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How to Choose and Buy the Best BMX Bike
What is BMX ?
|A 1957 FX race in the St. Anthonis region|
BMX stands for ‘Bicycle Motocross’. Before the name BMX existed, kids and teenagers used bikes to emulate their heroes in the world of off-road motorbike racing (motocross). This was happening across the United States and Europe.
In mid-’50s Holland, riders from several villages were involved in Fietscross (FX for short or ‘bicycle-cross’ in English).
The first recorded organized race took place on ‘Queensday’, April 30, 1956 in St. Anthonis. This race took place on dirt with berms and prototypical ‘pie plates’ that displayed racer numbers.
|Proto-BMX USA: A modified cruiser||Ron Mackler organized America’s earliest races|
While BMX historians point to the Queensday race as the origin of modern BMX, the first events to lead to regularly organized races took place in the United States.
|This magazine commemorates a 1956 FX race|
Dutch riders initially used widely available adult bicycles. These used large 26” and 28” wheels. FXers would move on to ladies’ bicycles, due to the agility of their smaller frames and wheels. These bikes would be modified by attaching an additional crossbar to their step-through frames.
Over 5000 miles away and roughly a decade later, riders in the United States were modifying cruiser bikes for off-road use. Knobby tires were added, sissy seats were removed and frames were modified with gussets, for strength.
The first known organized BMX race in the United States was held at Palms Park in Santa Monica, California and hosted by Ron Mackler on June 10th, 1969. In 1970 the B.U.M.S. (Bicycle United Motocross Society) track was established in Long Beach, California by Scot Breithaupt.
In 1973, the NBA (National Bicycle Association) was formed. This became the governing body for BMX, giving rise to the first nationals in 1974. After this, the sport blew up and grew exponentially throughout the 1980s and 90s.
|Motocross star Bob Hannah jumps Rick Burgett||A young rider copies his motocross heroes|
What Makes a BMX a BMX ?
|From the smallest…|
BMX bikes are ridden by everyone from small children to adults, but the standard wheel size stays the same. So why the tiny 20” wheels? Why the compact frame?
As the history of BMX shows, the first bikes were modified by kids who emulated their motocross heroes. As the sport evolved, it was found that the small wheels and frame helped to keep these bikes maneuverable and relatively light, while remaining tough.
|…to the tallest.|
BMX races are short, so smaller wheels easily cover the required distances while remaining incredibly robust in the face of massive impacts. In official racing there is also a ‘Cruiser Class’, which uses 24” wheels. But ‘unofficially’, BMX bikes are made with wheels from 12” all the way up to 29”, so everyone can get involved.
A small frame aids agility. It’s easy to launch, easy to throw around and doesn’t get in the way when performing tricks.
|This freestyle BMX has its seat ‘slammed’|
Another notable characteristic of the BMX is its low seat height. BMX riders rarely use a seat for long periods of time.
Races are short, requiring riders to stand on their pedals or to be in the air most of the time.
For freestyle and street riders, a low seat height ensures that vital body parts are protected from damage when landing jumps and performing stunts. It also enables the rider to grip the seat with their legs or thighs when performing no-handed tricks.
Unlike mountain bikes, modern BMX bikes never use suspension.
Riders need rigidity and stiffness for maximum thrust and power, to flow through tracks on jumps and whoops.
On a dirt jump track or BMX park, suspension would sap considerable momentum.
BMX bike frames are built from steel, aluminum and sometimes carbon fiber tubing. Let’s take a look at the when, where, how and why of each of these options.
|A lightweight 7005 aluminum race frame||A lightweight chromoly steel race frame|
|Tough full-chromoly freestyle rig|
Steel was the original BMX material. It remains the most popular choice for freestyle bikes and any BMX used and abused off the race track. As is the case with all bicycle frames, there are two distinct steel types.
Chromoly steel is the most desirable option on a bike designed to take big hits, due to its pliability and compliance. It also possesses the ability to be drawn into tubing that is relatively light and thin without compromising strength. Chromoly tubes often feature reinforcement at their ends and joins.
tough and light dirt jumper
Because of these advantages, chromoly bikes are the most-used bikes for street and freestyle riders. Lighter builds enable superior acceleration and performance. Chromoly bikes have a high stress rating, resulting in improved durability, along with the ability to withstand severe impacts and abuse.
For freestyle riders, the extra weight (compared to aluminum) is not a concern. Chromoly tubing is also used on beginner race bikes. When it comes to pro racing, weight is a priority, hence the preference for aluminum or even carbon fiber.
|This bike’s top-tube and down-tube is hi-tensile steel. The rest is chromoly|
Some manufacturers will list a frame as being made of chromoly steel, while only one or two chromoly tubes are used (usually in the shortest tube which is the seat tube). The rest is hi-tensile steel. Just be wary of this situation. It isn’t a problem as long as you know what you’re paying for.
Compared to hi-tensile tubing, chromoly frames are resistant to fatigue while being easy and affordable to repair. This is not the case with aluminum, which is also more costly than most chromoly options.
|This 100% Hi-Tensile bike is a
sound beginners’ option
Hi-tensile tubing is used to build lower-cost frames for beginner BMXers and kids. It’s heavier and more rigid than chromoly steel.
Hi-tensile frames can be ridden hard to perform tricks at a ‘pro level’, but sooner or later they will break. Damage will occur earlier than on a chromoly frame and won’t be economical to repair.
For kids, casual riders and beginners on a budget, a hi-tensile steel frame can definitely be the right choice.
|An alloy-framed 24″ race bike|
A lot of race bikes are made of aluminum, due to this metal’s light weight and stiffness. These bikes are strong and more than capable of bearing the stresses of landing track jumps.
Nevertheless, aluminum does have a lower stress rating than chromoly steel. This makes it less suited to freestyle and street riding, where big hits are frequent and could lead to the cracking of an aluminum frame.
