This article covers common terms you'll hear used at BMX tracks, but does not go into the various terms used for the bikes themselves (and the componentry).
BMX, like most other sports, has its own particular language. You'll often hear terms like "getting a good backside", "tap-manual", "rhythm section" being thrown around. Here's what some of those more common terms mean.
When a rider says "I liked that jump on my 20-inch" they are referring to how they liked the jump when using their 20-inch wheeled BMX bike. The two different sized bikes in BMX racing are the 20-inch and the bigger 24-inch wheeled bike, known as the 'Cruiser'. Often riders refer to their two bikes as their "20" and their "cruiser".
In BMX racing, the word "backside" refers to the landing area of a jump, or the downward side of a single bump. When you hear someone talking about "getting a good backside" what they mean is that they made good use of the landing, or downside of the bump, and gained speed on it. Normally a "good backside" involves a bit of "pumping" (see below) to help with gaining speed. See image below.
A berm is a banked corner. Berms can be made entirely of dirt, or covered in asphalt or concrete. A typical BMX track has 3 or 4 berms.
The term 'clips' refers to the use of clip-in pedals. If a rider is said to ride "clips", it means that he or she rides with clip-in pedals. The correct name for clip-in pedals is actually "Clip-less" (just to confuse you somewhat!). Clip-in pedals have been in popular use in BMX since the mid '90s.
The word 'Cruiser' refers to the 24 inch wheel-size BMX bike. It's a bike that is bigger than the standard 20 inch bike, and thus is favoured by older/bigger riders. 20 inch bikes and 24 inch bikes very rarely run in races together - sometimes they do for novelty purposes - but in official competition the two sizes of bike are run in separate races.
The term "double" or "double jump" refers to two bumps on a track that are thought of as being one obstacle. Doubles often give you the option of jumping from the first to the second bump, or manualling/pumping through from the first to the second. (see Manual below). See image below for a typical double jump.
The 'elite' classes of BMX are considered the top classes in BMX racing. Anyone can ride in an elite class if they meet the age requirements, however, the level of skill and speed required is a lot higher, as elite riders often compete on bigger jumps and obstacles than 99% of BMX riders (see 'Pro-section' below).
No rider wants to "flat-land". Flat-landing is what happens when a rider jumps too far on a jump and misses the 'backside' of the jump (the landing area of the jump). It's called "flat-landing" because if you have gone so far that you miss the backside of the jump, you generally miss the downward slope and land on flat ground instead. Flat-landing on a jump is very jarring for a rider and bike and can often result in a crash or a gear breakage (if the jump is a big one). Flat-landing is more of a problem on big jumps, where the consequences of getting it wrong can be painful, than it is on small jumps. On smaller jumps a rider can absorb the energy involved and carry on.
Gate / Gates
The word 'gate' is used as a shortened method of referring to the start gate (see below). The terms 'gates' is used to describe the process of doing one or more gate starts. Riders will often say "my gates haven't been good today". What they mean is that they have not been starting well in their races. When a rider says "I'm going to go and do some gates" they mean they that are going to go and practice their gate starts.
Gear-inches is the unit we measure our BMX gearing (front and rear cogs) with. You'll hear numbers like 52,53.6 etc. Those numbers represent a distance measurement that helps BMX racer's decide on what gearing to run at a given track. Don't mistake that for the distance you travel in one pedal revolution though, as that's not what that number actually represents.
When a rider 'gets a holeshot' it means that he or she is the first to leave the start gate and get a lead on the rest of his/her competitors. It doesn't necessarily mean that the rider will be leading into the first corner - but they often do. Basically, the term holeshot is used to refer to who gets the best start in a race.
The term 'lip' refers to the 'sharpness' of the top of a jump. If a jump has a sharp lip, it does not gradually curve from its up-face, to the top surface of the jump. Think of the lip of a jump is like the base of a ski-jump where it kicks upward to help the skier fly through the air. Sometimes BMX jumps contain a very steep section right at the tip of the jump to help riders reach the height they need to jump the obstacle. If you are not a jumper, obstacles with lips can be difficult to ride as they are designed to help you lift off the ground. Staying on the ground on 'lippy' jumps can be tricky to achieve if you ride them at speed.
The term "manual" refers to riding along on your bike on the rear wheel only (without pedalling). Think of it as pulling a 'wheelie' without pedalling. In racing terms, this technique is normally used to gain speed through smaller rhythm sections or "doubles" and is not something that is done over a long distance - it's normally used only momentarily - to gain speed. The technique is widely used in freestyle/skatepark riding - where manuals are often performed over very long distances.
When a rider "over-jumps" an obstacle, what that means is that he or she has jumped too far and missed the 'backside' of the jump. Sometimes an over jump can be only a matter of inches - sometimes you can miss the entire backside and have what we call a "flat-land" (see above)
The term 'pre-lift' refers to a technique used by some riders whereby they lift the front wheel of their bike up onto an obstacle rather than ride up it in a normal manner. Pre-lifting enables the rider to gain more speed as they crest the top of an obstacle. A pre-lift normally goes hand-in-hand with a 'pump'. In other words, a rider will pre-lift up onto an obstacle, then pump off the back-side of the obstacle in one fluid movement. When done correctly, this technique provides a good boost in speed.
