What Size BMX Bike Do I Need?

Understanding which bike suits you might not have occurred to you, but like the perfect pair of 501 jeans, the geometry of BMX bikes is based on the weight, size, age, and most importantly, the rider’s height.

There has been a growth in the popularity of smaller bikes in recent years, with several companies getting into the balance bike market. For those riders who are too tall for the BMX, there are also options available, with 22″ and 24″ BMX bikes becoming more popular. Choosing the correct size bike will greatly impact how the bike performs tricks and feels when you’re cruising.

Bike frames are made to fit all riding heights, and different geometries will consequently have varying effects. A smaller bike will be less stable for a taller rider, while a bike too big will be almost impossible to ride and lift for a smaller rider.

In this article, we will discuss a few things to look for when selecting the right bike size for you and the benefits of riding the right-sized bike to make every ride awesome.

What Size BMX Bike Do I Need?

The freestyle BMX bikes are designed to handle any stresses caused by stunt riding in streets, skate parks, or dirt jumps and will generally have heavier frames and tires for maneuverability. The race ones are built with lighter frames for extra speed and stability.

BMX bikes come in various shapes and sizes based on age, size, weight, and rider’s height. With this guide, finding the right bike for your needs will be as simple as visiting a few bike shops or online stores.

How To Measure Bike Frame Size

When it comes to size, there are three factors to consider:

  • The rider’s height
  • The rider’s weight
  • The Rider’s Comfort

Even though rider height and weight are important factors to consider when choosing the right size BMX bike, comfort will tip the scales. Depending on the rider, a slightly larger or smaller bike might be better.

It is a good idea to visit BMX tracks to get a feel for what size bike you need. Most tracks provide loaner bikes and helmets. Try different bikes to find the one that fits the best.

However, this basic chart is an excellent guide.

Rider HeightRider WeightFrame SizeTop Tube Length
4.0″ and under40 to 65 lbsMicro-Mini15″ to 16″
4.0″ to 4.6″50 to 85 lbsMini16″ to 17.5″
4.4″ to 4.10″60 to 100 lbsJunior17.5″ to 18.5″
4.8″ to 5.4″70 to 110 lbsExpert18.5″ to 20″
5.2″ to 5.8″75 to 125 lbsExpert XL19″ to 20″
5.6″ to 5.10″100lbs and overPro20″ to 20.5″
5.10″ to 6.0″140 lbsPro XL20.5″ to 21″
6.0″ and  over160 lbsPro XXL21″ to 22″

 

The Right Size Bmx Matters

It is important to choose a BMX bike with precisely the right top tube length to achieve comfortable riding with ease of maneuvering. Since top tube lengths vary between manufacturers, you are looking for one with the perfect top tube length to achieve effortless maneuverability.

Many BMX bikes are available in wheel sizes from 12 inches to 24 inches, with 20 inches being the most popular with varying top tube lengths. When choosing the right BMX bike size, the top tube length is the most important factor.

The top tube of a bike with a shorter top tube can be beneficial in some cases for taller riders to make quick moves and achieve a good low-speed balance. However, shorter riders typically prefer longer bikes because they are more stable at high speeds and capable of jumping raised trails.

What To Consider In BMX Bike Parts

Here are what to look for in BMX bike parts.

Wheels

BMX Bike wheels

BMX wheels typically measure 20 inches, which is smaller than mountain bike or road bike wheels. A kid’s bike might have a wheel diameter of 16″ or 18″, whereas a BMX bike with a bigger wheel diameter of 22″ or 24″ is used for dirt jumping. Additionally, a 20-inch wheel bike is ideal for racing.

It is possible to find racing BMX bikes in two sizes, depending on wheel diameter. The first one is the most common at 20-inch wheels, while the second is called a cruiser. Taller or older riders tend to favor cruiser bikes because they provide more stability.

Since track racing BMX requires lightning-fast acceleration, the wheels are lighter than those used in freestyle BMX.

Rims

BMX Bike Rims

Typically, the rim is made from aluminum and can be either single, twin, or triple walled. The multiple layers of metal will provide more structural support but will increase weight. For most riders, the double-wall is a good balance of strength and weight.

The more experienced riders with higher demands on their bikes often have their wheels built up aftermarket to fit their needs specifically and be pickier about spokes and rims. To suit their particular needs, advanced bikers prefer aftermarket-built wheels.

Tires

BMX Bike Tires

In BMX riding, tires are crucial in controlling speed, grip, and overall performance. Wider and smoother tires are perfect for street riding and park riding.

A tire with more tread is best for dirt jumping because it offers better traction and grip even at low pressure. Racing tires have narrow rims and are lighter, which allows them to run at fast speeds.

For BMX riding, a mix of pavement and dirt-bound tires is critical. The terrain is hard-packed dirt, so having low rolling resistance is essential. A tire’s tread should possess maximum speed, traction, and grip to facilitate propelling and turning.

It’s important to check the maximum pressure of your tires. Premium tires are inflated to higher pressures, reducing rolling resistance, which allows faster speeds.

Handlebars

BMX Bike Handlebars

Most BMX racing bikes use aluminum or carbon handlebars to reduce weight and maintain strength. Aluminum or carbon bars are typically used on BMX racing bikes.

When selecting handlebars, keep the following in mind:

The maximum width generally permitted is 30 inches. Check your league’s rules for this information.

