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What Chain Size Do I Need for My BMX?

What Chain Size Do I Need for My BMX?

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Most elements on BMX bikes are prone to wear and tear after years of use, and BMX bike chains are no exception. When this happens, a common question arises; What chain size do I need for my BMX bike?


When looking for a replacement chain for your bike, you’ll most commonly want to use the same width and length as the original, but in general, you’ll need to consider the internal width and length.


Through this guide, we’ll help you find out your BMX’s chain size and find the perfect replacement for it along with some reasons why you should replace the chain.


What Size Do I Need for my BMX?


As mentioned before, the two most aspects of finding the right chain size are the internal width and length:


Chain Length


The standard BMX chain length generally equals 96, 98, or 112 links, anything that doesn’t fit these aspects isn’t the standard. This is why when you’re thinking of getting a replacement for your BMX bike, it’s a good idea to manually count the old link’s chain to get the correct length.


Chain Length


The standard BMX chain width generally equals 1/8 inches (3.2mm), while some options are 3/32 inches (2.4mm) and others with a width of 3/16 inches (4.88mm). The first is skinnier and primarily meant to save on weight, while the other, although more uncommon, is strongly built but heavier than the remaining two.


How To Size Your BMX Chain?


There are several ways to find out the size so you can replace your BMX chain:


1- Use The Original Chain


If you still have the original chain, you can use it to find out the chain’s size for replacement. This can be done by counting the number of links, bearing in mind that the standard BMX chain usually has 96, 98, or 112 links. Aligning the old chain with the new replacement chain and placing the master link in the rivets will help you determine the needed BMX chain size.


But what do you do if the original is damaged, worn out, or stretchy? Or if you can’t find the original chain? In these cases, the original chain won’t be able to help, and your best bet is to use the calculation method mentioned below


2- Use The Calculation Method


If you don’t have the original chain or the task of manually counting the links is too time-consuming, the calculation method helps determine the correct BMX chain size using the following formula


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



L = Chain length
C = The length of the chainstay (in inches)
F = The teeth number on the front sprocket
R = The teeth on the rear sprocket


For this reason, you need to count the number of teeth in both the front & rear biggest cogs to get the most efficient outcome with this formula.


When You Should Replace The BMX Chain?


Now that we know the standard sizes for BMX bikes, let’s discover the different situations where you would need to replace the chain:


1- The Chain is Worn Out


BMX bike chains wear out with time, so if you’ve been using your bike for years and have hit at least 2,000 to 3,000 miles, the chain will start to wear out.


To determine how worn out your BMX chain is, a chain checker helps measure how much it has stretched and can be used on a number of different bike chains, not just BMXs. But keep in mind that when the chain wears, it also damages the other cassette parts and can be expensive to repair, so early care is important.


2- The BMX Chain Keeps Snapping


The BMX chain can stretch over years’ worth of use, this means that the chain will keep skipping when you pedal and won’t properly fit in the chainring.

Wear is one reason behind stretchy BMX chains, so you have to change the chain if you’ve been using your bike for too long.


3- The Chain Is Missing Some Links


Considering the number of links in a standard BMX chain is either 96, 98, or 112 if the bike has recently suffered an accident, there is a chance that some of these links may be missing. This is why you should immediately change the link if you manually count them and discover some are missing.


How to Fix A BMX Bike Chain


We’ve learned how the chains are supposed to be, how to size them, and what to look out for to replace them, now let’s see how to fix it provided you have a new BMX chain:


1- Remove The Old Chain


Firstly, remove the old BMX chain by loosening the bolts of the axle. This will make the chain loosen and sag. Chain breakers help you successfully remove the chain, but if don’t want to break or damage the cassette’s components, you need to use these tools carefully.


2- Check The Chainring and Cassette


It’s advised to check both the chainring and cassette to make sure they’re in good condition before the new chain is installed. If the chainring teeth are bent or worn down, it will cause damage to the chain. Call a bike expert if you notice any bent teeth to fit the chain properly. If everything’s okay, however, move on to the next step


3- Measure the Chain’s Length


If you have the new and old chains, you can measure the chain’s length by either laying the two chains together or using the calculation method.


4- Install the New Chain


After determining the correct chain length, attach it to the chain wheel, ensuring you join both ends and slowly tighten them. Make sure the chain is neither too tight nor too loose, then finally tighten the axle nuts and spin the rear wheel to check if the chain is in the right orientation.


In Conclusion,


Every bike is susceptible to breaking down due to wear and tear, so knowing the right length and width as well as when and how to replace the chain will not only save you from injury, but also from the expensive task of buying it too late.


With the right BMX chain size, strap in and ride on!

daily biker author
Jim D. Smith
Biker and content writer at Daily Bikers Blog. Addicted to Bikes, aviation, fragrances, sushi and tacos.
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