What is a BMX Bike? A Complete Guide for Beginners

So you saw some cool videos of people doing wild tricks on small bikes and wondered – what are those? They’re BMX bikes!

BMX bikes are compact, stunt-oriented bicycles built for dirt tracks, skateparks, streets, and trails. With their lightweight, durable construction and responsive handling, BMX bikes allow riders to get airborne and perform all kinds of technical tricks.

In this comprehensive guide, we’ll cover everything a beginner needs to know about BMX bikes:

A Brief History of BMX

BMX stands for Bicycle Motocross. The term was coined when teenagers in California during the 1960s started racing their bikes on dirt tracks modeled after motorcycle motocross courses.

These early BMX pioneers took modified old single-speed bikes with coaster brakes and fabricated their own jumps. It was a DIY movement that quickly gained popularity across the US.

In the 1970s, manufacturers began making the first purpose-built BMX bikes tailored for quick handling and durability. Trail riding and racing advanced the technology, while a new freestyle movement focused on tricks and stunts.

By the 1980s, BMX exploded globally as an organized sport. Today it is recognized as an Olympic event and bicycle motorsport discipline with millions of participants worldwide.

BMX continues to evolve as a dynamic action sport and lifestyle. Next, we’ll explore key types of BMX bikes.

Types of BMX Bikes

While all BMX bikes are small and designed for stunt handling, there are differences between bikes built for various disciplines:

Type	Description
BMX Race Bikes	Made for racing on dirt oval tracks. Very lightweight, rigid frames. Knobby tires, no pegs. Single speed or multiple gears. Powerful linear pull brakes.
Freestyle BMX Bikes	Ridden exclusively on smooth flat ground. Frame geometry optimized for stability. Often no brakes, and zero-offset forks. 24″ or 26″ wheels with wide tires.
Dirt Jumper BMX	For dirt jumping trails and slopes. 24″ wheels with suspension forks. Front and rear hydraulic brakes. Durable wheels and tires.
Flatland BMX	Ridden exclusively on smooth flat ground. Frame geometry optimized for stability. Often no brakes and zero-offset forks. 24″ or 26″ wheels with wide tires.

Now let’s dive deeper into BMX design, parts and sizing.

Key Design Features of BMX Bikes

While there are nuanced differences across riding styles, most BMX bikes share common traits:

• Compact Frames – Small 18″ to 22″ frame sizes. Made of lightweight chromoly or aluminum. Low standover height for maneuverability.
• Integrated Headsets – Bearings press directly into the head tube. Reduces stack height for lower center of gravity.
• Mid Bottom Brackets – Improves grip and stability by lowering the rider’s center of gravity.
• Shorter Wheelbase – Allows tight, responsive steering, ideal for spins and tricks.
• Pegs – Metal pegs that screw into rear dropouts and frames. Enable riders to “grind” on edges and rails.
• Detangler System – Allows handlebars to spin 360 degrees without tangling brake lines.

Next, let’s look at the key components that make up a complete BMX bike.

Main Parts of a BMX Bike

BMX components need to balance durability with low weight. Here are the most important parts:

Part	Description
Frame	Made of chromoly steel or lightweight aluminum. Smaller 18” to 22” sizes for nimble handling. Designed to withstand impact while landing jumps.
Fork	Typically a rigid chromoly fork for strength and stiffness. Some larger 24” bikes feature suspension forks. Axle-to-crown measurements around 390mm.
Handlebars	Made of chromium-molybdenum alloy for optimal strength. Rise of 2”-4”, widths between 28”-30”. Often fitted with crossbars for stunts and barspins.
Stem	Forged aluminum to resist flexing under stress. Front load or top load styles, angled up for bar height. Integrated with headset bearings on race-style bikes.
Grips	Durable BMX-specific grips provide control. Composite or rubber with molded finger grooves. Usually 130-150mm in length.
Wheels	Lightweight 36-48 spoke single wall rims. 20”, 24” or 26” sizes depending on bike type. Fast engaging cassette hubs, 110mm spacing front, 135mm rear.
Tires	Wide, knobby tires with large side lugs. Softer compounds on dirt jump and freestyle bikes. Low-tread slick tires common on flatland and street bikes.
Crankset & Drivetrain	Three-piece chromoly crank arms, 175mm length standard. Mid or Spanish style bottom brackets. 25 tooth to 33 tooth chainring sizes. Cassette or freewheel rear cog sets.
Brakes	Powerful rear u-brakes provide quick stopping. Front brakes on race BMX and dual setups on some freestyle. Gyro brake detangler allows spinning bars without tangling cable.
Pegs	Allow riders to grind and stall on edges. Steel pegs screw into the rear dropout axle holes. Also mounts on the front triangle of some frame designs.