A number of aluminum race bikes use a chromoly or carbon fiber fork to reduce vibration and better absorb impact on landing.
|Alloy frame with a chromoly fork||Alloy frame with a carbon fork|
Lower quality aluminum frames may be similar in weight to some steel bikes.
|A full-carbon race bike|
Carbon fiber is relatively rare in the BMX world, but it is used to build some high-end race bikes.
It’s light, strong and doesn’t rust. It’s also quite expensive.
Some riders fear that carbon fiber has the potential to snap
Given the new construction techniques used on quality builds, snapping is unlikely.
Carbon fiber is very stiff and potentially less responsive and compliant than chromoly steel. For this reason, it suits racing but not freestyle riding.
BMX Riding Styles
|A solid beginner’s everyday rig|
There are distinct ‘schools’ of BMX riding that require a certain type of bike.
For small kids and beginners that aren’t into competitive racing, an all-rounder type bike can cover day-to-day riding.
For dedicated racing or to land serious tricks, it’s wise to buy a purpose-built bike.
Here are the main BMX disciplines and the bikes used to ride them:
|Young racers jumping on their micro bikes|
BMX racing is sometimes known as ‘true BMX’. It is the original form of BMX competition.
In its earliest days, BMX racing was heavily influenced by motocross competition.
Races take place on short purpose-built tracks of 900 to 1300 feet in length.
These tracks feature a series of jumps, berms, ‘doubles’ and ‘triples’.
|Adult racers round a berm|
Doubles and triples can be jumped or ridden over in ‘pump track style’.
Race bikes are lightweight, often being made of aluminum. They use a single rear brake and do not have pegs or accessories.
Depending on rider age and height, race bikes are available in a range of size categories known as Micro, Mini, Junior, Expert and Pro.
Freestyle riding requires a sturdy bike. There are five disciplines within freestyle; Street, Park, Trails, Vert and Flatland.
|Making use of urban surroundings|
Street riding involves the use of public urban areas to perform tricks, jumps and grinds. It’s less organized and competitive than other styles.
Street bikes have evolved to employ steeper seat and head angles than bikes used for bigger jumps. They may be built with shorter wheelbases.
These features combine to make them more agile for trick-riding but less steady at high speeds or when landing big-air moves.
Trails and Dirt-Jumping
|At the dirt jump track|
Trails riding involves fluid movement through a series of dirt-jumps, performing tricks that require considerable risk and skill.
Bikes used for this purpose will have a longer, more stable wheelbase than a street or flatland BMX.
They usually use a single rear brake and might be fitted with a Gyro™ detangler to allow for bar-spins, tail-whips and similar tricks.
Vert riding involves big-air moves performed in a half-pipe (or ‘vert ramp’). High speeds are achieved through momentum.
Compared to other freestyle types, vert bikes are built with longer chainstays that contribute to a longer wheelbase and increased stability.
Vert bikes often have two or four pegs, to enable riders to stall on or grind along coping. Coping refers to the steel bars placed along each lip of a half-pipe.
Vert bikes need to be strong.
‘Park’ refers to skatepark riding, although many modern parks are also designed to accommodate BMX riders.
Outdoor parks are usually made of concrete. Many indoor venues are built from wood. Parks incorporate bowls, pools, quarter-pipes, coping, rails and various kinds of jumps.
Riders in skateparks often use pegs and may use one or no brakes. Depending on a rider’s style, their bike may more closely resemble a trail or street bike. Many riders customize to combine characteristics of both.
Flatland is one of the most distinct BMX styles and therefore requires a very particular type of bike. Flatland is performed on a level surface and involves highly technical tricks that see the rider manipulating their bike in every conceivable way allowed by the imagination.
Very little jumping or grinding is involved in traditional flatland. However, flatland riding influences other disciplines and continues to be integrated into street riding at higher and higher levels.
These bikes use a taller seatpost than other BMXs.
Flatland bikes have zero° fork offset to ensure that there is a direct line through the head tube to the fork axle. Wheelbases are short. These factors allow for a nimble, agile ride.
Most flatlanders have four pegs and may use two, one or even no brakes. Brakes are fed through a Gyro™ detangler to allow 360° rotation of the handlebars and bike. Freecoaster hubs have become standard.
Types of BMX Bike
Race bikes are designed to maintain stability at high speeds. For this reason, they feature slacker head angles and longer wheelbases than their freestyle cousins.
Compared to other BMXs, race bike geometry places the rider further over the rear end of their bike.
|An affordable alloy race bike
with a chromoly fork
Race frames are lightweight yet strong. Unlike steel freestyle bikes, tubing can be flattened or ovalized.
Aluminum is the most prevalent and affordable material of choice for a mid-range bike. Frames are often coupled with a chromoly or carbon fiber fork to absorb vibration and increase comfort.
High-end carbon fiber options are also available. These bikes are lighter than alloy framed bikes and may be more comfortable.
Race forks are usually made of chromoly steel or carbon fiber. Some beginner bikes use hi-tensile steel.
|Chromoly fork, alloy frame||Carbon fork, alloy frame|
Forks are offset to increase stability.
For most race bikes, 20” wheels are standard. Cruiser class race bikes use 24″ wheels.
|Most race bikes use 20″ wheels||Cruiser class racers use 24″ wheels|
Race bike rims and tires are narrower than those on freestyle bikes.
Full-sized Pro models usually use 36 spokes per wheel while smaller models often use 28 hole rims. Freewheel hubs are used, with a ⅜” axle.
|A micro racer with 1″ tires on 18″ wheels|
On full-size bikes, tires are usually around 1.75” wide.
On smaller sizes, tires can be as narrow as 1″, while 1⅛” tires are common.
On intermediate sizes, 1⅜”, 1.5” and 1.6” widths are used.
Race tires are considerably more narrow than freestyle tires and need to be inflatable to pressures as high as 100 psi.
Tread is low-profile for speed but ample for cornering and traction on dirt courses.
