Bike chains are prone to wear. So, it doesn’t surprise that you may need a chain replacement after some years of usage. In that case, you’ll ask, ‘what size chain do I need for my BMX bike?’
The standard BMX chain length equals 96, 98, or 112 links, while its width is either 3.2 mm or 1/8 inches. However, there are narrower and lighter options with a width of 2.4mm or 3/32 inches.
So, when getting a replacement BMX chain, you should consider both the length and the internal width. Most likely, you should consider the length and width of the original chain when getting a replacement.
This guide will take you through how to size your BMX bike chain and fit a replacement chain. We’ll also examine why you should replace your BMX chain and some FAQs on BMX chain sizing.
Let’s get started:
What Size Chain Do I Need for My BMX Chain?
When getting the correct BMX chain, we usually consider two significant parameters – the length and the internal width. Let’s elaborate them further below:
a) The Chain Length
Any bike chain length is measured in links. The standard BMX bike chain has links that range from 96, 98, or 112 links. Anything that does not fall within these three is not considered standard.
So, when getting a chain for a replacement for your BMX bike, it’s always a good idea to manually count the links of the old chain to get the length correct.
b) The Chain Internal Width
This is the commonest parameter used to determine the chain of your BMX bike. The internal width is usually the plate’s spacing.
The standard BMX bike has an internal width of 1/8 inches, equivalent to 2.4mm. There are also some other options with 3/32 inches (2.4 mm) and others with a width of 3/16 inches (4.88).
The former is skinnier and primarily meant to save on weight, while the latter, though uncommon, is strongly built but heavier than the two.
How Do You Size A BMX Chain?
Below are helpful ways to size your replacement BMX chain:
a) By Using the Original Chain
If you still have the original chain, you can use it to determine the chain replacement size. You can do this by counting the links. Keep note that the standard BMX chain has links of 96,98, or 112.
You can also align the old chain with the new replacement chain and place the master link in the rivets. That will help you solve the puzzle of what size BMX chain you’ll need.
But what if your original chain is worn out, damaged, or stretchy? What if you don’t even have the original chain with you?
The length will be misleading and for this case, proceed to the calculation method discussed next.
b) Use The Calculation Method
If you feel like manually counting the links is a doubting task, or you don’t have the original chain, you can use this method to get the correct BMX chain size.
You can use the formula:
L = 2(C) + (F/4 +R/4 + 1)
Where:
L = Chain length
C = Is the length of the chainstay (in inches)
F = Is the teeth number on the front sprocket
R = Is the teeth on the rear sprocket
So, you need to know the number of teeth in both your front and rear biggest cogs to use this formula efficiently.
When Should You Replace Your BMX Chain
Now that we have seen how to get the correct BMX chain size for replacement, the next question we should answer is when you should replace your BMX chain.
The circumstances include the following:
1. If Your Chain Is Worn Out
All bike chains wear with time. So, if you have been with your BMX bike for years and have hit at least 2,000 – 3,000 miles, your BMX chain will start wearing out.
To help you determine the degree of wear of your BMX chain, use a chain checker like the CC-4-Chain Wear Indicator (View on Amazon) shows you the degree of the chain stretch. The good news is that you can also use it on other bike chains and not just BMX.
Remember, when the chain wears, it will also damage other parts of the cassette, which can be expensive to repair.
2. If Your BMX Chain Keeps Snapping
If your bike has been in use for a couple of years, the chain has stretched over time. That means that the chain will keep skipping when pedaling and won’t fit properly in the chainring.
One reason behind a stretchy BMX chain is wear. So, if you have been with your bike for too long, it’s time to change the chain.
3. If Your Chain Misses Some Links
As highlighted earlier, the standard BMX bike chain should have links of 96, 98, or 112. If you suffered an accident recently, the chances are that some of the links to your BMX bike are missing.
So, if you manually count the link and find missing some, you should change the chain before it’s too late.
How Do You Fit A BMX Chain?
Now that you are sure your bike needs a chain replacement and have a new BMX chain with you, how should you do it?
First, you need to have a new BMX chain.
Steps of Changing A BMX Chain
- Detach The Old Chain
The first step is to remove the old BMX chain. All you need to do is to loosen the bolts of the axle. Doing this will make the chain loosen and sag.
To aid in the successful removal of the chain is a chain breaker. However, you need to use it carefully not to break or damage the components of the cassette.
- Check The Chainring and Cassette
It’s always advisable to check the chainring and cassette to ensure that they are in excellent condition before installing the new chain.
If the chainring teeth are worn out or bent, they will damage the chain. If you notice bent teeth, you can consider calling a bike expert to help you fit the chain but if they all seem okay, proceed to the next step below.
- Measure The Chain Length
Now that you have both the old and the new chain with you, measure the length of the new chain you will need. You can do this by laying both the new and the old chain together.
If the new chain is long, you can use a chain tool like the Birzman Damselfly Universal Chain tool (View on Amazon) to detach the extra links you won’t need.
- Place The New Chain
Once you have the correct chain length, it’s now time to attach it to the chain wheel. So, place the chain on the chain wheel, ensure you join the two ends and tighten them slowly.
When at it, ensure that the chain is not too tight or too loose. Lastly, tighten the axle nuts and spin the rear wheel to check if the chain is in the correct orientation.
People Also Ask
1. What Size Chain Do I Need for My BMX Bike?
Determining the size of a BMX bike chain is not rocket science. You need to count the links of the old chain manually. The links should be either 96, 98, or 112.
Still, when you get the links correct, you also need to determine the internal chain width, which should be 1/8 inches for the standard BMX bikes.
2. What Is the Standard BMX Chain?
The standard BMX chain usually has an internal width of 1/8 inches (3.2mm) and comes with a standard length of either 96, 98, or 112 links.
3. Are BMX Chains Universal?
No! BMX chains are not universal. Though standard options have an inner width of 1/8 inches, they can vary in length where some have 96 links, others 98, and still some have 112 links.
4. How Can I Know the Length of My BMX Chain?
The length of your BMX chain is determined by the number of links the chain has. Standard BMX chains have 96, 98, or 112 links. You need to remove the chain and manually count the links to get the correct length.
What Size Chain Do I Need for My BMX Bike? Closing Thought
There you have it! When buying a new BMX chain, you should get the width and the length correct next time. The standard options have an inner width of 1/8 inches and a length of 96, 98, or 112 links. Anything beyond this is not standard.
However, we also have chains with an internal width of 3/6inches and others with 3/32 inches. So, know where your BMX chain lies.