Things you might hear in BMX:
BIKES
Class: Rolling on 20-inch wheel bikes (the rim is actually 16" but with tire it is 20")
Cruiser: Cruising on 24-inch wheel bikes (the rim is actually 20" but with tire it is 24")
Clips: Anything that mechanically secures your foot to the pedal. Clips 99.99% of the time refers to clipless pedals. Did anyone ever try toe cages in BMX?
Flats: A pedal with a flat surface and no mechanical attachment to your shoe.
Gearing: This means to the front and rear gears. If the front is 44 teeth and the rear is 16 it is 44/16.
Gear Ratio: Divide the two numbers above and get a ratio. This ratio is good for a quick starting point for tuning your gearing. For teen and adult riders the starting point is 2.75 (44/16=2.75) and for kids about 2.6.
Gear inches, gain ratio, rollout: These are calculated numbers based on gearing, crank length, and tire diameter. They are more accurate for fine tuning.
TECHNIQUES
Spin: Fast cadence.
Mash: Slow cadence.
Think of spinning as a V-12 at 8,000 RPM. Think of mashing as a diesel at 2,000 RPM. Both create power just in different ways.
Manual: Everyone has definitions for what is and isn't a manual. Basically, as a rider is going down fast down a backside they push the rear wheel down while holding the front wheel up. It is most often done in rhythm sections. Manuals work best when they flow out naturally. Manualing in BMX is one wheel pumping.
Pumping: Pumping is used to maintain or gain speed over bumps and humps. It makes an up-down-up-down rhythm where you are pushing your bike down and up across rollers. Both wheels stay on the ground.
Case: Coming up short on a jump. Most of the time casing ends in crashing.
Snap: A way to launch off the gate to give a rider a little more oommpphh and shaving a little time off the start. It is a learned skill that may take a while to pick up.
AT THE TRACK
Moto: The race part. In most races there are three motos per rider group. In UCI races motos are also called ‘heats.’
Obstacle: Anything not flat on the track.
Backside: The down side of an obstacle.
Face: The up side of an obstacle.
Turn: A turn is a banked corner, sometimes called a berm. They are made of dirt or asphalt. Most BMX tracks have 3 turns. Some have 4.
Double: Two bumps on one obstacle.
Triple: Three bumps on one obstacle.
Gate: Literally a hinged gate. It’s at the starting hill. The gate is where the race starts. There are a few styles of gates, but they all fall forward.
Starting Hill,The Hill: The place where you start. Can’t miss it.
Staging: The area on or near the hill where riders are organized into their motos before loading in the gate.
Holeshot, taking the holeshot: The rider that leads the others down the first straight "took the holeshot." In pro level racing taking the holeshot often means winning the race. In amateur racing taking the holeshot doesn't always mean winning the race.
Pro-section: A big jump. Pro-sections are basically two ramps; jump off one, land on the other. In between the jumps there are crocodiles, piranhas, and cobras.
Rhythm Section: A rhythm section is several rolling bumps (rollers) placed together in a grouping. The rhythm part comes from the up-down-up-down rhythm of pumping.
Roller: A single low rounded bump.
Step-down: A step down is like going down the stairs.
Step-up: A step up is like going up the stairs.
Tabletop: A tabletop is like a butte in geography. They are great to learn jumping skills on. Everyone likes tables.
Pits: The area around the track where you can find food vendors and have your non-race space. Also, it is where hordes of semi-feral kids rove.