Race bikes use a single rear brake. This is usually a strong V-brake or disc brake.
|V-brake: Robust and simple||Disc brake: Powerful bite|
Disc brakes are specced on higher-end bikes but are becoming more common and more affordable.
|Specced on a new bike:
8″ rise handlebar, 50 mm stem
On full-sized Pro bikes, handlebars vary from 5” to 9” high and between 26” and 29” wide. Sizes below Pro often use lower rise bars, as small as 2.5″.
Cruiser class bikes require less bar rise as frames are taller than on 20” bikes.
On new bikes, most stems are around 50 mm long and made from aluminum.
To save weight, most seats are usually small and light.
They’re most useful as a steering aid or to protect the rider on landing jumps. For more details, please refer to our section on components (below).
Racers rarely use seats to sit on.
|The standard 44/16 race ratio|
The standard ratio is 44/16 (44 tooth chainring and 16 tooth driver), offering roughly 55 gear inches. This is the classic and current standard on race bikes.
Compared to a 25 tooth freestyle sprocket, a relatively large 44 tooth chainring distributes pedal power across more chainring teeth and chain links. They’re safer when ramping up to put the pedal down as the race gates open.
Race cranks are longer on full-size race bikes than on freestyle bikes. 175 to 180 mm is average.
For most beginners and younger riders who want a general-use BMX for knocking-about, a freestyle bike is the most versatile choice.
Options start at very affordable prices, particularly with full or partial hi-tensile frames.
Freestyle bikes are the best BMX option for riders who are undecided as to which BMX suits them best.
In general, freestyle bikes have shorter chainstays and wheelbases than race bikes. This aids maneuverability and agility when pulling stunts and tricks.
As previously mentioned, there are differences between frames that are better suited to street, vert, park and trail riding. However, many new bikes will ride well in some or all of these disciplines.
Top-tubes on full-size bikes are 20” to 22” long on average.
Chromoly steel is the way to go. It’s strong and compliant. Chromoly handles big hits and has weight advantages over Hi-tensile steel. It won’t crack and can be affordably repaired, unlike aluminum.
|Chromoly freestyle frame||Chromoly freestyle fork|
Tough forks are made of chromoly steel. Beginner rigs might use hi-ten. They’re built beefy.
|36h wheel with a 10 mm axle and 2.4″ tire|
36 spoke wheels are standard. Seek wide, double-wall rims between 34 mm and 38 mm wide.
A 14 mm axle is standard on a rear wheel. Front wheels use a 10 mm or 14 mm option.
Tires for street and ramp use are usually grippy but smooth or semi-slick. Tread is low-profile.
Freestyle tires are fatter than race tires at 2.2” to 2.5” wide.
Dirt jump tires are often more knobby, to grip loose surfaces.
|U-brake, mounted beneath seat-stays|
When freestyle riders run a brake, it’s usually a single rear U-brake (also known as a ‘990™-style’ brake, referring to the popular Dia-Compe™ model).
U-brakes are less obtrusive than V-brakes, keeping them out of the way during tricks and reducing the chance of snagging on clothes.
Some kids’ BMXs and low-end bikes may use two caliper brakes.
|Brakeless riding at an advanced level|
Caliper brakes are fine for everyday use by kids but aren’t the safest or toughest for trick use.
Many advanced riders do not run brakes at all.
For some riders, brake detanglers such as Gyro™s are popular. These mechanisms allow for 360° rotation of handlebars when performing bar-spins, tail-whips and similar tricks. They are only needed when a rear brake is used.
Freestyle handlebars are tall, to make spins and handling easier. They usually sit between 8” to 10” high and 28” to 30” wide.
|Stem: 48 mm reach, 8 mm rise||Handlebar: 29.5″ W x 9.7″ H|
A reach of around 50 mm is standard, while rise can vary a lot. Between 30 and 36 mm is common, but a larger range can definitely be found. Many stems can be flipped upside down to offer radically different rise or drop.
Freestyle seats are wider and more padded than race seats. But they’re still small compared to the seats used on other bike types, where you’d be seated for a large part of your ride.
Extra width ensures against injury on landing impacts, while aiding grip on no-handed tricks.
There are a number of different seat standards available for freestyle bikes (see components).
‘Microdrive’ drivetrains are now standard on modern freestyle bikes. These use a smaller sprocket (chainring) and cog (rear sprocket) than race bikes. This allows for maximal clearance and less obtrusion when performing tricks, stunts etc.
Small sprockets are lighter and less likely to bend than larger options.
|Microdrive drivetrain with a 25 tooth chainring and 9 tooth driver|
On new freestyle bikes, the standard ratio is 25/9, with a 25 tooth sprocket and a 9 tooth cog, giving 55 gear inches. Some riders may choose to modify this to achieve as much (or more than) 62 gear inches, with sprockets up to 28t and drivers as small as 7t.
|Complete with 2x pegs and 160 mm cranks|
Freestyle cranks are shorter than race cranks.
Shorter cranks provide extra clearance and avoid scraping on grinds, coping and such.
Freestyle bikes may have two, four or no pegs, depending on a rider’s preference for certain tricks.
Pegs are great for grinding rails and coping but they also open up riders to performing other tricks.
|This bike has an 18.7″ top-tube
and 13.4″ chainstays
Flatland bike frames are more compact than standard street and freestyle frames.
Top-tubes sit between 18.9” and 19.5” and chainstays between 12.5” and 13.5” in length.
Top-tubes are low to allow clearance for maneuvers.
Steep 75° head tube and 71° seat-tube angles are standard.
Forks have zero° offset to create a direct line from stem to axle, providing agile and sharp steering.
Frames are strong, reinforced and built from sturdy chromoly tubing. They often have tabs and/or mounts to attach a brake detangler (Gyro™) setup.
Forks are usually made of chromoly steel. A lot of weight is put on a bike’s fork in flatland; during nose wheelies, manuals and endos. They need to be strong.