A pro-section is an alternative section of a BMX track that is dedicated to 'elite' riders. It normally contains very big jumps and/or very challenging rhythm sections. Pro-sections are not ridden by 99% of BMX riders as they are considered too difficult or dangerous for the average rider. As part of a competition, elite riders must ride pro-sections unless conditions or other circumstances dictate otherwise (strong winds can be a problem at times as can wet weather). The most extreme pro-sections can involve jumping from the inside to the outside of one of the corners on the track (essentially jumping the entire width of the 'non-elite' track).
The term "pumping" refers to a technique used in racing to gain speed over bumps and jumps. When you "pump" a rhythm section, you use your arms/legs and bodyweight to gain speed by moving in a rhythmic manner while you ride up and down the bumps. Simply put, when you're going downward, you push the bike 'down' into the ground - when you're going up, you maximise your body position to be able to push down really hard when you start going down. It's a little hard to explain, but we'll hopefully have some videos on the matter soon.
A rhythm section on a BMX track is a part of the track consisting of several bumps and obstacles placed together in a tight grouping. The 'rhythm' part of this term comes from the belief that a rider can get into a 'rhythm' through those obstacles to gain or maintain speed - normally by pumping and/or manualling. Normally one full straight of a track is dedicated to a rhythm section. Often (but not always) the rhythm section of a track is the last straight before the finish line.
The term "roller" refers to a single bump that is not too steep or sharp and can be ridden over at speed without being flung into the air too aggressively. Roller style bumps don't tend to have 'lips' on them (see 'lip' above).
Spin / Spinning
The term 'spin' refers to pedalling fast. There is an old saying in BMX racing, "spinners are winners", meaning that if you have the ability to pedal at a fast rate, you may be more likely to win a race. Often riders will set the gear ratios of their bikes to ensure that they pedal at their most comfortable 'spin' rate.
The start gate is the barrier that riders must be placed behind at the start of a race. It is placed at the top of the start ramp and controls the start of a race by dropping or pivoting down out of the riders way. Riders generally balance against the gate in order to maximise their performance at the start of a race. Riders' front wheels must be touching the start gate as the start sequence of a race begins.
Start Ramp /
The start ramp is the hill that a BMX race starts from. They can range from relatively small, to massive and steep. Most start ramps allow for 8 riders to start a race at once, although some older tracks have space for six riders only.
A step down is an obstacle where the landing area or 'backside' is lower than the 'up-face' or 'take off' area of the jump. When you jump a step-down, you land at a lower point than where you lifted off the ground. This is the opposite of a 'step-up' (see below).
A 'step-up' is an obstacle where the 'landing' area is set higher off the ground than the 'take off' area. In other words, if you jump a step-up obstacle, you will be landing your jump at a point that is higher than where you lifted off the ground. This is the opposite of a 'step-down' (see above). Both step-up and step-down names can be used in combination with other obstacle names. For instance a jump that 'steps up' and contains two bumps on the top instead of one is referred to as a "step-up double". A step-up can be thought of as a table-top jump with a higher bump on the landing area.
A 'table-top' is a jump that consists of an 'up-face', a flat and level top, then a 'backside'. Table-top jumps can be very long on some tracks. Waitakere's first jump is a table-top that is 5 metres long.
A 'tap-manual' is a manual that is used to position the bike to maximise the approaching back-side of an obstacle. Tap-manuals are often performed over table-top jumps to aid the rider in getting as much of a gain off the backside of the table top as possible. Essentially it's a momentum-gaining movement that maximises the potential energy of the bike and rider - in the hopes that the energy will result in "getting a good backside" on the table top (or other obstacle). They can be used elsewhere - like shallow rythm sections - but you'll mostly see them on table-tops. They are referred to as 'tap-manuals' as the rider almost just 'taps' the surface of the track with his or her back-wheel.
The term "transition" refers to the area of a jump where the rider goes from being on flat ground, to moving onto the "up face" of the jump. Essentially, it's the curved area at the base of a jump that you ride up on to. Riders may refer sometimes to "pumping the transition" to gain speed as they head up a jump.
Like a 'double', a triple is often thought of as one obstacle. The difference being that a triple has three bumps instead of two. The same theories apply as the double, sometimes riders will jump from the first bump to the third, some will "pump" or "manual" through the bumps instead. Others will jump from the first to the second, then pump through the third. There are many possible ways to ride a triple - it often comes down to rider ability or race situation (for instance, sometimes you may not have room during a race to attempt to jump the entire obstacle in one go).
The 'up-face' of a jump is the front side of the jump that the rider rides up to ride over the obstacle. Consider it the 'up hill' part of the jump. The 'down hill' part of the jump is known as the 'backside'.
When a rider says that they "un-clipped", what they are referring to is one of their feet coming loose from their clip-in pedals (incidentally, and confusingly, the proper term for those clip-in pedals is actually "Clip-less"). Riders most often come un-clipped at the start of a race, but it can happen at any time on the track. Normally when a rider un-clips, it means the end of their chances in a race, as it often takes too much time to re-clip the un-clipped foot back into the pedal.
This is a term that used to be more common but is not really used much any more. It originally came from Moto-X. A 'whoops' section is essentially another term given to a 'rhythm section' (see above). In the 'old' days of BMX, what we now call 'triples' (see above) were sometimes referred to as 'whoops'.