Cycling - Knowledge

Bike Maintenance: When to Replace Bike Chain (A Quick Guide)

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Love cycling? Well, that calls for a good maintenance of your favourite road bike for smooth performance. Regular inspection of the bike parts will ensure that you have a smooth ride all around the year. Regular maintenance of the bicycle will also ensure that life of the components is extended while sustaining the ideal drivetrain performance. Bike chains are one of the most important components of a road bike that needs equal attention. These chains wear with regular use and may lead to drivetrain concerns like “chain skip”. This occurs when you have been pedalling under pressure and the chain slips forward. This can occur due to many reasons, for instance, the chainlink stiffens up, or due to the fact that the freehub body has worn down. But the most common concern of all is the chain wearing and so, you need to be able to identify the time when to replace the bike chain.

It is believed that if we replace the chain before it starts to wear off badly, the life expectancy of the drivetrain increased remarkably. It can save you a lot of money in the long run. But, if you are a sportsperson and frequently participate in races, changing it every 1000 Km is a great idea as it reduces the risk of broke chain all of a sudden, and will also offer enhanced twist resulting in slow and sloppy shifting. So, if you are looking for a smooth shifting between the wheelsets, then you must be able to find out when to replace your bike chain. Let’s first understand the chain and other aspects in brief. 

The Pieces of a Chain

Many individual pieces like the inner plates, outer plates, pin, roller, and the bushing forms a bicycle chain. 

If you own a bike with latest fashioned chains you will find the bushing connected with the inner plate that holds the circular roller within. The arrangement is such that the each of the chains are joined with the next placed alternately between the inner and the outer plate.

The chain pitch has a space of 12.7mm between the pins. This space is the industry standard on a bike with multi-speed function. 

stretched bike chain symptoms
Chain Anatomy (source)

What is Chain Wear

The pins and the rollers are the micro components that hold the separate chain links together, wear over the period with a growth in the pitch of each link.

This wearing of the chain where the metal does not stretch, is usually called chain stretch. It’ when the inner diameter of the bushings increases in size and the pins cut through. A worn chain is usually believed to reach a growth of one percent from the original diameter 12.7mm pitch. 

Slop is another type of chain wear, however, it’s not easily measurable. This chain wears from side to side causing gradual and inconsistent drift much earlier than the pin wear is noticed. 

how often should i replace my bike chain
Worn out Chain (source)

Effects of Chain Wear

Poor shifting and loss of efficiency are the common stretched bike chain symptoms which will eventually make you think on when to replace bike chain. A chain that’s extremely worn is weaker and there is no use of that fractured chain with no power. When unattended for long, the chain wear can cost you a fortune. A new chain with a 0.5inch ditch is created so that it can sit properly in the depth of the wheel. 

As the size of the pitch stretches, the chain moves up higher on the tooth and results into a faster wearing of the cog/wheel. This is because there is a reduction in the point of contact. The longer you leave it unattended with the wear, the chain starts slipping from the top of the wheel. Even a worn chain used on a new cassette can wear out the cassette in no time. The main function of the chain is to match the gears with the chain pitch, and hence, replacing it even before the chain is worn out will help the chainring and the cassette gear last longer. 

Chain Types

Before we get into when to replace bike chain, it is essential to know the various chain types. There are majorly three types of chains. The only difference between these chains is in the way these are replaced. Carrying a chain tool while riding your bike will help you out of tricky situations. 

Type 1. Chain Joined with Special Replacement Pin

A special pin is inserted on this chain that replaces the stock pin. This the same technique on which the latest chains Shimano and Campagnolo works on. The new chain is accompanied with the special replacement pin. Sometimes even two can be there so be careful when you open the package and don’t lose it. 

chain wear tool how to use
Replacement pin for chain (source)

Type 2. Chain joined with Special Connecting Link

The master link or the special connecting link has two outer plates with pins sticking out that are added into the chain rollers, adjusted to fit together and then tightly blocked by pressing on the pedal. This link is joined with the chain. It comes with the new chain so, find it in the package.

how to check bike chain wear
Chain join (source)

Type 3. Chain joined by Any Pin

Usually the chain is joined by pushing any pin out to the extent so that it stretches the chain to isolate the ends. While the modern chains use the special pins or links, it is better to have this concept clear in case your chain is broken midway and you are not equipped with a replacement link for repair. 

park tool chain checker cc2
Chain joined by pin (source)

When to Replace Bike Chain

With increasing miles, the bike’s chain, internal parts of the chain (rivets and rollers) starts wearing out and looks like as if it’s stretching. 