Flatland forks usually have no offset, zero°. They are dead straight for direct handling when rotating the bars or spinning on the front wheel.
Wheels are always 20” and almost always use 36 spokes. 48 spoke wheels were popular in the past but with strong, modern double-wall rims the extra weight is no longer necessary.
Tire widths usually hover between 1.75” and 1.95”.
They must inflate to the high pressures required by this discipline (between 100 and 110 psi).
Treads are low-profile and almost slick. Complex treads aid lateral movement and rotation.
|16″ model with dual U-brakes and a Gyro™|
Flatland riders use U-brakes in the 990™ (or similar) style. These are unobtrusive and are less likely to cause injury or snag on clothes.
Running two brakes is a common setup, especially for beginners.
As skills progress, some riders choose to remove the rear brake. Other riders find their trick options limited by removing brakes.
Some virtuosic riders eventually move on to riding brakeless. The number of brakes run is up to preference.
When a rear brake is used, flatlanders set it up with a brake detangler device (Gyro™).
|Pro rider Matthias Dandois rides brakeless||Gyro™ setup: tabs on frame visible|
Brake detanglers were pioneered on flatland bikes and made famous under the Gyro™ trademark. Many street riders now use them too. These devices are used to route a rear brake cable past a bike’s stem to allow for 360° rotation of your bike and/or handlebars.
|8.8″ bars, flangeless grips, 40 mm stem|
Flatland bars are relatively tall, with 8.5” to 10” of rise, to allow for ample reach and maneuverability.
Generous widths of 27.5” to 31.0” are available on uncut handlebars to aid leverage for performing bar-spins and similar moves.
Most riders trim new bars to achieve a custom fit.
Both 2 and 4-piece bars are used. Some riders prefer the straight angles of a 4-piece bar.
Upsweep is moderate, at 2° to 3°. Backsweep usually sits between 5° and 12°.
Flatland grips are often straight, no flange, to permit hands to easily slide on and off handlebars.
Reach is up to preference, but can be as short as 28 mm or as long as the standard 50 mm.
|Flatland seat with an underside hand-grip|
Many standard freestyle seats suit flatland. Purpose-made seats are usually short and of moderate width, so they can be gripped by the legs or thighs.
Several models are shaped to be used as a hand grip. Most options use a pivotal seatpost.
Flatland seatposts are longer and positioned higher than those on other BMX bikes.
A long seatpost places a bike’s seat at a similar height to its handlebars. At this height, it can be used as an extra handle when performing tricks.
Flatlanders are not landing jumps, so a higher seat is not a big injury hazard.
Many modern seatposts use the pivotal system but combo seat+seatpost options are also popular.
Flatland bikes have four pegs, two on the front wheel and two on the back. For more tricks!
Flatland drivetrains are similar to other freestyle drivetrains, with the exception that a modern flatland rear hub is always a freecoaster.
The standard 25 tooth sprocket / 9 tooth driver is most common.
Sprockets are available in sizes from 18 to 28 teeth.
|Freecoaster hub (cutaway shows internals)|
The freecoaster hub was pioneered on flatland bikes and is pretty much the universal choice for flatlanders.
This type of hub allows riders to roll backwards without pedaling in reverse. A freecoaster makes it easier to look toward the rear of the bike while riding ‘fakie’.
|A 2-piece titanium crankset|
Cranks undergo a lot of stress. Your most affordable option is 3-piece chromoly. For titanium, 2 or 3-piece will hold up.
Crank length depends on frame size but they’ll probably be shorter than those on race bikes, with more options available in 165 mm than other sizes.
Sizing and Size Categories
Freestyle, General-Use and Kids’ BMX Bikes
Rider height is the most important consideration when choosing the right size BMX. Most teenagers and adults will be happy with an off-the-shelf complete BMX with 20” wheels.
|Adults’ 2XL BMX. 20″ wheels and 21.25″ top-tube||Kids’ BMX with 20″ wheels and 20.3″ top-tube|
After some ride experience or following a growth spurt, riders might modify their bike by swapping out the stem, cranks or handlebars, thus fine-tuning it to suit their own body geometry.
|This beast uses 29″ wheels
and fat 2.8″ tires!
The standard BMX wheel size is 20” for street, ramp, vert, dirt and flatland use.
24″ and 26″ cruisers have been widely available for decades.
BMXs now come in a wide range of wheel sizes. Bikes are available to suit everyone, from small kids through to adults who like to roll on bigger bikes with that BMX feel.
This is a general guideline of how BMX wheel sizes fit rider heights:
12” → Toddlers
These little bikes fit riders from roughly 2’9” to 3’4” (33″ to 40″) in height.
14” → Toddlers and Kids
These bikes suit taller toddlers and shorter 5 to 6-year-olds.
16” → First ‘Real’ BMX?
This is the size that many young riders are using to get into real BMX riding. These bikes fit riders from around 3’5” to 4’0”.
They should resemble a downscaled version of a full-size BMX. Most riders are between 5 and 8 years of age.
18” → The In-between Size
18” wheels are a less common size that is often overlooked by riders and parents.
Many kids move straight on to a 20” rig. 18″ wheels suit riders from around 6 to 9 years of age.
20” → Standard BMX Size for Older Kids and Adults
Kids from as young as 7 might choose a 20” BMX for a casual ride, but from 10 years they are big enough to use them to perform jumps and tricks.
20″ is the wheel size used by teenage and adult freestyle riders at the skate park, on the street, over trails and through dirt jumps.
22” → Larger Size for Taller Freestyle Riders
This is a size that some manufacturers have recently embraced. 22″ wheels are still small enough to be handled with agility.
Longer frames use 22″ wheels on true freestyle BMX bikes that suit riders 6’0” and above.
24” → Bigger Freestyle and BMX Cruisers
Some 24” bikes are just scaled-up from 20” models, for bigger and beefier riders or those who want to go faster.
