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Can you put a BMX hub on a mountain bike?

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BMX bikes and mountain bikes are two completely different pieces of equipment and they are built for two completely different uses.

With that being said, the components they use are similar even though they are built differently. That brings up the question, can you use a BMX hub on a mountain bike frame?

Eastern Bikes Freecoaster BMX 36h Ezra Hub, Matte Black
  • Weight – 16 oz
  • Right side drive
  • 3 options of slack adjusting discs sold separately
  • 9 tooth driver
  • Durable, hardened chromoly 14mm axle

It is possible to put a BMX hub on a mountain bike. You will need to understand that you might cause irreversible damage to your mountain bike by doing so. Also, you will need to start by filing your dropouts so that they become wide enough to fit the BMX hub and use spaces to align your wheels.

In this article, we are going to go in-depth regarding how you would put a BMX hub on a mountain bike. We are then going to discuss whether or not you should do this.

Finally, we are going to talk about whether or not doing this will cause damage to your mountain bike.

Can You Put A BMX Hub On A Mountain Bike?

We have already established that yes, you can put a BMX hub onto a mountain bike, at least in most cases.

You will find that some hubs are completely incompatible with a mountain bike frame.

However, if you do have a BMX hub that will make it onto a BMX frame there will be a few things that you need to do.

Because you are asking this question, we are going to assume that you already have a good amount of knowledge about wheels and hubs.

With that out of the way, here is what you might need to do in order to make a BMX hub fit on a mountain bike.

  • Widen The Dropouts On Your Mountain Bike
  • Use Spacers To Stabilize and align your wheel.
  • Fine-tune your spokes.
mountain biking down a trail

Widen The Dropouts

You can look at this in one of two ways. Either a mountain bike hub is built for a mountain bike frame or the frame is built according to the Hub. There is a standard and these standards get followed by manufacturers.

A BMX hub is 14mm in diameter while a mountain bike dropout is  12mm in diameter to accommodate a mountain bike hub.

So, you need to use a file to widen the dropout of the mountain bike frame.

I recommend using a file because even though it might take some time, it is a lot more accurate than using heavy machinery such as an angle grinder.

2mm on each side of the dropout is perfect. However, you can keep trying to fit the Hub into the dropouts while filing, this means that you can get the best fit.

Use Spacers

You will need to use spaces to stabilize and align your wheels.

Remember, the length of a mountain bike axle is different from the length of a BMX one and so, a mountain bike frame will be built according to the standards of a mountain bike hub.

Using spacers you can eliminate the problem of having a wheel that is not properly aligned or properly stable since the length of a BMX bike axle is different.

bike mechanice tightening spokes

Fine Tune Your Spokes

Now, you will still notice that your wheel is skew. So, to fix this you are going to want to fine-tune your spokes.

This entails loosening one side of the spokes while tightening the other. You will usually loosen the spokes that are on the driver side (The side that has the cog) and tighten the ones on the opposite side.

In some cases, this can be flipped but it is very rare. Remember, you are going to have to play around to find out which side you need to loosen and which you need to tighten.

Will Using A BMX Hub On Your Mountain Bike Cause Damage?

This is where I tend to have a problem with using parts that are not made for mountain bikes because, at the end of the day, you could end up causing a lot of damage to your mountain bike.

Trust me, buying a new hub is a lot cheaper than having to fix or replace the frame of a mountain bike.

Firstly, you will be damaging the dropouts. Remember we said that you will need to file the dropouts to fit the BMX hub? Well, this is permanent damage and you won’t be able to reverse it.

You could also be damaging your wheels, brakes, and chain line if you do not do a proper job of setting everything up.

You should always keep this in mind before doing anything to your mountain bike.

unpacking a new bike

Why Would You Want To Use A BMX Hub On Your Mountain Bike Anyway?

When you think about how a BMX rider uses their bike, it’s quite easy to understand why a lot of people have the assumption that the parts used on a BMX bike might be more durable than the parts used on a mountain bike. Well, this is not entirely true.

With that being said, a BMX hub can be built to withstand metal to metal grinding, absorbing the impact of big jumps, and they even have protective covers to protect the axle and the cog from being damaged.

So, a lot of mountain bike riders want to use a BMX hub on their mountain bikes.

You also get people that are known as tinkerers. There might be no specific reason other than the fact that they want to do it.

They have a spare BMX hub and they also have a mountain bike hub that is starting to be too damaged to do its job.

Another factor could be financial reasons. Someone might have a spare BMX hub and not have the money or not want to spend the money to buy a mountain bike hub and swap it for the damaged one.

cyclist jumping off with bike

How Important Is A Good Quality Hub?

If you bought your mountain bike as a complete setup then the quality of your hub will be according to the quality of that setup.

So, you might be thinking of getting a new Hub or replacing a damaged one with a new one. Does the quality of the Hub make a difference? The answer is yes, it absolutely does.

The first thing that a good quality hub is good for is durability. Spending more money on a hub can be financially better in the long run because you won’t have to keep replacing it.

A premium Hub will have the right amount of engagement points. Basically, what this means is that your bike loses less momentum every time it engages in a gear.

The engagement points actually play a significant role in the noise of the hub. A lot of people ask the question, why do more expensive hubs make more noise? Surely it should be the opposite, right?

Well no, the more expensive the hub is, the louder it will be. It means that the Hub is usually working harder than other hubs.

Another significant factor is less rolling resistance. This means that with a premium hub, you will have a smoother ride. It also means that you will get better performance.

mountain biker with a lake view


That is the end of this article and it is at this point where I feel that I can give my personal opinion. If you need a new hub for your mountain bike, it is better to buy one. Don’t use parts from another type of bike as this can damage the one you have.

If you want to replace your mountain bike hub with a BMX one because you think it will give you a slight advantage, I think it is better if you shell out around $400 for a professional mountain bike hub. That is still a lot cheaper than having to buy a brand new frame for your mountain bike.