in the derailleur. 

Attempting to free the chain too harshly may result in more bents and twists, causing further damage to it.

The Chain Is Worn Out

Although road bike chains are made of metal, they are still vulnerable to damage because they grow longer with wear and tear. The links themselves do not get stretched out. Instead, the pivots and roller bearings that connect individual links get longer. If you continue to ride your bike under this tension, the pivots and rollers will start to bend.  

A single chain consists of more than 100 links. So, even though an individual bearing’s stretch may seem insignificant, these small differences add up. As the stretching continues, the strength of these bearings decreases. Eventually, this may cause them to fall apart, and the chain links will become separate.

Bearing stretches might not be visible but can cause substantial damage and impact the performance of your road bike. Thus, it is important to get your chain checked for stretch frequently.

old rusty bike chain and pedal

Direct Impact On The Chain

Another reason that may cause a chain to break is a direct impact. Although this is highly uncommon, a direct and hard hit can damage the chain. The chain can lose its shape, get twisted out of shape, or break if you slam your derailleur into a rock, the edge of a ledge, or just hit the ground.

If this occurs, more than just the chain can be impacted. Before you resume riding, you should check the rest of the bike for damage in addition to mending or rebuilding your chain.

Damage that occurs to a chain may not always be visible. So, it is important to be able to tell when your road bike’s chain might need a replacement.

How to Tell If The Chain Needs Replacing?

Sometimes, your chain may be too damaged to get repaired. There are several ways to check whether your chain has reached this stage.

Measuring With A Ruler

You can check a chain’s wear and tear using a ruler. By putting some pressure on the chain for accurate readings, start at one link pin and measure 12 complete. On a standardized new chain, 12 complete links should measure 12 inches. However, when a chain is worn out, it will be longer, and then the 12-inch mark of the ruler will not measure the same as the new chain.

If the distance from the 12-inch mark to the middle of the link pin is less than 1/16 inch, your road bike chain can still be used. However, if the distance reaches the 1/8-mark, your chain is beyond the point of repair and needs a replacement.

Chain Wear Indicator

This is sometimes referred to as a chain checker and checks road bike chains for wear and tear. To use this, hood the curved end of the chain wear indicator onto the chain. If the gauge tip on the other end fits into a chain link, the chain is damaged beyond repair.

Measuring By Eye

This is the simplest method of checking your road bike’s chain for wear and tear. If you observe the chain to be too loose or bent, it is damaged and needs replacement.

If your road bike’s chain is too damaged, it must be replaced. However, chains can be repaired most of the time. Continue reading to find out how! 

How To Fix A Broken Chain Without Tools?

Numerous specialized tools can be used to repair a broken chain. However, most people do not always carry a tool kit with them and may need to fix their road bike chains while on the trail. There are some methods you can use to fix chains without tools.

You can watch this tutorial about fixing the chain as you read ahead: 

Fixing A Chain With Broken Or Twisted Links

Sometimes, road bike chain links break or get twisted because of high tension or direct impact. If you do not have bike chain tools when this happens, position your bike so its chain mechanism is at the bottom.

Then, look for any solid metal with a small hole in it. An example is a bicycle nut. Put the nut on a flat surface, such as a rock, to ensure stability. The next step is to find the damaged or twisted portion of your chain and position it over your bike nut such that the pin is directly over the nut’s hole.

Following this, place your nail in line with the pin and punch it. Be careful in doing this, as excess pressure may further damage your chain. Repeat the step on the opposite side of the faulty chain links as well. If you have a replacement chain link, you can add it here. Otherwise, you will have to work with a shorter chain until your bike chain is repaired.

Lastly, align the inner and outer plate holes and fix the pin with a hammer to connect your chain. The next method focuses on the road bike chain’s master link.

Fixing A Chain With A Broken Or Twisted Master Link

A chain master is a quick-release link that makes it easier to connect and disconnect chains from the drive mechanism without using a tool. As some master links are non-reusable, you may need to repair your road bike’s chain without them.

First, find the master link and hold it to isolate the link at the top. Then, use pliers to apply pressure on opposite sides of the master link to release the lock. Regular pliers or long-nose pliers can be used to remove the master link by twisting it.

Following this, get a similar replacement link for your road bike chain. Before reconnecting the chain, ensure that your chain has passed over the front chain ring. Finally, replace the new master link and pull the chain link apart. The master link lock will slide into its position, and you can start riding your bike again.

Although a broken chain can get repaired even without tools, it is important to prevent it from breaking altogether. Let’s delve into the nitty gritty of prevention! 

worn rusty bike chain

How To Prevent A Bike Chain From Breaking?

A road bike chain that suddenly breaks can be worrisome. While a snapped chain is less common when it comes to fixed gear bikes, it’s more likely to happen to road bikes. You want to prevent it from snapping and there are usually enough signs your chain is about to fail.

Replace The Chain Regularly

Getting your road bike chain replaced regularly can prolong its life. You should replace your chain every 2,000 to 3,000 miles, depending on your riding style. Although a well-maintained bike chain can last up to 8 years, it becomes inefficient over time because it wears out.

Additionally, pins and rollers in your chain can wear down as the grunge gets stuck to the chain lubricant. This increases the center-to-center distance of your chain. As the distance increases, your road bike chain will stretch beyond repair.

This means that instead of paying a lesser amount for a new chain only, you will have to pay a larger amount to replace the chain ring and cassette as well.

Clean the Chain Regularly

To ensure that your road bike chain lasts long, it must be cleaned often. After a hard impact, any remaining chunks of dirt attached to the chain can also break it. They can also damage the cassette and derailleurs. 

Chains can be cleaned by wiping them down with a clean cotton cloth after every ride. You can also buy a degreaser to clean the chain. A nylon brush can be used to scrub the chain with hot water and liquid soap.

However, if your bike is too dirty to be cleaned on your own, you must take it to the local maintenance shop. After the chain is cleaned, be sure to dry and lubricate it before taking it out for a spin.

Examine Your Bike

It is vital to inspect your road bike before every ride. Look out for any dents, misalignment, loose pins, or stuck pebbles that got missed during the cleaning. Ensure that the chain remains tightened. To do this, remove a link or two and reattach the chain ends.

Assess the Way You Ride Your Bike

The way you ride your bike also impacts the life of the chain. Riding at a high tempo is more efficient and cost-effective. You should avoid cross-chaining. This refers to using small chain rings and small cogs or large chain rings and large cogs in the rear. Doing so will stretch out your chain faster.

Final Takeaway

In conclusion, numerous reasons can break road bike chains, including too much tension on the chains, bent and twisted chains, worn out chains, and direct impacts. 

However, there are several precautionary measures that you can take to prevent this. You can also look for signs of damaged chains and get them replaced before they break.