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BMX DICTIONARY FOR BEGINNERS

4130, CHROMO OR CHROMOLY

Refers to 4130 Chromoly, a strong metal alloy used abundantly in the production of BMX bicycles and parts.

20’S:

Twenty-inch bicycle wheels, the most common size wheel for BMX bicycles.

AXLE:

The shaft on which the wheel revolves.

BARS:

An abbreviation of handlebars.

BERM:

A corner on a track built up on the outside of a turn to create a banked curve.

BMX:

Abbreviation for bicycle motocross.

BOTTOM BRACKET:

The mechanism at the bottom of the bicycle frame, which holds the spindle and crank.

BRAKES:

Any bicycle braking system which works by opening and closing two brake shoes on the rim in a clamping motion, like jaws.

BRAKE LEVER:

A lever mounted on the handlebar used for activating the brake.

BUNNYHOP:

Riding along and lifting both wheels off the ground, the starting point for almost all BMX tricks.

CASE:

Coming up short on a jump & the back wheel of the bike hits the peak of the landing.

CHAIN STAY:

 The part of the bicycle frame that runs parallel to the chain.  It connects the bottom bracket to the rear dropouts.

CHAIN WHEEL:

A one-piece front gear.  The chain wheel is attached to the bottom bracket and crank.

CLIPLESS PEDALS:

Hook or “clip” to your clip less shoes.  Some clipless pedals have a cage around the outside of the pedals.

CRANK:

The L-shaped metal arm to which the pedals are attached.

CRUISER:

A Bicycle with 24” wheel diameter.

DEAD SAILOR:

A jump that goes wrong where the rider goes stiff and lands without performing a trick

DOUBLE:

A form of ramp consisting of a separate launch and landing with a gap in between

DOWN TUBE:

Part of the bicycle frame, which slants downward at an angle.  It runs from the head tube to the bottom bracket.

DNS:

Designation on a moto sheet that a rider “Did Not Start” in any particular race.

DRIVETRAIN:

The assembly unit on a bicycle consisting of the chainwheel, chain, and freewheel.

DROPOUTS:

 Small, slotted openings, which hold the front and rear wheel axles.

EXPERT:

Highest level of amateur competition.

FRAME:

The main part of a the bicycle, on which all the smaller parts are attached. Consists of a top tube, down tube, seat stays, chain stays, seat tube, and head tube.

FORK:

The double-pronged section of the frame, which holds the front wheel in place.

FREEWHEEL:

 A one-piece rear gear that allows the rider to back-pedal.  Bearings are built in.

GEAR RATIO:

A number, which indicates the relationship between the two gears and tells you how much work a particular combination of gears will do.

GRIPS:

Rubber or Plastic cover who goes on the handle bars at the end to aid in grip.

HEADSET:

Bearing set for which your front end rotates on and your fork/handle bars slide into.

HEAD TUBE:

A short vertical tube at the very front of the bike.  The front fork fits inside the head tube.