Riders should not exceed the maximum weight restrictions of lightweight handlebars. Make sure they stay within these limits for the sake of safety.

Chains And Sprockets

BMX Bike Chains And Sprockets

If your gear size is large than 58, you will accelerate faster, but takeoff will be slower.

With a high gear, top speed will take longer. It will be difficult to snap out of the gate, go uphill, take turns quickly, etc. On the other hand, a low gear size of 55 or less will provide a better start but a low speed.

Frame Size

 

Even though freestyle bikes are designed mostly for kids, teenagers, and adults who like stunts on the streets, their frames can differ subtly to suit riders of different heights and riding styles. The most important factor for picking the right BMX bike fit is a comfort since different riders may prefer larger or smaller bikes.

Brakes

Bike Brakes

BMX bike brakes must be of high quality with pure stopping power to offer better modulation and prevent accidents. The brakes on most BMX bikes tap against the rims to slow the bike down. Many freestyle bikes feature U-brakes in the front and back. They are often equipped with a “gyro” brake system or a detangler to allow a 360-degree spin without being tangled. Front brakes are not necessary for BMX racers; they prefer reliable linear-pull rear brakes.

Spokes

When choosing BMX bike fit, another factor to consider is the number of spokes. The number of spokes determines the wheel’s strength and weight.

The spokes are connected by lace from hub to rim and are tension-dependent for optimal functioning and strength. BMX bikes with 36 spokes work well for freestyle riding, while BMX bikes with 48 spokes are more suitable for advanced or heavy riders. BMX bikes with race wheels usually have 28-36 spokes.

Hubs

BMX Bike Hubs

BMX bike wheels are made up of small alloy hubs that contain the bearings that spin the wheel.

Seal-free bearings are used in most suitable bikes, making the ride smooth and reliable. The choice of axle size varies, with BMX bikes using 14mm axles and flatland bikes using 10mm axles for weight savings.

Gearing

There are not many gears in BMX bikes, so the most important consideration is the gear ratio, which is the number of teeth on the chainring to the number on the sprocket. BMX gear ratios typically range from 25:9.

A smaller gear ratio is preferred on flatland and street BMX bikes to perform complex tricks with greater ease. In BMX racing, riders need to generate more power, so a bigger chainring is needed, but it can vary depending on the race track.

Cranks

BMX Bike Cranks

Cranks attach pedals to the rear sprocket of a BMX bike. They come in a variety of materials, sizes, and styles. The strongest and most durable cranks are made of Chromoly.

In freestyle BMX, short cranks are preferred for better clearance while performing stunts on the streets. BMX race cranks are constructed of lightweight aluminum, and the rider’s height determines their lengths.

What To Consider When Choosing A BMX Bike

The process of choosing a BMX bike can appear complicated at first. There are tons of options and designs available so that you might feel lost in a sea of bikes without guidance. However, you will get a lot of help from this guide.

Sizing

It’s crucial to find the right bike size; otherwise, you could suffer discomfort and possible injury. For instance, you need to find the right top tube length. The top tube length helps ensure you have enough leg room between the seat and the handlebars. It is based on height, so you will need a longer top tube if you are taller. If you can try out bikes in the parking lot, make sure the bikes are comfortable.

Know Your Budget

It’s important to know your budget. If you cannot afford a $1,200 bike, it is not worth your time to fall in love with it. There are lots of excellent bikes in a wide range of price ranges. From starter bikes to custom builds, you’ll always be able to find something within your budget.

You should not sell yourself short and settle for an inferior ride to save a few bucks. Know your budget and maximize it. Hopefully, these tips help you accomplish just that!

Beware Of Your Skill-level

If you haven’t ridden for a while, it’s okay; we all started somewhere. But, if you’ve been riding for a while, you’re likely to want something with more features.

Know Your Style

Different riding styles exist in BMX, and each has a unique look, frame geometry, and parts to support that specific aspect of the sport. You should know what type of riding you want to do before you look for bikes. While some bikes can be used interchangeably, others are intended specifically for a particular riding style.

Materials

There is a wide variety of materials used to make BMX bikes, each with its own pros and cons. As a result, better quality material is more expensive and vice versa. Aluminum material is ideal if you want something extremely lightweight as a racer. Though it is less durable than steel or Chromoly, it will certainly make you fly.

Brand Parts

If you are looking for BMX bike parts, it’s crucial to look for brand name parts from companies like Framed, The Shadow Conspiracy, ODI, Odyssey, and others, since they tend to be durable and lighter than generic options.

When looking for a new BMX bike, smaller parts are better. Using smaller parts means less metal, so there are fewer things to get in your way while you ride, and the weight is decreased. You should start by upgrading your sprocket from a 45-to-25 or 28-to-28 toothed sprocket.

Sealed Bearings vs. Unsealed

Sealed bearings protect against moisture penetration and degradation, while unsealed bearings become damaged by weather and require more maintenance. Having sealed bearings in wheels, bottom brackets, and headsets will keep your bike moving all year smoothly.

Conclusion

There are a lot of different BMX bikes available on the market. You must choose the right size to suit your height and the type of trails you will be riding on. Additionally, you should test-ride the bike before purchasing as some look right but might not feel right after riding.

If you plan to ride on trails, most complete BMX bikes have a 20″ frame size or wheel size and can function in almost any situation. It’s up to you to determine the right fit. Good luck!