Some 24″ bikes are dubbed ‘cruisers’ and are intended for casual riding. 24″ bikes are recommended for riders over 5’2”.
26” → Bigger BMX Cruisers
This is the same size as older mountain bike wheels and some beach cruisers.
Some riders might be tough enough to throw a 26-incher around like a standard BMX, but they’re often chosen as casual rides for city use. For some folks, this size makes for a good wheelie-bike.
27.5” → Cruisers for Teens and Adults
27.5” wheels are the same size as the current mountain bike standard. 27.5” BMXs aren’t super-common but there are a few new models out there.
27.5″ bikes are popular with wheelie aficionados and urban riders.
29” → The Biggest BMX Cruiser
29ers have a cult following with those who like to spend all day on the back wheel. But you won’t find many riders jumping these rigs. They suit tall teens and adults.
The larger size BMXs in 26”, 27.5” and 29” sizes are great for Dads and Mums who don’t want to give up on BMX and who love to ride alongside their kids as they get into BMX themselves.
Race BMX Sizes
|Cruiser class racer with 24″ wheels|
Race BMXs come in defined size categories for riders of different ages and heights.
Official race bikes in the Novice, Intermediate, Girl and Expert categories all use 20” wheels.
In the ‘Cruiser’ class all bikes use 24” wheels.
These are the size categories for bikes with 20” wheels:
- Rider Height: 4’0” or under
- Cranks: 120 to 140 mm
- Tires: 18 x 1″ to 20 x 1⅛”
- Age: 4 to 6 Years
- Top-Tube Length: 15.0” to 16.5″
- Rider Height: 4” to 4’6”
- Cranks: 130 to 145 mm
- Tires: 20 x 1⅛” to 20 x 1⅜”
- Age: 4 to 7 Years
- Top-Tube Length: 16.0” to 18.0”
- Rider Height: 4’4” to 4’10”
- Cranks: 145 to 165 mm
- Tires: 20 x 1⅛” to 20 x 1⅜”
- Age: 6 to 9 Years
- Top-Tube Length: 17.0” to 18.5”
- Rider Height: 4’8” to 5’4”
- Cranks: 155 to 170 mm
- Tires: 20 x 1⅜” / 20 x 1.5” / 20 x 1.75” (sometimes 1.6” upfront and 1.4” on the rear)
- Age: 9 to 13 Years
- Top-Tube Length: 18.5” to 20.0”
- Rider Height: 5’4” to 6’0”
- Cranks: 175 to 180 mm
- Tires: 20 x 1.75” – 20 x 2.0″ Sometimes wider up-front (e.g. 1.95” front, 1.75” rear)
- Age: 12 to Adult
- Top-Tube Length: 20.0” to 21.0”
Pro XL, XXL & XXXL
|Pro XL||Pro XXL (above). Pro XXXL (below)|
- Rider Height: Taller adults – 5’10” and above
- Cranks: 175 to 180 mm
- Tires: Similar to Pro
- Age: Taller teens and adults
- Top-Tube Length: 21.0” to 22.25”
BMX components are built tough and simple. Riders seek out freestyle bikes with ‘bombproof’ parts for use in skateparks, on dirt jumps, vert ramps or for street riding.
In the case of race bikes, they are light and agile, but still strong.
BMX riders have a preference for components that fulfill very specific requirements.
A few BMX components share some similarities with those on mountain bikes or single-speed bikes. But in general, BMX components display unique characteristics in the cycling world.
V-brakes are usually used as a rear brake on BMX race bikes. This is the same type that’s used for the front and rear brake on affordable commuter, hybrid and mountain bikes. Some children’s BMXs may use them for one or both brakes.
They are powerful, light and easy to maintain and adjust at home. V-brakes are not used by freestyle or flatland riders because they protrude too much during gnarly trick-riding.
|This bike comes equipped with
a mechanical disc brake
As they become more affordable, more new models are becoming available fitted with a disc brake.
There are two main types of disc brake; mechanical and hydraulic.
Like all rim brakes (caliper, V and U-brakes), mechanical disc brakes are actuated by a cable. This cable clamps brake pads onto a rotor. Compared to hydraulic disc brakes, this makes them easier to adjust and repair. They don’t use oil or fluid, and therefore they don’t require regular bleeding. On the downside, mechanical disc brakes are less powerful than hydraulics.
Hydraulic disc brakes are only fitted to high-end BMX race bikes and are the most powerful option available.
Hydraulic disc brakes use fluid or mineral oil in an enclosed system.
Installation and initial adjustment require specialist tools and skills. They require regular ‘bleeding’ using a ‘bleed kit’. For most owners, this is a job best left to bike mechanics at your local bike shop.
U-brakes / 990™s
This is a style of rim brake that you will only see on BMX bikes (and maybe a couple of early ‘90s mountain bikes). They are the standard on freestyle and flatland bikes.
The ‘990™’ was a particularly popular model made by the manufacturer Dia-Compe™. The term ‘990™-style’ has become synonymous with the U-brake even though this model has now been superseded.
U-brakes use two arms, similar to a caliper brake, but with the brake’s bosses attached directly to the frame or fork.
They’re not the most powerful brake in the world but they are the most suitable for the kind of riding that involves complex maneuvers. They protrude less than other types of brake and tend to have rounded outside edges.
They are the most suitable type of brake to set up with a brake detangler (aka Gyro™).
Detanglers / Gyro™s / Rotors
A detangler (or ‘rotor’) is a device that allows a bike’s rear brake cable to be routed in such a way that a 360° rotation of the bike’s handlebars is possible, without brake cables becoming tangled around the head-tube or handlebars.
They’re more commonly known by the name ‘Gyro™’, which is a model pioneered by the manufacturer Odyssey™.
