BMX bikes come in various sizes to fit riders of different ages, heights, and abilities. Choosing the right size BMX bike is essential for safety, performance, and comfort.
This complete guide will help you understand BMX bike sizes and select the perfect size BMX for you or your child.
What Size BMX Do I Need?
Choosing the proper BMX bike size depends on your height, age, riding style, and preference. Here are some general guidelines for selecting the right size BMX:
BMX Size Chart by Age
- Ages 4-7 – 14-16 inch wheel, 12-14 inch frame
- Ages 7-10 – 16-20 inch wheel, 14-16 inch frame
- Ages 10-13 – 20 inch wheel, 16-18 inch frame
- Teens/Adults – 20-24 inch wheel, 18-21 inch frame
BMX Size by Height
- Under 4′ – 16-18 inch frame
- 4′ – 4’6″ – 18 inch frame
- 4’6″ – 5′ – 18-20 inch frame
- 5′ – 5’6″ – 20-21 inch frame
- Over 5’6″ – 21+ inch frame
BMX Size by Riding Style
- Racing – Compact, lighter frames for faster acceleration
- Freestyle – Shorter frames for better maneuverability
- Vert/Park – Longer frames for stability on ramps
- Street/Dirt Jumping – Mid-length frames for balance of tricks and control
Within each size range, you can fine-tune based on your preference for a more aggressive or upright body position. Consult the BMX Bike sizes chart for each manufacturer to compare.
The Key Elements of BMX Bike Sizes
There are a few key measurements that determine the proper sizing of a BMX bike sizes. Being familiar with these dimensions will help you select the best size.
Wheel Size
BMX wheel sizes range from 14-24 inches. Wheel size affects seat height and bike handling. Larger wheels roll faster while smaller wheels are more nimble.
Choose wheel size based on age/height guidelines.
- 14-16 inch wheels – best for young kids under age 8
- 20-inch wheel – standard for most older kids and adults
- 24-inch wheel – extra large for very tall adult riders
BMX Frame Size Chart
The frame size refers to the length of the bike from the seat post to the front of the top tube. Standard BMX frame sizes are 12-24 inches. An appropriately sized frame will allow proper leg extension and bike control.
Top Tube Length
The top tube connects the seat to the handlebars. Its length affects the riding position and reach. Shorter top tubes create a more upright stance while longer top tubes stretch out the body more. Top tube length ranges from 20-24 inches on most BMX bikes.
Standover Height
This is the height of the top tube above the ground. There should be 2-3 inches of clearance between your crotch and the frame when straddling the bike. This ensures you can comfortably mount, dismount, and handle the bike.
BMX Bike Size Charts
Most BMX manufacturers provide detailed size charts to help you select the proper bike size based on age, height, inseam, and riding style.
Here are links to some popular BMX bike brands’ sizing guides:
- Redline BMX Size Chart
- GT BMX Size Guide
- Mongoose BMX Bike Sizing
- Hoffman BMX Size Chart
- Haro BMX Size Calculator
These charts provide recommended frame sizes, wheel sizes, and other dimensions to consider for each height range. Refer to these BMX bike sizes calculators to zero in on the perfect size bike before purchasing.
How to Size a BMX Bike
If you don’t have access to a size chart for a particular brand, you can size a BMX bike by measuring key fit dimensions. Here is a 5-step guide to sizing a BMX properly:
- Measure your inseam – Stand barefoot and measure from crotch to floor. Compare to bike seat height range.
- Calculate standover height – Subtract 2-3 inches from the inseam for proper standover clearance.
- Determine frame size – Use your age and height to select an appropriate frame size (ex: 20-21 inch frame for adult riders 5′-5’6″).
- Gauge top tube length – Choose a shorter or longer top tube based on your body type and riding position preference.
- Assess wheel size – Larger riders may opt for 22-24″ wheels. Standard wheel size for most adult BMX bikes is 20″.
Following these steps will give you a good idea of what size BMX to choose before you test-ride the bike.
BMX Bike Fit
The best way to finalize BMX bike sizing is to actually sit on and test-ride the bike. When assessing fit, consider these factors:
Standover Height
There should be 2-3″ of clearance between your crotch and the top tube when straddling the bike. This allows comfortable mounting/dismounting.
Arm and Torso Length
With the seat at the proper height, you should have a slight bend in your elbows when grasping the handlebars. Avoid over-reaching.
Seat Height
With feet on the pedals, your leg should be nearly straight at the bottom of the pedal stroke. Adjust the seat for comfort.
Handlebar Height
Handlebars should be 1-2 inches below the height of your seat. Adjust stem height to achieve proper position.
Comfort
Make small tweaks to find a fit that feels natural and allows free movement while riding. Don’t compromise comfort.
Choosing the Right Size BMX Matters
Finding the right size BMX bike has a big impact on your riding experience. Here are some key benefits of proper BMX sizing:
Safety
A bike that is too large or small can cause loss of control and increase your risk of crashes and injuries.
Efficiency
The right fit allows optimal pedaling power and handling for faster acceleration, tricks, and jumps.
Comfort
You’ll avoid soreness and pain with a BMX sized to match your body measurements and flexibility.
Technique
Good bike fit gives you proper body positioning for ideal maneuverability, balance, and stunts.
Adjustability
It’s easier to customize a bike that already has the appropriate frame size and wheel size as a starting point.
Don’t compromise on size – take the time to consult sizing charts and test ride bikes to get an excellent BMX fit. Your riding progress and enjoyment will benefit.
Frequently Asked Questions on BMX Sizing
Q1: What size BMX bike do I need if I’m 5’10”?
A: At 5’10”, you would generally need a 21-inch BMX frame size with 20-inch wheels. Always test-ride bikes to choose your ideal reach and handlebar height.
Q2: What’s the best size BMX for adults?
A: Most adult BMX bike sizes are 20-21 inches for the frame size with 20-inch wheels. Taller adults may opt for 22-24-inch frames and slightly larger wheels.
Q3: What size BMX should I get for my 8-year-old?
A: An 8-year-old would typically ride a 16-18 inch frame with 16-20 inch wheels, depending on their exact height and development. Prioritize standover height and comfort.
Q4: Is wheel or frame size more important for BMX fit?
A: Frame size determines minimum standover height and reach. But wheel size also significantly impacts seat height, handling, and acceleration. Both dimensions are critical for proper BMX sizing.
Q5: What size bike do BMX pros ride?
A: Pro BMX riders often opt for shorter top tubes around 20.5-21 inches. This allows greater strength and control for aerial tricks. But amateur riders may prioritize comfort over max maneuverability.
Finding the Perfect Fit
Determining your ideal BMX bike sizes involves research, measurement, and test rides. But taking the time to get the sizing right pays off with a bike that is comfortable, capable, and tailored specifically to your body and riding needs.
Use this guide and don’t be afraid to ask manufacturers and bike shops plenty of questions. Before you know it, you’ll be sailing through the skatepark or dirt trails on a BMX that fits like a glove.