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How Tight Should A BMX Chain Be? The Perfect Chain Tension

broken BMX chain

A BMX bike is for people living at a faster pace than others do. With the swift movements and stylish tricks, a BMX bike depends a lot upon its chain. If the chain is too loose, the parts won’t function properly, and if the chain is too tight, all the movable parts in that BMX bike will wear before time. Therefore, it is crucial to apprehend how tense your BMX’s chain should be.

Your BMX chain’s tension is measured through the vertical deflection. If the aberration is more than half an inch, it could jiggle out of the chainring. You do not want your BMX chain to bounce off; hence, a BMX chain should allow only a deviation of ½’’.

Let’s dive a bit into this subject a little more and learn why the right tension matters.

BMX Chain Tension

A BMX chain helps you propel your bike forward, and it depicts the rate of power transfer. If chain tension is appropriate, the quality of power transfer will remain vigilant. Therefore, a BMX chain should be tight enough with a small vertical deflection.

People with second-hand bikes typically face this problem of loose chains more often than newer BMX bike owners. However, it is not entirely unusual for a new BMX to have a chain that is not appropriately tight.

If you are new to BMX bikes and you are still into the learning phase of BMX maintenance, you do not typically realize whether your bike parts are in top-notch condition or not. When there is slack in the bike chain, you could think there is a problem with pedals or the crank area; still, it might just be a loosened chain. So, one needs to understand how loose a BMX’s bike chain could be?

As discussed above, the bike chain should not have a vertical deflection of more than a half-inch. An inappropriate bike chain’s tension could lead to various consequences.

BMX Chain Tight or Loose?

bmx chain close up

Some bike riders like to keep the bike chain too tight, and it makes the cranks hard to spin, while others leave it wobbling a little too much that it comes off. How do you find the right balance? The answer is: keep the chain at a moderate level.

A BMX is in the right condition if the bike chain never hits the chainstay. With that in mind, you can determine how tight or how loose the BMX chain can be. Still, if you aren’t sure, you can slacken it by 2 mm and notice the difference.

If your BMX chain is too tight, it will create a rattling sound. This noise could not only be awkward for your viewers but also could prove to be dangerous. To avoid that sound, you should play around with your bike chain to see what works. If the chain position cannot be altered (due to the smaller frames these days), just visit your local bike shop to have it fixed.

There is some personal preference involved when it comes to chain tightness but there are limits. The technical aspect can’t be ignored. If you are the kind of rider, who likes to spin a lot, you should have the chain wobbled by a couple of millimeters.

What Happens if Your Bike Chain Is Too Loose?

So what happens when the bike chain is too loose? Well, if you think the chain has slackened a little you’ll probably notice, it will bounce out off the sprockets or chainring. No biggie, unless you’re about to get gnarly.

You wouldn’t want your chain to fall off while performing stunts, BMX is a pretty gnarly sport and if you can, avoid injuries that could have been prevented.

On the bright side, if your bike chain is a little loose, you do not need to pedal hard. Because, if the chain were tight, you would need to pedal a lot harder. Still, the “positive side” does not mean your bike chain should be too loose.

If your bike chain is uncomfortably loose, it can entirely fall off when pedaling swiftly or jumping high on your BMX. Moreover, as a consequence, the power transfer rate will drop. When you feel that pedaling your BMX will not bring you the desired speed, you should check your bike chain.

If the chain is too loose, you should stop riding and give it a fix, or you might not reach your destination in time, or the fun ends right then and there. On the contrary, if you feel that the BMX chain is not “too loose,” you can continue your journey and treat it as a non-urgent matter.

What if Your BMX Chain is Too Tight?

Firstly, when a BMX chain is tighter than usual, the cranks on your bike will be hard to turn. It could be a result of grinding. BMX bikes suffer quite some abuse, and are put to the test when you’re performing the stunts. These tricks could result in a hardened crank. Moreover, it could also be caused by dirt and wear of use.

If you face this problem, loosen the chain by the margin of a hair, and see if it works. With the loosening of the chain, the cranks should not be hard to turn anymore. You’ll probably find your ideal tightness by trial and error.

Secondly, a chain too tight will result in abrasion of the other parts associated with the bike chain. This means those parts will wear faster which can be expensive. Inspect your bike occasionally to prevent parts from wearing.

Why Does My BMX Chain Have a Tight Spot?

A tight spot on a BMX chain means when the entire chain is loose, but there is a specific tight spot. It is not uncommon for a new bike to have a tight-spot in its chain. If you feel your BMX chain has a “tight spot,” the first thing you should check is the Sprocket.

This tight spot on a BMX bike is usually caused by the bolts behind the Sprocket being loosened. A simple tightening of the bolts should fix a tight-spot. However, if you cannot fix the tight spot, it is best to get it replaced.

What Are BMX Chain Tensioners?

BMX chain tensioners are something widely used in present-day cycling sports. One would manually tighten the bike chain in the old days by playing with the bolts and the wheel. However, BMX chain tensioners are commonly used now to prevent forward-slipping when a biker is pedaling hard.

These chain tensioners help your BMX chain to be easily set to the “right tension.” It is safer to use and acts as insurance against slipping in the forward motion due to hard pedaling. It keeps the wheel in the center of the frame.

BMX Chain tensioners give you two primary benefits:

  1. It keeps the chain tension corrected. The bike chains will never be too loose or too tight if your chain tensioners are working correctly. These also wear with time and bend after a lot of grinding, so you need to keep them in check.
  2. BMX chain tensioners keep the wheel centered. As a BMX bike owner, you would know the struggle of checking the alignment of your wheels to keep them perfectly centered. Now, with the use of bike chain tensioners, the problem is solved.


BMX is a great excercise, but safety is important and so is maintenance.

A BMX chain should be just the right size. It should not be too loose that it touches the chainstay; neither should it be so tight that the cranks become harder to turn.

Inspect your chain and other BMX parts regularly to prevent accidents and unnecessary maintenance costs. It’s not just your chain that needs to be replaced if you mess up which can be quite expensive.