Bmx bikes are a type of bike that was originally designed for BMX racing. These bikes typically have a shorter frame and smaller wheels, making them perfect for street use as well as BMX tracks. The size of your BMX bike will depend on the weight and age of the rider, so it is important to consult with an expert before purchasing. Here is the BMX bike size chart:
|Rider Height||Frame Size||Toptube Length||Stem Length|
|4’4″ & under||Micro||15″ – 16.5″||Mini: 25mm – 35mm|
|4’2″ – 4’10”||Mini||16″ – 17.5″||Mini-Mini XL: 30mm – 40mm|
|4’6″ – 5’1″||Junior||17″ – 18.5″||Mini XL-Expert: 40mm – 45mm|
|5’0″ – 5’4″||Expert||18.5″ – 19.5″||Expert-Pro: 43mm – 48mm|
|5’2″ – 5’6″||Expert XL||19.5″ – 20″||Expert-Pro: 43mm – 48mm|
|5’3″ – 5’8″||Pro||20″ – 20.5″||Pro: 50mm – 55mm|
|5’7″ – 6″||Pro XL||20.5″ – 21.25″||Pro XL: 50mm – 55mm|
|6″ & over||Pro XXL||21.25″ – 22″||Pro XXL: 52mm – 60mm|
The following chart provides an overview of the various dimensions of 20-inch and 24-inch BMX bikes:
20-Inch BMX Bike Dimensions:
- Wheel diameter: 20 inches
- Frame size: 10-12 inches (measured from the center of the bottom bracket to the top tube)
- Crank length: 3.5-4.5 inches
24-Inch BMX Bike Dimensions:
- Wheel diameter: 24 inches
- Frame size: 12-14 inches (measured from the center of the bottom bracket to the top tube)
- Crank length: 4.5-5.5 inches
What is the right BMX bike size for you?
Choosing the right size BMX bike is important. If you get a bike that is too big or too small, it will be very difficult to ride. You need a bike that you can control and that is the right size for your height and weight. The best way to find the right size bike is to use a BMX bike size chart.
Top Tube Length
The top tube length is the distance between the head tube and the seat tube. The head tube is the portion of the frame that houses the fork and handlebars. The seat tube is where the seat post is inserted. The ideal top tube length depends on your riding style and how you want your bike to feel.
If you’re looking for a bike that’s agile and quick, you’ll want a shorter top tube. This will make your bike feel more maneuverable. If you’re looking for a stable ride that’s comfortable for long rides, you’ll want a longer top tube. This will give you a more relaxed riding position.
The right top tube length for you is a personal preference. Use this chart as a starting point, but don’t be afraid to experiment until you find what feels best for you.
Rider Height (in.) Top Tube Length (in.)
- 4’10” – 5’2″ 16″ – 17″
- 5’3″ – 5’6″ 17″ – 18″
- 5’7″ – 5’10” 18″ – 19″
- 5’11” – 6’2″ 19″ – 20″
- 6’3″ and up 20″ and up
Chainstay length is, along with toptube length, one of the two main dimensions that determine a BMX frame size. It’s the distance between the center of the bottom bracket and the rear axle, as shown in this illustration.
A bike’s chainstays have a big impact on how it rides. Shorter chainstays make for a snappier, more agile bike. They also make manuals and other tricks easier since your wheels are closer to the center of the frame. On the other hand, longer chainstays add stability and traction since your weight is more evenly distributed between the front and back wheels.
Most BMX frames have between 13″ and 14.5″ long chainstays. That said, there are some exceptions. For example, certain frames designed for street riding or park riding will have shorter chainstays (around 13″) while those meant for dirt jumping or racing will usually have longer stays (around 14″). There are even a few specialty frames with super short (11-12″) or super long (16-17″) stays, but these are less common.
As a general rule of thumb, smaller riders tend to prefer shorter stays while taller riders tend to prefer longer stays. That said, like top tube length, there is no perfect formula for translating rider height into ideal chainstay length. The best way to know if a bike’s stays are too short or too long for you is to take it for a test ride and see how it feels.
The wheelbase of a BMX bike is the distance between the centers of the 2 wheels.Depending on the type of terrain you will be riding on and the tricks you want to do, you will want to choose a different wheelbase. A shorter wheelbase is better for doing tricks on flat ground and racing, while a longer wheelbase is better for cruising and jumping.
- Racer: 13-15 inches
- Jumper: 15-17 inches
- Flatland: 13-17 inches
One of the main concerns when choosing the right BMX bike size is the standover height. For a street BMX you will want a bit more height, but for a race bike you will want to be able to get low. The standover height is measured from the top tube to the ground. You should have 2-3 inches of space between the top tube and your groin. This will give you enough room to move around on the bike without risking injury.
If you are between sizes, it is better to go with the smaller size. This will give you more control over the bike and make it easier to do tricks. If you are still not sure, take a look at our BMX Buying Guide for more advice on choosing the right BMX bike for you.
How to measure your BMX bike size
To measure your BMX bike size, you will need a tape measure and a friend to help you. With your friend’s help, measure the distance from the ground to your crotch. This is your inseam.
Next, measure the distance from the center of the bottom bracket to the top of the seat tube. This is your seat tube length. Finally, measure the distance from the center of the head tube to the center of the seat tube. This is your top tube length.
Top Tube Length
The best way to determine your proper BMX bike top tube length is to measure the distance from the center of the head tube to the center of the seat post. This measurement is called the “effective top tube length” and will be different than the actual top tube length measurement of your frame.
The seat post length will also factor into this equation, so be sure to take that into account when measuring. If you don’t have a tape measure handy, you can also use a piece of string or even a broom handle to get an approximate measurement. Just be sure to measure in a straight line and not following the contours of your frame.
Chainstay length is the distance between the crank and the rear axle. To determine your ideal chainstay length, measure your inseam and multiply it by 0.665. This number is your ideal chainstay length in inches. Most BMX bikes have a chainstay length between 13 and 16 inches.
The wheelbase of a BMX bike is the distance between the centers of the two wheels. To measure the wheelbase, place the bike upside down on a level surface and measure from the center of the rear axle to the center of the front axle.
To measure your standover height, place the bike upside down and rest the top tube on your hip while straddling the bike. There should be 1 to 2 inches of clearance between you and the top tube. If there’s less clearance, the bike is too small; if there’s more, it’s too big.
There is no perfect BMX bike size. The best BMX bike size for you depends on your height, your skill level, and the kind of riding you want to do. You also need to take into account the type of BMX bike you want. If you are a beginner, a smaller BMX bike will be easier to control. A taller rider or a more experienced rider will need a larger BMX bike.
The best way to find the right BMX bike size for you is to go to a BMX shop and talk to the staff. They will be able to help you choose the right BMX bike for your needs.