An Easy Guide To Determine The Chain Length Of Your Bicycle

Are you a new bike owner who’s finding the technicalities of their shiny new ride a little intimidating? The most essential thing you should begin with is your cycle’s chain, more specifically its length. Now you must be wondering exactly how to measure a bike chain length.

If that is the case, then this article will walk you through the details.

How To Determine Bike Chain Length 

Correct Chain Length

Your chain is an integral part of your bike. It’s the central functional unit of your bicycle, followed by the wheels, of course. So ultimately, it is prone to some significant wear and tear. Bikes are composed of rivets as well as rollers. These components cause the chain to increase in length.

With the passage of time, as the rollers and rivets get used, they will stretch the chain and cause the length to increase. This can be a prominent marker of the age of a bicycle chain. 

So if you’re trying to determine if your chain is worn out or not, you should know how to measure a bike chain length. A shiny new bicycle chain is 12 inches long over 12 of its links.

If a chain does not comply with the above specification and measures somewhere around 12 1/16 inches over an exact number of 12 links, then it’s time to buy a new one.

Tools Needed 

Now that the need for a new chain has been established, the next step is to decide its specifications. These specifications aren’t too complicated. All you need to focus on is bike chain measurement.

The tools you need to measure the bike’s chain depend on the type of chain you have. These are of two types:

  1. Master Link Chain: This type of chain is connected by utilizing outer chain links for connection. These external chain links are removable.
  2. Connection Rivet Chain: As the name suggests for the connecting rivet chain, the connections are made by using rivets

The choice of tools is dependent on the above types of chains. These include:


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    • Chain Tool: To cut the chain for the purpose of size reduction
    • Master Link Pliers: Specifically designed to separate the chains containing master links

    E.g. Park MLP-1.2 

    Check & Remove Chain

    Chain Length Sizing

    A vital factor to note before you go ahead and dismantle the old chain from the bike is to make sure that it is of the appropriate size. If you’re new at changing bike chains and are wondering how to measure a bike chain, then this is where you should start from.

    First of all, you must shift your bicycle into maximum capacity chainring as well as a back cog. The primary test your chain has to pass is to be able to convey this particular shift with double minor bends at every back derailleur pulley.

    In the second step, you’ll have to shift over to the shortest chainring plus sprocket. During this move, there should be no lag or slack in the chain.

    In addition to this, the derailleur of your chain should be such that it doesn’t pull back to such an extreme where the chain comes into contact with itself.

    After this, it’s time for the removal of the back wheel. The purpose of this particular move is to relieve your chain of the tension that is being applied to it to provide you with better access to it.

    Once you have removed this, try to locate the master links on the chain. This is done to identify the type of chain you have. 

    Master Link Chains

    If you have appropriately identified and affirmed that the chain is a master link one, then it’s time to use the relevant tools to cut it. You could use a Park MLP-1.2 plier to reduce its length. This plier is specifically designed to deal with master link type chains.

    In another case where you might not have the Park MLP-1.2, and your chain has been subjected to sufficient wear and tear, you can just substitute this plier with a regular cutting tool.

    This will successfully separate your chain at the point where you need it.

    Connection Rivet Chains

    Connecting rivets are relatively easy to identify since they are visually unique in contrast to other members of the riveting family. One thing you need to be vigilant about is that if you are trying to separate a certain rivet, it should be spaced at a small distance from another preinstalled connecting rivet. Now insert the chain tool by bringing the driving tool of the chain tool into contact with the connecting rivet.

    At this point, the pin of the chain tool in question should be driving in an erect manner in the chain rivet for appropriate action.

    Apply force as you turn the handle to drive the rivet outward. Now all you need to do is remove the chain.

    Methods to determine chain length 

    Now let’s see how to measure a bike chain length. Its technicalities and different methods will be included in this part.

    Chain Length

    Method #1: Size to old chain (count links) 

    For sizing your new chain to an old chain, you need to make sure that the old one is of the appropriate size. Once you have verified the size of the old chain and deemed it appropriate, you can continue with the sizing of the new to the old.

    Align both your chains on a flat surface. When aligning the two chains in a parallel manner, make sure that the outer plates of the old chain are in line with the outer chain of your new one. Similarly, the inner plate of the old chain should be perfectly aligned with the inner plate of the new one.

    These steps are significant to get the exact measurement of your new chain. A good tip would be to utilize a master link here. Insert the master link For an exact and perfectly aligned side by side comparison of the two chains.

    Also, make sure to align the chains with respect to rivets because as time passes, the chain is destined to increase in length. This owes to the wear and tear it will be subjected to while being used.

    Method #2: Largest cog and largest chainring method

    If you’re changing your bike’s chains for the first time, there is a good chance that you discarded the worn-out one without realizing its usefulness. In this case, here is another method if you’re wondering how to measure a bike chain if you simply don’t have an old chain as a reference to compare the size of a new one with.

    To begin with, you will have to shift your front derailleur above the biggest chainring you can identify. Additionally, you will have to shift the back derailleur to the smallest cog.

    You will first have to wrap the chain around the largest cog, and this is done by passing the end of the chain from the frontal portion of the derailleur cage on the biggest chainring.

    Here you will hold it in the five o’clock position.

    In the case of a master, link install only half of this link. This will provide you with almost half an inch of extra length after this follow the same process as mentioned. 

    Just pull the lower portion of the chain to fit and then attach it to the front chainring. 

    Look for the nearest rivet where the two chain ends could be connected and use it as a reference, as this will be the point where you make the cut.

    Method #3: Chain sizing by equation

    The bicycle chains are technical as well as mathematical entities. They are composed of inner plates as well as outer ones. The chains are linked to each other when an inner plate comes in contact with an outer one. 

    This allows the chains to be connected at whole-inch increments. This means that a chain can be 53 inches (just an example), but it can not be 53-1/4″, or it can be 56 inches, but not 56- 1/2″.

    This makes it convenient to measure the chain by industrial drive train equations.

    You’ll first count the front teeth on the biggest front sprocket as well as the biggest back one.

    Secondly, you will measure the space from the center of the crank bolt all the way to the back axle. Now measure the nearest 1/8″, and change this to decimal form.

    Simple Equation

    Now use this equation for calculations: 

    Simple Equation: L = 2 (C) + (F/4 + R/4 + 1)

    • L = Chain length in inches 
    •  C = Chain stay length in inches 
    •  F= Number of teeth on biggest front chainring
    • R= Number of teeth on biggest back cog.

    The simple equation is the more frequently used one. This is the equation for the uncomplicated and straightforward chains.

    Rigorous Equation

    The chain lengths that have a relatively complex infrastructure of the chain cannot adapt the simple equation to provide the appropriate chain length. The reason behind this is the versatility of chainring sizes as well as the short dimension of the chainstays.

    Hence the rigorous equation is used for these chains.

     Chain Length = 1+0.25*(F+R)+2√(C*C)+(0.0796*(F-R))²

    • C – the chainstay length 
    • F – the number of teeth on the biggest front chainring
    • R – the number of teeth on the biggest back cog.
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