How Tight Should A BMX Chain Be?

As small as they are, BMX bikes are some of the well-made two-wheelers without which stunts and tricks such as suicide no handers, bunny hops, and no footed cancan would be impossible. For smooth and efficient movements, even at short bursts of speed, the BMX chains need to have the right tension. But how tight should a BMX chain be?

A BMX chain should have just the right tension. If it’s too tight, the crank will be difficult for the rider to turn the crank, and the movable parts will wear out quicker and demand costly replacements. Too loose and it unnecessarily touches the chainstay, which makes efficient riding difficult.

Manufacturers and bike mechanics measure BMX chain tension by the means of vertical deflection. An aberration that’s more than half an inch can easily go out of the chainring, leading to the bouncing off o the chain.

If anything, you need to make sure that the chain of your BMX bike has a deviation of at most half an inch.

BMX Chain Tension: Understanding The Basics

A BMX chain is the bike component that determines the rate of power transfer every time you pedal. And it’s the means through which you propel the bike forward.

You can’t make the chain too tight or too loose. The tension has to be on the right level so you can get a more optimal level of power transfer as you ride the bike. 

Some roadies argue that riders that have second hand BMX bikes tend to deal with loose chains a lot more than those who have newer model. Yet even new BMX bike models can become subject of loose chains that make optimal riding quite difficult.

I should mention that a loose chain isn’t an indication of a faulty BMX bike At the very least, the issue isn’t with the crank or the pedals, because you’re more than likely dealing with just a loose chain that needs tightening.

The most important thing to remember when it comes to handling your BMX bike’s chain tension is that there should be a vertical deflection of not more than half an inch.

Should A BMX Chain Be Tight?

A BMX chain shouldn’t be too loose or too tight. You need to make sure the tension is at the right level, or the bike can be difficult to ride and navigate.

bmx chain too tight

Quite too often, high-tension BMX bike chains aren’t easy to spin, and that means pedaling the bike with ease can be just as hard. Loose chains, on the other hand, can easily wobble, and sometimes do so too much, that it easily comes off.

It doesn’t end there.

Tight chains cause BMX bikes to make noise. The rattling sound coming from the chain can make your look rather awkward and it can be equally as dangerous when riding the bike.

So the question then is:

How tight should the BMX bike chain be exactly?

The tightness of the BMX chain should be at a moderate level. That way, you won’t have to worry about it coming off as you pedal or feeling unnecessarily too tight to make your riding difficult.

Test the BMX chain to make sure it never hits the chainstay. It helps to tighten to slacken the chain by at least 2mm to see if that can make a difference.

It’s tasking to alter the chain position of some BMX bikes, and that’s mostly because they have smaller frames. Should this be the case with yours, visit a bike shop near you to have the bike fixed.

How Do I Know If My BMX Chain Is Too Tight?

The best way to know if your BMX chain is too tight is by wiggling the chain up and down. If the chain is set to the moderate level, you’ll feel the resistance as you pedal the bike.

Move the cranks to exactly where the chain feels tightest, turn the cranks a number of times to see if it’s still in the same position.

If you notice that the tight spot is on the same place whenever you pedal, there’s a high chance that the problem is with the front sprockets. If the tension changes whenever you pedal, there may be a problem with the rear sprocket or the chain itself.

As you run this experiment, you’ll notice that the righter the chain is at different points, the more leg power you need to turn the crank.

Another problem with a tight chain, and one that may not be immediately obvious, is the abrasion of other parts of the bike that the chain contacts. And given that the wearing out tends to happen faster, you’ll find yourself replacing the cranks and sprockets more times than you can count.

Of course, the cranks can get as hard because of putting the bike to rigorous use and a lot of abuse when performing tricks and stunts. It could also be because of continuous use or dirt.

However, the tightness of the cranks is because of over tightening the chain, which means that human error is strongly at play.

Cranks that feel difficult to move should not be difficult to deal with at all. Try to loosen the chain by a margin of hair and you’ll notice that the cranks aren’t that hard to move anymore.  

Why Does My BMX Bike Chain Have A Tight Spot? 

This isn’t such a common issue on a BMX bike chain, but it can be such an inconvenience to a rider if it occurs. If the chain has a tight spot, it means the setup is loose, but there’s one spot that generally feels tight.

More often than not, a tight spot on a BMX chain is an indication that the bolts behind the sprockets are loose.

Simply tightening these bolts should be enough to fix the problem, although a more serious case may require a complete replacement of the entire BMX chain.

Can My BMX Chain Be Too Loose?

Your BMX bike’s chain cannot be too loose because that, too, hinders the performance of the bike.

MKS BMX 10 Chain Tensioner

From a performance standpoint, you’ll notice that the chain bounces off the chainring or the sprockets if it’s loose. Not to mention get close to the chainstay. 

In theory, it may not seem like a big deal that the chain of your BMX bike is loose. In practice, a loose chain can be quite dangerous when performing advanced stunts.

Yet given that BMX is a gnarly sport, it’s best to ensure the chain has the right tension to avoid unnecessary injuries.

We can argue that at times a loose chain is a good thing. Well, that’s true to some degree, at least only to the extent that you don’t have to pedal harder to get the BMX to move at short bursts of speed.

However, that isn’t a reason to make your BMX chain loose.


It’s because the chain can easily fall off when pedaling fast or when doing high jumps. Even the power transfer rate will drop significantly, and that, in turn, makes it hard to attain a higher speed when riding the bike.

What’s The Best Way To Adjust BMX Chain Tension? 

You can adjust the tension of a BMX chain manually, but that can take a lot of time. The best way to adjust the tension of a BM chain is to use a chain tensioner. They not only make the chain adjustment easy, they also prevent forward slipping whenever you pedal hard.

Examples of the best chain tensioners designed to work with BMX bikes include:

MKS BMX 10 Chain Tensioner

These tensioners allow to set the BMX chain to the right tension and the safest bet when it comes to keeping yourself from slipping in the forward motion when pedaling.

Also Read:

What Chain Size for My BMX?

Final Thoughts: How Tight Should A BMX Chain Be?

There’s nothing worse than a BMX bike that won’t ride smoothly because of issues with the chain. That’s why you first need to make sure that the chain of the right size before you hit the street on it.

If anything, make sure the chain’s tension is on the right level. And as I’ve mentioned, the chain shouldn’t be too tight because it will make the cranks hard to move. And it shouldn’t be too loose because it can touch the chainstay and make bmxing difficult.