How to Find the Right BMX Bike Size: BMX Bike Size Chart & Guide

How to Know What Size BMX Bike You Need

Do you ever want to buy a BMX bike but you don’t know the right size for your needs? We’ve got the guide just for you – we want to help you choose a properly-fitting BMX for your enjoyment, comfort, and safety when riding.

Here’s what you need to know when you want to find the right BMX size:

Wheel size

The most common wheel sizes in BMX bikes range from 12 to 24 inches. Since BMX is more of a trick bike rather than for riding longer distances, the wheels are expected to be not so big as compared to a cruiser or MTB wheels.

If you can’t decide on what wheels you need, you can just go for the most common size, which is a 20-inch wheel. With that said, even a 20-inch BMX will have a variety of top tube (TT) sizes, which we will mention below.

Top tube

The top tube measurement, also known as TT, is what you’ll need to find out on a BMX bike before buying. Compared to frame size, which is measured from the seat post to the pedal joint, TT is measured from the seat post to the bottom handle of the bike.

Measuring the top tube is very crucial when it comes to BMX bikes. Even if you have a bunch of 20-inch bikes, they might vary when it comes to top tube measurement. We will give you a size chart below to give you more ideas on how to find the right BMX bike size for your needs.

Rider height

Of course, when choosing your BMX bike, you have to know your height as well. In some cases, this might also translate as “discipline” or the rider class you belong to. We’ll also mention below the different BMX classes, which also dictate the suitable BMX bike for your needs.

What are the classes in BMX?

BMX classes dictate where a rider belongs when it comes to racing competitions. The four factors that decide this are age, wheel size, gender, and the level of proficiency of the person who will ride the BMX bike. Let’s have a look at some of them:

Gender and Age Classes

Boys and girls have their separate classes depending on their age. They are never together in a single class and are also grouped by other factors. The only time when girls are allowed in a boy’s class is when there aren’t enough girls on a racing day.

Here’s a rough idea of the different gender and age classes: they can be grouped to wheel size (mentioned below) and each of them has its age bracket, as well as classes (novice, intermediate, expert, cruisers, girls, and girl cruiser).

To find out more, you can check out this official listing of the USA BMX so that you’ll know the complete list of classes per age and other factors.

Proficiency Classes

Proficiency pertains to the skill level of the rider, which is typically Novice, Intermediate, and Expert. Novice stands for beginners (both genders), Intermediate for boys who win at least 10 BMX races, and Expert for at least 20 wins boys.

For girls, however, there is also a separate class from the boys. There is a Girl class specifically for female riders and this is also the highest proficiency level of the said gender.

Wheel Size Classes

Usually, there are two groupings when it comes to wheel size: 20-inch and 24-inch BMX bikes. The 20-inch bike, sometimes known as the class bike, is suitable for most beginners and intermediate riders. The cruiser size, however, is designed for tougher races.

Race BMX bike size chart

Freestyle and racing are two categories of BMX – both of them have specific needs when it comes to bike sizing and features. If you want to know which BMX bike size suits your next racing needs, we have a chart below:

Rider height	Below 3’	3’ to 4’	4’ to 5’	5’ to 6’	6’ and above
Recommended wheel size	12 inches	Micro mini	Mini, Junior, or Expert	Expert, Pro, or Pro XL	Pro XXL

The reason why there’s no ideal top tube size here is that it depends on your class size. Feel free to pick a TT size that’s suited to your racing class.

Freestyle BMX bike size chart

If you are more of a freestyle BMX rider than a racer, here’s a size chart for choosing the right bike for your needs:

Rider height	Below 3’	3’ to 4’	4’ to 5’	5’ to 6’	6’ and above
Recommended wheel size	12 inches	12 to 16 inches	16 to 20 inches	20 inches	20 inches and above
Ideal top tube size or length	Depending on your comfort and confidence levels	Depending on your comfort and confidence levels	Small top tube up to 20 inches	20 ½ to 21 ½ inches	21 to 22 inches

BMX bike size chart by height

For those who want a specific BMX bike chart depending on the rider height, here’s a guide just for you. We listed the height in both metric and imperial systems for your convenience:

Rider height	3’7”	4’	4’10”	6’4”
Recommended wheel size	16 inches	18 inches	20 inches	20 inches and above
Top tube size	Depends on comfort and confidence	Up to 20 inches	20 ½ to 21 ½ inches	21 to 22 inches

BMX bike size chart by age

If you want to find out the ideal bike size that you need depending on your age, here’s a chart for you as well:

Rider age	5 years old	7 years old	11 years old	Above 11 years old
Recommended wheel size	16 inches	18 inches	20 inches	20 inches and above
Top tube size	Depends on comfort and confidence	Up to 20 inches	20 ½ to 21 ½ inches	21 to 22 inches

BMX bike tire size chart

Choosing the right tire for your BMX bike will depend on the riding class and the age of the rider. Here are some of the most common classes and the ideal tire sizes:

Rider class	Mini	Junior	Expert	Pro
Typical age (years)	4 – 6	6 – 9	9 – 13	13 and above
Ideal tire size	20 x 1 1/8”	20 x 1 3/8”	20 x ½ to 1 ¾”	20 x 1 ¾ to 2.2”

BMX bike wheel size chart

The ideal bike wheel you should get depends on your class and height, such as with the following:

Wheel size	12 inches	16 inches	20 inches
Ideal user height	3′ to 4′	4′ to 5′	5′ and above

How to measure BMX bike size

BMX bikes are typically measured using the following:

• User height, which also defines your racing class
• Wheel size, typically from 12 to 20 inches
• Top tube length, ranging from 19 to 22 inches
• Other BMX bike parts such as stem length, crank arm, and bar position

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