This erosion can result into the chain to link badly with the cogs and can even lead to slipping over the cogs. So, if you want to avoid spending a fortune on replacing the cassettes, then it’s better to replace it even before it wears out. So, how do we measure the chain wear before we replace the same? Let’s see..

How do I Measure for Wear

Wondering how to check bike chain wear? We can use different methods that include either a chain checking tool, or a ruler. Although it is much of a debate as to which is the best method, you can use the one that’s convenient for you. 

Method 1: Lift Off Chainring

The first way to find out the extent of chain wear is to just pull the chain up from the front chainring. Move towards the shortest cog wheel at the back side and the largest chainring in the front, and then pull the chain out from the chainring. If you notice a lot of space between the chain and the chainrings allowing light to pass, then it’s time you replace your chain. This method is almost as accurate as measuring it with a real tool. 

chain stretch tool

Method 2: Measure with Ruler

Another best way to check the extent of chain wear is using a ruler to measure. Select a rivet to line it up at the zero point. Now count upto 23 rivets more and the last one should measure 12inches on the ruler. If the chain stretch is off by 1/16th and above then it’s the right time to replace it. 

chain wear indicator instructions

Method 3: Use CC-3.2

CC-2 and the CC-3.2 are the two types of chain stretch tools that are especially designed to measure the extent of chain wear. Find the end of the tool (CC-3.2) to begin measuring the chain wear using the o.5 amp. Fix the end of the hooks on a link featuring the inner plates. This will ensure that the measurement is done against the roller instead of the side plates. Now, try to fix the other end into the chain. If it does not get into the chain towards the end with 0.75 percent, it signifies that your chain not yet 0.75 worn. 

If the reading is more than 0.75 percent on the CC-3.2, it means that your chain needs to be replaced immediately. If the chain you are using is made for ten gears, or less, you must replace the chain as it closes the 0.75 mark. If it’s ten or 12 speed chain in use then the chain must be replaced as it reaches the 0.5 mark. For the two or single speed bikes, you must replace the chain as it reaches the 0.1 percent mark. 

how to use a chain checker tool
 CC -3.2 Measure Indicator

Method 4: Use CC-2

Take the CC-2 chain tool and place it inside the rear stud that’s positioned between the two outer plates and front beam between the two inner plates. Slowly press the lever to move out of the chain and check where it reaches the point. Make sure that you do not force the tool after the stopping point is reached. You can imply read the extent of wear of the chain in the window.

What is the Best Chain Checker

There are a number of views on which chain checker actually works and that can read the wear off sign pretty ahead. Passionate cyclists often debate the fact that chain checking tools are prone to offer false measurements considering the roller movement by pressing the chain pieces in the reverse direction. 

If you are using a chain from the Shimano or Pedro’s brand then you would notice that these separate the roller wear with the help of measuring pin wear in the similar direction. These are believed to be really precise across all speeds (from 6 to 11) and chain brands. There’s actually only one magnitude universally that’s agreed by all that is, the pitch from one pin to the next (0.5 Inch). 

The diameter of the rivet pin, the diameter of the roller both inside and outside, the diameter of the pit in the inner chain plate where the pin passes through, and the amount of space between the pin and the plate, and between the plate and the roller can differ a lot for different models. Most of the chain wear tools help you gauge the length of the chain in addition to the thickness inside the roller, which is over and above the dimensional variation as a part of the chain design. 

How to use a chain checker tool? The readings on many chain wear tools can be confusing as they might display the length in millimeters, percentage wear, or percentage stretch. So, when a tool indicates that the chain should be replaced at the 0.50 mark, it could be well indicating any of three parameters. 

