Essay: The history of BMX

Overview
The real history of BMX started in the early 1970s when some children began racing their bicycles on dirt tracks in Southern California, drawing inspiration from the motocross superstars of the time. Moreover, it was in the middle of 1970s that BMX racing was a phenomenon and by the middle of that decade which the sport achieved a critical mass, and manufacturers began creating bicycles designed especially for the sport. In addition, since that time BMX has been used as phenomenal sport bicycle.
In addition, this sport has two distinct genres  ̶  racing and freestyle. Racing is where it all began as far as BMX is concerned, while freestyle evolved as a new breed of riders started specialising in tricks and bike handling as opposed to banging bars at the race track.
Therefore, in April 1981 the International BMX Federation was founded, and their first World Championships were held in 1982. Since January 1993 BMX has been integrated into the Union Cyclist International (UCI).
BMX Designer
The picture below illustrates a simply BMX bicycle which is used for freestyle sport. Further, BMX bicycles are typically based around 20’’ wheels, a rigid frame and fork alongside high-rise handlebars and a single cassette gear.
Description of BMX
Size
BMXs are small in size which makes them light and easy to handle. A great number of BMX wheels are 20’’ in size, top tubes which can range between 20’’-20.75’’, handlebar height and width which can also differ.
Durability
BMXs will encounter many physical abuse, which unfortunately can give them a relatively short life span, but their parts are relatively cheap to replace.
Frames
The lightest BMXs are made of aluminium, or super light chromoly which is a steel alloy. In addition, racing BMX bicycles tend to have aluminium frames, as the metal is lighter weight means manufacturers can use larger tube diameters and bigger weld surfaces. As a result, you obtain a stiffer feel that is ideal for racing, also the bicycles tend to offer a longer wheelbase and lengthier, low top tube that helps with stability at speed.
Nevertheless, freestyle BMX bicycles’ frame are typically made of steel. Moreover, they are heavier, cheaper, high tensile steel which is typically used in entry-level models. However, chromoly is slightly lighter but, most importantly, stronger.
Forks
BMX in its feature has rigid forks. High-end race bicycles may use pricey carbon fibre forks but the vast majority opt for good old-fashioned steel. Further, 4013 chromoly is preferable for its superb strength to weight benefits, but high tensile material is more predominant lower down the price range.
Brakes
BMX bicycle are sold with two brakes by law, but although it, racers usually remove the front one because a BMX race track is majority about being as fast and smooth as possible, with no steep sections requiring speed to be scrubbed in a hurry, the front stopper is ditched to save weight. The rear brake tends to be a V-style number because they are powerful and light.
Freestyle BMX bicycles will feature a front and rear brake and, on some models, a gyro. This is a combination of cups and bearings situated below the stem that allows the bars to be spun 360 degrees without tangling the brake cables.
Wheels and tyres
The vast majority feature a 36h alloy sealed bearing hub with a steel axle laced to a double wall rim. As a result, they offer superb strength. While knobbly tyres are ubiquitous on race bicycles as they offer good grip on loos surfaces. The front tyre is typically wider than the rear, to provide smoother handling, while the rear is thinner to allow a smaller contact point for snappier acceleration out if the gate.
Freestyle bicycles tend to feature more tarmac-orientated rubber for better grip on a mix of manmade surfaces.
Bars and stem
Two-piece steel bars are common in BMX. Further, higher-end bicycles will feature chromoly steel while cheaper numbers get high tensile material. Bar heights tend to average out at about eight inches, and widths fall somewhere within the 27in ballpark. Stems are usually stout, 50mm, front-loading, and four-bolt alloy numbers.
Cost
According to bike radar (n.d)  the average of the prices can vary around £200 for a decent entry-level BMX, £400 for mixed steel frame territory and £500 or more for a fully chromoly machine. Nevertheless, these prices can continue up towards £800 for a full pro-level bicycle.
BMX materials
Normally BMX bicycles are made of three materials that are aluminium, steel and titanium. In addition, with these materials are possible to figure out some parameter on bicycle such as density, yield strength, modulus of elasticity and strength to weight ratio.
Density is a measure of how heavy a material is within a certain size (volume). This is expressed as grams/cubic centimetre (g⁄〖cm〗^3 ) or pounds/ cubic inch (lb⁄〖in〗^3 ). It does not change for material grade or heat treat.
Yield Strength is a measure of a point of material failure. It is expressed in units of pressure (Pascal (Pa)) or (pounds/square inch (psi)). Yield Strength is very dependent on the material grade and heat treat.
Modulus of Elasticity is a measure of how springy (Flex) the material is. It is also expressed in units of pressure (Pascal (Pa)) or (pounds/square inch (psi)). It does not change for material grade or heat treat.
Strength to Weight Ratio (STWR) Yield strength divided by the density.
Aluminium
Density = 2.81  g⁄cc  (0.102  lb⁄〖in〗^3 )
Modulus of Elasticity = 71,700,000,000 Pa (10,400,000 psi)7075-T6
Yield Strength = 255,000,000 Pa (73,000 psi)7075-T6
STWR = 715,686 6061-T6 STWR=362,745
Aluminium is a commonly used material due to its ease of machining, cost and moderate strength. The grade makes a big difference in strength.
Steel (grade 4130)
Density =7.85  g⁄cc(0.284  lb⁄〖in〗^3 )
Modulus of Elasticity = 205,000,000,000 Pa (29,700,000 psi)
Yield Strength = 779,000,000 Pa (113,000 psi)
STWR = 397,887
This kind of BMX 4130 is a commonly used material for BMX frames due to its, low cost and high strength. Yield strength numbers for 4130 steel vary greatly due to many different heat treatments available. Numbers that I have presented above are for a relatively high strength heat treat, although density and modulus do not change.
Titanium (grade 6AL4V)
Density = 4.43  g⁄cc(0,160  lb⁄〖in〗^3 )
Modulus of Elasticity = 113,800,000,000 Pa (16,510,000 psi)
Yield Strength = 880,000,000 Pa (128,000 psi)
STWR =800,000
Titanium is usually a high cost upgrade for BMX components, but as you can see it has many benefits. It is lighter than steel but about the same strength. It will also flex more than steel for the same geometry. In addition, it is heavier and much stronger than aluminium. The biggest drawback to titanium is cost. On average, it is 4 times more expensive than aluminium and 10 times more expensive than steel.
Criteria
It has chosen Zodiac 2016 BMX bike to illustrate the criteria of a normal BMX bicycle.
Zodiac 2016 BMX Bike
Frame 4130 full crmo, tapered seat stay & chain stay, removable pivots and guides, invest cast dropout with integrated chain tensioner. 20.75″ top tube, 13.25″ chain stay, 75.5 degree head tube angle, 11.75″ bb height, 9″ stand over height
Handlebars full 4130 crmo 4pc bar, 9″ rise, 29.5 wide, 11 degree back sweep, 3 degree upsweep
Rear Brake SALTPLUS “Geo XL” alloy u-brake rear
Brake level SALTPLUS “Geo” hinged alloy brake lever
Weight 12.2kg (26.8lbs) not including pegs & brakes/ 122N
Cost £649.99
Front Tire ECLAT “Ridgestone” 2.4″
Rear Tire ECLAT “Ridgestone” 2.3″