Next, let’s discuss how to find the ideal size BMX for your riding style and body type.

How to Determine the Correct BMX Frame Size

Because BMX bikes are used for stunts and tricks, proper frame sizing is very important for control and safety.

The key measurement is the top tube length, which ranges from 16″ on kids’ bikes to 24″ on pro extra long (XL) race bikes.

Here are general BMX size ranges by rider height:

Rider Height	Top Tube Length
4’0″ – 4’6″	16″ – 18″
4’6″ – 5’0″	18″ – 20″
5’0″ – 5’6″	20″ – 21″
5’6″ – 6’0″	21″ – 21.5″
6’0″ – 6’6″+	21.75″ – 24″

However, these are just guidelines. To find your perfect fit:

• Stand over the top tube with 1-2″ clearance
• Make sure you can comfortably reach and control the bars
• Do a test ride to ensure the bike handles nimbly beneath you

Don’t size a BMX bike like a road or mountain bike. Their compact frames and stunt-oriented geometry require a different approach.

Dialing in the right size will pay dividends for bike control, maneuverability and safety as you progress in the sport.

BMX Weight Limits

Due to their small size and intended use for aerial tricks, BMX bikes have lower weight limits than other bikes:

BMX Type	Weight Limit
Race BMX	175 – 200 lbs.
Freestyle	200 – 220 lbs.
Dirt Jumper	220 – 250 lbs.
Flatland	250 – 275 lbs.

These limits are for complete bikes with average parts. Stronger aftermarket components can increase limits. But lighter riders will have an easier time controlling the bikes as designed.

Exceeding weight limits stresses frames risking damage and dangerous failures. Heavier riders may prefer other bike types or reinforcing frames and parts.

Now let’s go over some key maintenance tips to keep your BMX bike performing well.

BMX Bike Maintenance Tips

BMX bikes endure heavy impacts from stunts, which can loosen parts and strain components. Stay on top of maintenance:

• Inspect the bike thoroughly before every session – Look and feel for any loose, damaged, or worn parts that need tightened, repaired, or replaced. Do a bolt safety check.
• Keep the chain lubricated – Disassemble, clean, and re-lube the chain every few rides to reduce friction and component wear.
• Check tire pressure frequently – Low pressures lead to sluggish handling, rim strikes, and flats. Inflate tires to the recommended PSI printed on the sidewalls.
• Wipe down the frame – Use a wet rag to remove dirt, dust, and grime to prevent finish damage or corrosion.
• Watch spoke tension – Impacts from landings can loosen spokes. Squeeze pairs to feel for tension consistency. Retrue wheels as needed.
• Upgrade components – As your skills progress, consider stronger aftermarket wheels, tires, cranks, and more.

Taking good care of your equipment will maximize fun and progression while reducing injury risk. BMX is very hard on bikes, so be diligent about safety checks and maintenance.

Frequently Asked Questions

What’s the difference between freestyle and jump BMX bikes?

• Freestyle bikes are optimized for the skatepark with 20-21″ top tubes, shorter chainstays, sealed bearings, etc. Jump bikes have slacker head angles, bigger frames, 24-26″ wheels and suspension forks for dirt jumps and trails.

How much does a good beginner BMX bike cost?

• Expect to spend $300 – $600 for a quality starter BMX. Race bikes with better components run $800 – $2000. Custom builds can cost more.

At what age can kids start riding BMX bikes?

• Most manufacturers recommend a minimum age of 4 years old and height over 3’5″. But always check your child has the balance skills and coordination first before progressing to ramps, jumps and tricks.

Do I need special shoes for BMX riding?

• Flat pedal BMX shoes with grippy soles are ideal, but any athletic shoe with a flexible sole will work. Avoid shoelaces that could get caught in the drivetrain. Cycling specific shoes that clip into pedals are not used.

So there you have it – a comprehensive overview of the different types of BMX bikes, key components, sizing considerations, and general maintenance practices. Understanding the bike’s intended use and properly fitting yourself is key. Then you’ll be ready to start learning tricks and progressing safely in this exciting action sport. Any other questions? Just let us know!