BMX Bike Size Chart (Complete Guide) - The BMX Dude (2024)

Are you also asking yourself, “What size BMX bike do I need?”

It’s a very common question, so you’re not alone.

But wondering about getting the right size is a good thing.

Why?

Because choosing the correct bike is one of the most important decisions you’ll make.

The right BMX bike size will help you progress faster. But, unfortunately, it’ll do the exact opposite if you get a bike that’s too small or too large.

This post covers:

• How Are BMX Bikes Sized?
• Sizing Up Or Sizing Down Your BMX Bike
• Problems Caused By The Wrong Size BMX Bike
• Conclusion: Pick The Perfect Sized BMX Bike

However, when it comes to bikes with 12″ to 18″ wheels, the size isn’t as crucial as it is for 20″ bikes.

But regardless if you’re getting it for your kid or for yourself, read along to find the perfect size.

How Are BMX Bikes Sized?

BMX brands use two main sizing specs: wheel size and top tube length.

While bikes below the 20″ wheel size don’t vary in geometry much, you can get very specific 20″ wheel BMX bikes – for the style of riding you like to do most. Like these ultimate BMX street bikes.

The other geometry specs you should pay close attention to if you are looking for a more specific bike are head tube angle, chainstay length and bottom bracket height.

What do these mean?

• Head tube (HT) angle: A mellower HT makes the bike more stable and a steeper HT more responsive. (Anything above 75-degree is “steep.”)
• Chainstay (rear end) length: If you want your bike to be easier to spin, whip and even just manual, then a chainstay (CS) of 13″ (or below) will do the trick. But if you need stability, go with 13.5″ or even longer CS.
• Bottom bracket height: There are bikes with higher (makes the bike more responsive) and lower (makes he bike more stable) bottom bracket (BB) height. It’s a vertical distance from the ground to the center of the bike’s bottom bracket shell.

There are also head tube height, standover height and seat tube angle but these aren’t as important.

But I do like bikes with a higher standover height because it gives it a more classic look. However, a low standover height comes in handy if you’re a park dude doing a lot of tailwhips.

BMX Bike Size Chart By Height & Wheel Size

What about BMX bikes that are larger than 20″ wheeled ones?

While 22″, 24″, 26″ or even larger “BMX bikes” can fit a variety of riders’ heights, I recommend them only to taller dudes (5’8″/5’9″ and taller) because they feel much more comfortable.

Especially if you want to do tricks on them.

Sizing Up Or Sizing Down Your BMX Bike

Okay, so you’ve used the BMX bike size chart to find a bike that matches your height, but you’re right on the edge.

What to do?

Should you go up one size or down?

It all depends on the riding style you do, but also your age, because you might still be growing.

Here’s what I recommend you do.

Why Sizing Up

If you’re still growing and you don’t know whether to pick a 16″ or a 18″ wheeled BMX, go with the larger one.

You might outgrow the smaller one TOO quickly, so it might even be you wasting money on a brand new bike.

Hey, you’ll then need to buy a new one before you even get the proper feel of the current one.

But if you are already tall enough for a 20″ bike, sizing up might mainly relate to the riding style you want to do.

If you want a more stable bike because you enjoy riding fast and hitting trails and transitions primarily, then sizing up will make the most sense.

But even if you do decide to pick the smaller version, you can make your bike feel larger and more stable by stretching out your rear wheel, making the chainstay longer and getting a longer BMX stem.

The stock stem might be 50mm but you can get a 57mm, which will make a big difference.

You can even put your handlebar in the Chicago position (putting it forward, so it’s not in line with your forks).

Plus, you can get BMX forks with longer offset. (Don’t miss my complete beginner’s guide on BMX fork offset.)

Why Sizing Down

I’d recommend sizing down when you’re in between sizes only to those who are looking to purchase a 20″ wheeled BMX bike.

Anything smaller, always go size up.

Like in the previous case, it all depends on what type of riding you’re into.

If you like technical street (and park) riding, then going down one size will be better.

Why?

Because a smaller bike will be much more responsive, which is essential for all the spinning tricks, manuals, nose manuals and other technical wizardry you’d like to do.

However, if you feel like the larger bike will fit you better, here’s what you can do to make it more responsive and twitchy:

• You can slam your back wheel to make the chainstay length as short as possible.
• You can get a shorter stem.
• You can get forks with a shorter offset.
• You can put your handlebar in line with forks.

Ask For A Test Ride

If you aren’t ordering your bike online but will purchase it a your local bike shop, ask for a test ride.

This doesn’t mean they will allow you to jump or do any tricks, but just to pedal around (usually in the store).

The store owner will also help you with choosing the right size, thanks to their years-long experience.

Problems Caused By The Wrong Size BMX Bike

As someone who has been riding BMX for 20+ years, I can easily spot who’s on the right and who’s on the wrong-sized bike. I don’t even need to follow the BMX bike size chart.

And you will, too, after a while.

Whether you end up on a too small or too large bike, you won’t have as much fun and – worst-case scenario – be more prone to getting injured.

That’s why it’s worth spending some extra time examining the bikes and NOT make any urgent decisions.

But you can also reach out to me and I’ll be stoked to help you out.

A wrong bike setup can cause aches and pains but it can also slow down your progression.

For instance, if you have a too small bike, you’ll be a lot more hunched over, which can cause lower back pain.

With a shorter bike and a shorter chainstay, you’ll be easy to loop out that can cause nasty slams on your back (and even hitting your head – wear a BMX helmet!).

And if you get a bike that’s too big, it’ll take you a lot more effort just to pull it into a manual.

The bike will also be a lot harder to spin and it’ll be tougher to control it – it’ll more likely control you.

Conclusion: Pick The Perfect-Sized BMX Bike

While there’s a lot of stuff you need to consider when choosing a BMX bike, this guide will definitely equip you with enough background to pick the right size.

You also need to know that each bike FEELS slightly different, even if the size is exactly the same. (Similar to choosing two size large hoodies from different brands – they won’t offer identical fit.)

But I will also say this: Your first bike will likely be completely different compared to the bike you will ride a few years into your BMX journey.

In my case, I started on a 20.5″, but I now ride a frame with a 21.6″ top tube length. Yes, that’s a massive difference.

Finally, if you need additional support, you know where to find me.

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