A single cable is split into two cables that pull on either side of a disc, which is attached to the steerer tube. This disc is attached, via a lip, to another disc beneath it. This allows these discs to rotate 360° around one another. The lower disc is also attached to two sections of cable that feed into one, actuating the rear U-brake.
They are invaluable to flatland riders and freestyle riders who want to run a back brake, as they make tricks such as bar-spins and tail-whips possible. A detangler isn’t needed for a front brake cable, which can be routed through a bike’s headtube to avoid tangling.
Although detanglers complicate brake setup and maintenance, they are indispensable to any flatland or freestyle rider that hones their craft with the use of a rear brake.
A number of new BMX bikes come fit with a detangler, which will save you the trouble of having to fit one yourself. Some frames do not have the tabs needed to fit one. Keep this in mind when looking at new bikes.
Removing the concern of tangling cables can offer peace of mind.
Brakes: Number and Location
Single Rear Brake
This is the standard choice on race bikes, where the brake is a V-brake or disc brake. Some vert and park riders may choose to run a single rear U-brake (‘990™-style’).
|Rear U-brake only: Freestyle||Front U-brake only: Flatland|
Single Front Brake
This configuration is sometimes used on flatland bikes, where a rider’s skills have evolved past the need for a rear brake. The brake is usually a U-brake.
Front and Rear Brakes
|This complete flatland bike arrives fitted with front and rear U-brakes|
Dual brakes are very popular on flatland bikes, to give riders maximum control when performing a wide range of tricks. Both are U-brake / 990™-style brakes. The rear brake cable is routed through a detangler / Gyro™ device to allow 360° handlebar rotation.
Few freestyle riders choose to run two brakes as they become an obstacle and are often unnecessary. This is not the case with children’s BMXs, where dual brakes can increase safety. However, grabbing the front brake at speed can cause a rider to flip straight over their handlebars.
Brakeless / No Brakes
For the kind of ‘street’ or skate park riding that involves a lot of tricks and grinds, many experienced riders don’t use brakes at all. Obviously, this isn’t recommended if your bike is going to be ridden on a road or in a crowded public area.
|This brakeless bike is shipped with an
optional rear U-brake
When it comes to achieving a smooth flow and maintaining momentum, brake cables can just act as an encumbrance. Sometimes, brake arms can snag on clothes or cause injury during a crash.
New riders often practice with a rear brake before moving to brakeless riding.
Some expert flatlanders perform complex tricks without using any brakes! Such virtuosic riders are able to stall, manual and nose manual without the need for brakes. To be honest, this is a level of riding only open to zen BMX masters.
BMX handlebars are taller than handlebars used on most other bikes, to compensate for the smaller frames.
Freestyle bars tend to be available in slightly taller options than race bikes, as the extra reach aids maneuverability.
Some riders use narrow handlebar sections for increased control on spins and X-ups.
Freestyle handlebars come in two main styles, ‘2-piece’ and ‘4-piece’. The names are self-explanatory and refer to the construction of the bars:
|2-piece handlebar||4-piece handlebar|
A lot of folks see the differences as purely aesthetic but some riders believe that 4-piece bars are stronger, stiffer and less likely to obstruct the knees. Others say that with more joins, 4-piece bars have more points at which to crack. The debate goes on.
Chromoly: Due to its strength and high degree of shock-absorbance, chromoly is the most common choice for freestyle bars. It’s also widely used on race bikes.
|Carbon race bar||Chromoly freestyle bar||Alloy race bar|
Aluminum: Aluminum bars may be used on some race bikes but it’s a rare choice, due to how jarring it can be.
Carbon Fiber: Some high-end, weight-conscious race bikes may be fitted with carbon fiber bars. These will definitely add a lot to the cost of a bike.
Race and freestyle stems are usually machined from 6061 (cheaper) or 7075 (pricier) aluminum and offer close to 50 mm of reach on most new full-size bikes.
|6061 Alloy top-load freestyle stem||6061 Alloy front-load race stem||Titanium front-load stem|
Other lengths are available on aftermarket stems. Freestyle stems will be beefier and heavier than their race counterparts.
Seats are used less in BMX than in other cycling disciplines. This is why they are so small. Even when used by tall kids and adults, seats are set low. This keeps them out of the way when landing jumps. Even though BMX seats aren’t used as an all-day perch (as they are on a mountain, road or commuter bike), they still play an important role.
|Racers pedal out of the seat…||…and get low on landings|
On freestyle bikes, a seat can be gripped by legs or thighs to perform no-handed tricks. Flatlanders grip the underside of a seat to use it as a handle. Apart from that, a padded seat keeps you from injuring yourself on the frame when you slam down hard after landing a jump. For race bikes, seats are light and minimal.
|Kids pedal while seated||A low seat allows more tricks|
For smaller kids who ride their BMX everywhere, a standard seat at a comfortable height is the best bet.
These are the seat styles used on BMX bikes:
The pivotal seat and seatpost system is only used on BMX bikes. Pivotal seats are only compatible with pivotal seatposts.
Adjustment is made by rotating the seat forward or aft to align a series of grooves between the underside of the seat and the top of the seatpost.
These seats are attached to the seatpost and adjusted via a bolt that is accessed through a flap in the top of the seat cover.
They are tough, simple and easy to adjust. Currently, they are the most popular freestyle BMX seat.
The tripod system is the most recent freestyle BMX standard.
A stable attachment system uses three bolts in a triangular arrangement, bolted directly to a plate on the seat’s underside.
It’s strong and simple but offers limited adjustment without owning a range of seatposts.
With integrated systems, the seatpost is part of the bike’s frame and is set at a fixed height.
As you might imagine, it’s never been a system that gained much popularity.
This is the same as the system used on traditional models and some cheaper new bikes.
The seatpost slides into the seat ‘guts’, where mechanisms clamp the seat to the seatpost and allow adjustment, usually with a spanner.
This system works well but it’s a bit heavy and clunky for anything but kids’ bikes.
