BMX equipment has its own shorthand, and knowing the terms makes it easier to choose parts, follow a setup discussion, or understand what a rider is changing. A “freecoaster,” “top tube,” and “gyro” all refer to different parts or systems—and the right choices depend on whether you ride BMX racing, park, street, dirt, or flatland.
Here’s a practical guide to common BMX equipment terms, what each part does, and where you’re most likely to encounter it. Some parts are shared across BMX disciplines, while others are mainly used for racing or freestyle.
Core BMX bike parts
Frame and geometry
The frame is the bike’s main structure. Its size and shape affect how the bike fits and responds. Riders often compare frames by top tube length, the distance between the head tube and seat tube along the upper part of the frame. A longer top tube can feel roomier; a shorter one may feel easier to move around. Neither is automatically better—fit and riding style matter.
The chainstays run from the bottom bracket area to the rear axle. Shorter chainstays can make a bike feel quick to lift and turn, while longer ones can feel steadier. The head tube holds the headset and fork, and the dropouts are the slots or mounts where the rear wheel attaches.
Fork, bars, and stem
The fork holds the front wheel and steers with the handlebars. Bars are the handlebars; riders may talk about their height, width, or sweep because those dimensions change the feel of the bike.
The stem clamps the bars and connects them to the fork’s steerer tube. A top-load stem holds the bars above the stem body, while a front-load stem holds them in front. These terms describe the clamp layout, not the quality of the part.
Headset and bottom bracket
The headset is the set of bearings and parts that lets the fork and bars turn smoothly inside the frame. The bottom bracket (often shortened to BB) holds the crank axle in the frame. BMX bikes use different BB types, so check that a replacement matches your frame.
Drivetrain terms
Cranks, sprocket, and chain
Cranks are the arms attached to the bottom bracket axle; the pedals screw into them. The front toothed wheel that drives the chain is the sprocket, also called a chainring. The chain carries that motion to the rear wheel.
BMX bikes commonly use a micro-drive setup, with a small sprocket and small rear cog. This can leave more room between the sprocket and the ground or obstacles. The exact gearing affects how hard it feels to start pedaling and how much distance you cover with each pedal stroke. Race riders often choose gearing to suit the track and their acceleration, while freestyle riders may favor a compact setup that is less exposed.
Freecoaster and cassette hub
The rear hub holds the rear wheel and transfers pedaling force to it. A cassette hub engages when you pedal forward and usually makes a clicking sound as you coast. A freecoaster lets the rear wheel roll backward without forcing the pedals to spin backward. That can help with fakie riding, when you roll backward after a trick or turnaround. Freecoasters may need a little forward pedal movement before they engage again.
Wheels, tires, and contact points
A BMX wheel is built from a hub, spokes, and rim. The hub turns around its axle, spokes connect it to the rim, and the rim supports the tire. Wheel size is commonly 20 inches for standard BMX, though smaller and larger options exist for different rider sizes and types of riding.
Tire pressure is usually measured in PSI. Higher pressure can make tires feel firm and fast on smooth surfaces; lower pressure may add grip and comfort, but too little can increase the chance of a pinch flat or damaged rim. Check the tire’s pressure range and adjust for your riding surface and preference.
Grips cover the ends of the handlebars, and pedals provide the surface for your feet. Freestyle riders often use flat pedals, which let them reposition their feet more easily. BMX racers may use clipless pedals, which lock compatible cycling shoes to the pedals for a secure connection. “Clipless” is a confusing name: the system does use a cleat to attach the shoe.
Freestyle-specific equipment
Pegs and hub guards
Pegs are short metal or plastic-covered tubes fitted to the wheel axles. Street and park riders use them for grinds and stalls on rails, ledges, or coping. Some riders run pegs on one side, while others use two or four, depending on their tricks and local spots.
Hub guards cover parts of the hub and spokes to help prevent damage during grinds. They are often made from plastic or metal. Before buying, check that the guard fits your hub and works with the peg and axle setup you use.
Brakes and gyro
A U-brake is a compact rim brake used on many freestyle BMX bikes. The brake pads press against the rim to slow the bike. Some riders remove brakes for certain styles of riding, but brakes are useful for control and may be required at parks or other riding areas.
A gyro, also called a rotor, lets the handlebars spin without twisting the rear brake cable. It is useful for riders who do bar spins while keeping a rear brake. Not every BMX bike has one, and a gyro setup needs compatible parts and correct cable adjustment.
Race equipment and protective gear
BMX race bikes are built for quick starts and repeated laps around a purpose-built track. A number plate attaches to the bars or frame and displays the rider’s race number. Race riders may also use clipless pedals, while younger or newer riders often start with flat pedals as they learn to control the bike.
A properly fitted helmet is essential. BMX racing typically uses a full-face helmet, while freestyle riders may choose a full-face or an approved skate-style helmet, depending on the park’s rules and the riding they do. Gloves, knee pads, elbow pads, and shin guards can add protection. Always follow the requirements of your track, park, event, or local riding area.
| Term | What it means | Most common use |
|---|---|---|
| Top tube | Upper frame tube; its length is a common frame-size measure | All BMX disciplines |
| Freecoaster | Rear hub that allows backward rolling without backward pedal rotation | Freestyle |
| Peg | Axle-mounted tube used for grinds and stalls | Street and park |
| Gyro | Brake cable system that allows the bars to spin | Freestyle with a rear brake |
| Number plate | Plate displaying the rider’s race number | BMX racing |
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Frequently Asked Questions
What is the difference between a freecoaster and a cassette?
A cassette hub engages as soon as you pedal forward and typically clicks while coasting. A freecoaster lets the wheel roll backward without turning the pedals, which is useful for fakies. The feel and maintenance needs differ, so try both if you can.
Do all BMX bikes have pegs?
No. Pegs are common on some street and park bikes, but many riders do not use them. They add weight and can catch on obstacles, so choose them for the tricks you plan to ride rather than assuming every freestyle bike needs them.
What does BMX bike size refer to?
It can refer to the wheel size or frame fit. Standard BMX bikes usually have 20-inch wheels, but frame size is often compared by top tube length. For a comfortable fit, consider your height, reach, and riding style—not wheel size alone.
Is a gyro necessary if I want to do bar spins?
No. A gyro is only needed if you want to keep a rear brake while spinning the bars freely. Some riders use a longer brake cable or ride without a rear brake, but brake rules and safe setup depend on where you ride.
Final Thoughts
Understanding BMX equipment terms helps you talk about bike fit, repairs, and upgrades with more confidence. Start with the parts that affect comfort and control—such as frame fit, bars, tires, and brakes—then look at specialized gear like pegs, hub guards, or a freecoaster if your riding calls for it. Before changing parts, check compatibility and make sure everything is fitted securely.
Aiden Cross is a sports writer and editor at BeliveSports, covering a broad range of sports with a focus on clear, accurate, and practical information. His work covers rules, techniques, player roles, competitions, equipment, statistics, and the details that help readers better understand how different sports are played. Aiden takes a research-driven approach to sports writing, using reliable sources and established sporting information to provide context rather than simply repeating surface-level facts. His goal is to make complex topics accessible while maintaining the accuracy and depth expected by knowledgeable sports fans. At BeliveSports, Aiden contributes to the site’s editorial standards by focusing on accuracy, clarity, useful context, and reader-first explanations.