Readings are also highly affected by the roller movement. While some chain wear checkers cannot differentiate between the roller movement and the pin wear, there are many tools those can effectively read when the chain is worn and can cause damage to your cassette. 

chain stretch chart
Different Chain Checkers (source)

How Often Should I Replace My Chain

It is to understand that the riding miles will not tell you accurately when you need a replacement, but keeping a regular check on the measurement will. So, finding the chain wear with distance is basically not possible. There are a quite a few variables that are to be considered. One can buy the drop-in style chain wear tools that are available at much lower cost. You can use this once in every few weeks as part of your maintenance. You can also invest in chain checkers from brands like Park Tool, KMC, Abbey Bike, or SRAM that read the chain wear at 0.5 percent mark and indicates that you need a replacement before the damage of the cassette. Learn the easy troubleshoot techniques for your bicycle and never stay stranded on the road!

Purchasing and Sizing the Chain

Once you know that you need a replacement for your chain, make sure that you remove any pin out of the chain using a chain tool. If the tool features two grooves to hold the chain ensure that you rest the chain so that your pressing against the stronger one that’s normally at the back of the tool. This is critical to remember as you may end up breaking the tool if you rest the chain on the centre groove and try to move the pin out. 

Once you have removed the pin from the chain, you can now remove the chain from the bike. Now you can count how many links are present on your chain, or you can take to a mechanic and let them do the needful. So that the chain works properly on your bicycle you must ensure that length of the new chain must be the same as the old one. It is better to use the same variety of chain as earlier that worked on your bike. For instance, a 10-speed chain should be used with a 10-speed drivetrain, and so on.

Routing the Chain Through the Derailleurs

Once you have a new chain of the right size for your bicycle, you can now go ahead with the installation. You need to firstly route it through the derailleur at the back by letting it go below the lower pulley, then up towards the right end of the top pulley, and then towards the rear and on top of the cassette. Here you must ensure that the chain does not sit anywhere else except the pulleys forming a reverse S where it goes through the pulleys. 

Now, the chain should be pulled towards the front of the derailleur cage and should circle the lower bracket. The chain should eventually sit on the frame and not on the chainring. 

Joining the Chain

One should be extremely careful while installing the pins while you are repairing or installing a chain, because most chain failures are due to one of the pins being incorrectly installed. The latest chains are extremely slim and so, if any of the pin is that is not adjusted properly where it rests in the outer plate may lead to chain breakage. Always make sure that the pins are aligned in a way that all of them protrude in equal lengths. 

You can also use a special connecting link and not the replacement pin in case you are not comfortable with pushing the pins in and out. All you need is a pin that matches with the size and type of the chain. 

Repairing Techniques

Repairing A Bent Chain

When you feel that there is a roughness during pedalling or frequent skipping, that is when you know that a certain portion of the chain is bent. This can occur if a stick is caught at the drivetrain and you still continue pedalling without any knowledge.

You must stop pedalling and look for the damaged section by backpedalling to repair it using your hand while you watch the bad links pass through the derailleur pulleys at the back. Make sure that the bad links are prominent while they pass over the pulleys.

Now, pull the chain back to find the damaged section. Hold the chain on any one of the sides of the bent link to repair and twist. Make use of hands or pliers that’s nearby and with light pressure you can straighten the bent spot that’s enough to help you move. 

how to check bike chain wear
Bent Chain

Repairing A Broken Chain 

If you have installed the pin incorrectly, it may lead to broken chain. The best way to avoid damaging chains is to follow the installation instructions carefully. However, in case where the chain is already broken you can make use of your chain tool to extract the link that’s damaged and the reconnect the ends of the chain. You can also trim the rollers otherwise so you will be left with a roller on one side and an outer plate with pin on the other side. You can also make use of a special replacement pin to rejoin the links. Alternatively you can also join the chain with a wire piece or a string that you may find on the road. 

chain stretch tool
 mend a broken chain

So, if you want a happy ride all around the year, it’s important to maintain your bike and keep a check on any damage before it’s too late to replace the chain. We hope this post helped you understand when to replace your bike chain and how to maintain your bike in good condition.

Happy riding!

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