It was the ‘standard’ system used on the first BMX bikes.
Railed / Micro-Adjust
This is similar to the seatpost and saddle system used on most road, mountain and commuter bikes.
The seat has two rails and uses bolts to adjust a clamp along these rails. These are sometimes used on race bikes and older-school BMXs.
Combo systems combine the seatpost and seat in one piece. This saves weight and keeps things simple.
Adjustment options are limited but that’s no deal-breaker for race bikes because those seats ain’t for sitting on.
Also available in freestyle options.
|This bike’s chromoly fork is drilled
to attach a brake
BMX forks are always rigid and never use suspension.
Quite a few new bikes come with a fork that’s drilled to attach a brake. You’ll want to make sure this is the case on small kids’ bikes and if you’re learning flatland. Some bikes might be sold with a fork that isn’t drilled, so keep that in mind.
For a starter or kids’ freestyle bike, hi-tensile steel will do a fine job. It will be more jarring than chromoly, which is the material of choice if you can afford it.
Chromoly forks are usually more resilient, lighter and exhibit superior pliancy.
|This chromoly fork is not drilled to attach a brake|
Lower-cost and beginner race bikes often employ a chromoly fork with an aluminum frame. Chromoly does a fine job to start with but as you progress you’ll want to shed weight. If your budget’s bigger, aim for a new race bike with a carbon fiber fork.
|A rider pedals in reverse to complete a
‘half-cab’, using a cassette
There are two main types of rear hubs used on BMX bikes; freecoasters and cassettes. Cassettes are standard on race bikes, where tricks aren’t a concern. Some freestyle riders also prefer them.
The popularity of freecoasters flourished with their adoption by flatland riders. These days, they’re also ridden by many street and park riders.
The choice is up to personal preference and will be influenced by your main ride style.
Most ‘beginner’ bikes are fitted with cassette hubs. But affordable new bikes, fitted with freecoasters, are also available.
All race BMXs use a cassette hub. Before the freecoaster, they were also the traditional choice for freestyle hubs.
|Freestyle cassette hub|
Sealed cassette hubs are now the standard on new BMXs.
Many freestyle riders are comfortable with a cassette. When using a cassette, riders need to make one full backwards rotation of the pedals when traveling in reverse, in order to half-cab.
Freecoasters are the hub of choice for flatlanders. They have been for some time. This is because flatlanders have always spent quite a bit of time moving in reverse.
A freecoaster moves a clutch in or out depending on the direction that your rear hub is moving. When the pedals rotate in reverse this clutch disengages, meaning that you can continue to roll backwards without pedaling. A freecoaster makes it easier to travel distances in reverse while looking backwards.
The popularity of the freecoaster is increasing. They are becoming more common on new freestyle bikes. There is some ‘slack’ present when moving backwards and this is a detracting factor for riders who prefer cassettes.
The Planetary Freecoaster
An even more specialized hub has recently emerged on the scene.
The planetary freecoaster claims no slack and engages through wheel movement, instead of hub movement.
The standard BMX wheel size is 20”. They are used in all race bike classes, except cruisers. Most freestyle and flatland bikes also use 20” wheels.
|Standard 20″ wheels||New 22″ wheel standard|
A new, rarer 22” wheel size is emerging on freestyle bikes. This standard is aimed at big dudes and gals. If you’re over 6’0”, you might want to seek one out.
Bikes with wheels smaller than 20” can be found for kids. This includes 12”, 14”, 16” and 18” options. A few micro race bikes use 18” wheels.
|Are 36″ wheels the future?|
In cruiser class, race bikes use 24” wheels. Freestyle bikes are also available in 24” but are heavier, less agile and somewhat harder to maneuver for street or park riding.
Any bike with 26”, 27.5” or 29” wheels is known as a ‘BMX cruiser’ and is usually aimed at urban use. Some folks might jump a 26-incher but these bigger bikes are usually used for cruising around town while pulling wheelies and manuals.
|Cross-section of a double-wall rim|
Strong BMX rims are constructed with two horizontal walls built into them. These rims are known as ‘double-wall’ and are the best option for anyone planning on subjecting their bike to any amount of abuse.
Double-wall rims are a good idea, even if you’re just starting to learn tricks. You’re bound to make the occasional misstep.
Single-wall rims can be found on kids’ bikes and cheapo BMXs. They’re only safe if you’re mostly rolling around town, without any plans to drop off ledges or big curbs. Jumping is not advised on these rims. They will bend over time.
If the technical specifications of a bike don’t mention double-wall rims, it’s safe to assume they are single-wall.
Rim seams can be pinned or welded.
Pinned rims are held together at the seam with pins, which tend to weaken easily over time. Most single-wall rims are pinned.
Welded rims are much stronger and more durable. They are the preferred choice if you intend to progress in BMX.
|28 hole rim and wheel on a race bike|
Most freestyle bikes use 36 spokes on their front and rear wheels.
Some lightweight race BMXs use 28 hole rims and hubs. This can be enough when riders are light and the main priority is speed.
Wheels are also available with 48 spokes but these were more popular on older bikes.
’48 hole’ rims are reserved for the roughest and heaviest riders.
|Riders drop off rooftops on this 48-hole rim|
If you frequently ride off the roof of your house and into your empty pool, choose double-wall, 48-hole rims.
As strong rims, hubs and spokes are able to be built at lighter and lighter weights, 36 hole wheels are ample for most riders.
Cutting-edge, lightweight rims are now available for race bikes with only 24 spokes. These are made of carbon fiber
|10 mm axle (outside and inside a front hub)|
Axle sizes vary depending on the type of bike you’re looking for and the type of riding you’ll be doing. There are two main sizes of axle. ⅜” is an older term for a size that is equal to 10 mm. They are interchangeable. ⅜” axles can be used in 10 mm dropouts and vice versa.
- ⅜” aka 10 mm. This is the narrower width.
- 14 mm is the wider, stronger width usually used on rear freestyle wheels.
|⅜” axle visible in a lightweight race front hub|
- Front: ⅜”
- Rear: ⅜”
Race bikes use ⅜” axles to save weight.
- Front: 10 mm axles are often used to save weight. 14 mm options are also available.
- Rear – 14 mm axles are the standard, to withstand impacts.
|This 14mm axle is made of titanium|
Pegs are available to fit both 10 mm and 14 mm axles.
|14mm chromoly axle|
- Front – ⅜” axles are used on most wheels.
- Rear – 14 mm and ⅜” options are popular.
Flatland bikes take fewer hits and drops than freestyle bikes.
Rear-facing horizontal fork ends are a defining characteristic of BMX frames.
A rear fork end is the slot that your rear wheel’s axle slides into. Bolts are then tightened onto your axle’s threaded ends, to hold your wheel firmly at the desired position.
Horizontal fork-ends are perfect for adjusting chain tension, simply by sliding the axle forward or backward.
These are the same style as used on many dedicated single-speed frames, including those made for track bikes.
BMX cranks use 3-piece, 2-piece or 1-piece construction.
3-piece cranks are the most common type specced on new BMX bikes. They use two separate crank arms and a spindle.
3-piece cranks are strong and affordable. If damage occurs to one arm or the spindle, these can be replaced.
2-piece cranks have one arm attached to the spindle. This spindle is usually wider and lighter than those used on 3-piece cranks.
You should be able to replace the separate arms of a 2-piece crank assembly if one is damaged. However, some riders report that they are unable to replace drive side (spindle) arms.
Due to their light weight, 2-piece cranks are more common on race bikes than freestyle rigs.
1-piece options are used on the cheapest kids’ bikes. You’ll want to avoid these on any BMX for any age of rider. The single piece threads through the bottom bracket and incorporates both crank arms and the spindle.
1-piece cranks rarely use sealed cartridge bearings and are easy to bend. If this happens, the whole assembly must be replaced.
Always aim for 2 or 3-piece cranks on your new BMX.
Sprockets aka Chainrings
|44t and 25t chainrings|
The term ‘sprocket’ is usually used to refer to freestyle BMX chainrings. On race bikes, ‘chainring’ is more common.
They are usually made of 6061 or 7075 aluminum.
New bikes are almost always sold with standard-sized sprockets and chainrings.
For race bikes, chainrings have 44 teeth. For freestyle, sprockets have 25.
Drivers, Cassettes, Freecoasters & Freewheels
Rear BMX hubs can use a cassette, freecoaster mechanism or freewheel.
|Cassette hub and driver|
Cassette hubs can use a removable and replaceable cog.
They can also use a one-piece driver that incorporates a sprocket and ratchet mechanism in a single unit. This design allows for fewer teeth and smaller sprockets than can be made in cog or freewheel form. Drivers may use as few as 7 teeth.
Cassette drivers are replaceable but more costly to swap out than a separate cog.
|Cassette hub and removable cog|
On cassette drivers, the freewheel is internal and sealed within the hub. They are used with both race and freestyle hubs. On race bikes, a 16 tooth driver is standard. On new freestyle bikes, 9 teeth is the most common spec.
Compared to a freecoaster, some riders report that it can be more difficult to find the right foot position in regard to crank rotation, while performing and landing tricks and stunts.
Freecoaster hubs use a screw-in driver. They use an internal clutch that is engaged when the pedals and hub are turned forward. The clutch disengages when pedals are turned in reverse. Freecoaster mechanisms are more complex than cassettes and are more expensive for this reason.
Removable freewheels were the old-school standard. A freewheel is a sprocket with its own bearing housing and pawls. They screw onto a threaded hub and are only available with 13 or more teeth.
They are mostly superseded by freecoaster and cassette hubs but are still popular on adult single-speed bikes.
This is the standard width for freestyle BMX chains. It’s the same width as used on full-size single-speed bikes.
This is a narrower width that is common on race bikes.
Half-link chains are common on race and freestyle BMX bikes. They allow for the removal of a single link, whereas two links need to be removed on a standard chain.
Half-links allow you to fine-tune the tension of your chain and placement of your rear wheel more closely.
The price of a new bike will be increased due to:
- The quality of components.
- The presence of name-brand parts.
- How light parts are, while still retaining strength and durability.
Even though BMXs are simple, it’s still true that there’s a big difference between a death-trap and a well-built bike.
By informing yourself, you can find a bike that lets you ride hard without worry, and it doesn’t need to be expensive.
Phew. That’s enough reading, time to grab a bike and ride!
Choose wisely and roll on.
- USA BMX, The Track
- Union Cycliste Internationale, BMX Track Guide
- Bart de Jong, Bicycle Motocross in Holland in 1956!
- Eric Rothenbusch, BMX History 1897-1979
- Mike Carruth, A Partial History of the Sport of BMX Racing
- Gerrit Does, History of BMX (1968 – 1974)
- Gerrit Does, History of Dutch FX in the ’50s
- Jonathan Weiss, Conservation, Recreation, Education and Transportation Expo Greenway
- Ted Rogers, Born in West LA –
LABAC Member Traces the Beginnings of BMX to a Westside Park
- Kurt Hohberger, The Evolutions of the Seat Post Clamp
- Hans Dersch, Difference Between BMX & Mountain Bikes
- Relja Novović, Bicycle Drive Chain Standard Dimensions
- Alfredo Mancuso, The Best BMX Rim Guide
- Alfredo Mancuso, Product Guide: Freecoaster vs Cassette 101 and Pros & Cons
- Bartels Birk, Rim Construction – Single Wall vs Double Wall & Braking Surfaces
- Jonathan D. Septer, What Is Better: Big or Small Front Sprocket on a BMX Bike?
- Pedallers, The Difference Between a BMX Freecoaster and a Cassette
- Mike C, Frequently Asked Questions About Flatland