Lix BMX

Glossary

…of Old School BMX Parts, Technical Terms, Abbreviations and Slang

(A work in progress, this glossary is a fluid document that is constantly being updated and added to — feel free to contact me if you’d like to see any particular terms included)

#

1/8” chain:
Chain size is specified by pitch and width. The pitch is the distance between rollers (1/2” on all modern bicycle chains). The width is the internal width where the sprocket teeth fit. An 1/8” width chain is used on most single-speed bicycles, including BMX.
1020, hi-ten, high tensile or mild steel:
Hi-tensile steel is a cheaper form of tubing than chromoly steel. It’s not as strong as chromoly so to get the same amount of strength in the bike the tubes must be thicker, meaning a hi-ten bike will be heavier than a chromoly bike. The aesthetic difference between a hi-ten steel frame and a chromoly steel alloy frame is in the quality of the welds. The MIG welds on a Hi-Ten frame are generally chunkier, more irregular with occasional splattering, where as TIG welds form a chain of smooth uniform semicircles, like perfectly repeating waves.
1pc Cranks:
With a one-piece crank and bottom bracket, the spindle and crank arms are a single piece. The bottom bracket shell needs to be large enough to accommodate removal and installation of this S-shaped crank, hence they fit only frames with ‘American’ sized bottom brackets. Bearing cups are pressed into the bottom bracket shell which, in the case of 1pc cranks, most commonly houses loose ball or caged bearing systems which require more maintenance than the sealed bearing systems readily available for 3pc cranks. When installed the 1pc crank holds the cones, facing in; adjustment is made via the left-threaded non-drive side cone. One piece cranks require pedals with 1/2” threaded axels (when installing, remember that left side pedals are reverse threaded).
3/32” chain:
A 3/32” chain is predominantly used on derailleur equipped bicycles that have more than 3 cogs at the rear.
3pc Cranks:
With three-piece cranks the bottom bracket spindle is separate from the crank arms which allows for more strength and rigidity. Three piece cranks require pedals with 9/16” threaded axels (when installing, remember that left side pedals are reverse threaded).
4130, crmo or chromoly steel:
Chromium-molybdenum, a high strength steel alloy which can be made into lightweight tubing with very thin wall gauges, used in manufacturing high quality frames.

A

Aero tubing:
An elliptical tube design used on many higher end chromoly old school race bikes.
Aluminium (or aluminum in the US) frames:
6061 aluminium and 7005 aluminium are the most common aluminiums used for bike frames. Aluminium has a different optimal wall thickness to tubing diameter than steel. It is at its strongest at around 200:1 (diameter:wall thickness). This results in a frame that is significantly stiffer than steel.
Anodised:
Anodising is the electrochemical conversion of the surface of aluminium to an aluminium oxide. This coating is extremely hard (aluminium oxide is used for grinding wheels) and can be coloured by either organic dyes or inorganic metal compounds. Many higher quality vintage racing BMX parts are manufactured from aluminium and anodised for protection and aesthetics. Aluminium parts can be de-anodised using a bath of caustic soda, and re-anodised by professionals.

B

Baseball (re: serial #):
The mark of a quality Japanese frame or part made by Koizumi (ie. early Diamond Back Cobra and Hutch).
Bearing race:
Sometimes referred to as ‘cups’, bearing races are essential components of both the headset and bottom bracket. Each bearing race seats either loose ball or cartridge bearings that allow the cranks and fork steerer to rotate smoothly.
BITD:
Acronym for the phrase ‘back in the day’, commonly used on vintage bike forums.
Boat anchor:
Oldschooler slang for a bike or frame deemed heavy, badly designed, of poor quality, not worth saving.
Bolt Circle Diameter (B.C.D.):
On a crankset, the diameter of the circle formed by the chainring bolts. The most common old school BMX 5 bolt B.C.D.s are 130mm or 110mm diameters.
Bottom bracket:
Connects the crankset to the bicycle and allows the crankset to rotate freely. Contains a spindle that the crankset attaches to, and the bearings that allow the spindle and cranks to rotate.
Bottom Bracket Shell:
A short and wide tube that runs side to side and holds the bottom bracket, connecting the seat tube, down tube and chain stays.
Brake Bridge:
The short length of tubing or plate connecting the seat stays just above the tire. This is the usual mounting point for a rear caliper brake.
Butted tubing:
Among steel frames, using butted tubing reduces weight. The wall thickness changes from thick at the ends (for strength) to thinner in the middle (for lighter weight).

C

Campy:
A nickname for Campagnolo bikes and parts.
Cantilever brake:
A cantilever brake has two separate arms, one on each side of the rim. Each arm pivots on an independent boss attached to the frame or fork, and the two arms are usually coordinated by a transverse cable.
Carpet queen:
Oldschooler slang for a bike built or restored for show only, never to be ridden, often built to factory spec with NOS parts.
Chainring:
A ring shaped sprocket specifically designed to be bolted to a ‘spider’. The benefit over a conventional sprocket is ease of interchangeability for different gear ratios.
Chain stays:
Run parallel to the chain, connecting the bottom bracket shell to the dropouts.
Chain tensioners:
A device used to adjust the chain tension on a BMX by pulling back and locking on the rear axle. Most commonly used on racing BMXs.
Chain tool or chain breaker:
A tool used to press the rivet pin of a chain partway out of a link, in order to disconnect or ‘break’ a chain.
Chequebook collector:
Oldschooler slang for a collector whose goal is to seek out rare, NOS parts or ‘factory’ spec bikes, regardless of price, for show only.
C.N.C.:
Computerized Numerical Control. Refers to modern milling machines that can carve complex parts from solid billets. Without the need for moulds, CNC is advantageous for shorter or one-off product runs.
Crank puller:
The threaded tool required to remove 3pc cranks by separating the drive side crank arm from the spindle.
Chroming or electroplating:
The application of electrolytic cells in which a thin layer of metal is deposited onto an electrically conductive surface. The trick to a perfect chrome finish is in the surface preparation and polishing.
Coaster Brake:
A type of rear hub which incorporates a brake operated by pedaling backward. The most common manufacturers were Suntour, Bendix and Shimano.
Comp III:
Perhaps the most famous BMX tire and tread design. Mitsuboshi developed the Competition III with guidance from Tioga — the first tire designed exclusively for BMX.
Comp IV:
The follow-up to the Comp III, foldable with a more spaced out tread pattern.
Cotterless Cranks:
The modern type of three-piece crankset. The bottom bracket spindle has tapered square ends which fit into matching tapered square holes in the cranks.
Cottered Cranks:
Rarely found on BMX. An old design using wedge-shaped fasteners called “cotters” to hold the cranks onto the bottom bracket axle.
CW style handlebars:
A particular style of BMX handlebar designed by CW, in which the crossbar lies atop handlebars as a continuous piece of tubing extending from grip to grip.

D

Down tube:
Connects the head tube to the bottom bracket shell.
Drilled or undrilled forks:
‘Drilled’ forks have had a hole drilled through the crown for fitting a side pull brake caliper. ‘Undrilled’ forks are often considered desirable collectors items.
Dropouts:
Another name for a fork end — the slot in a bicycle frame or fork where the wheel axle is attached.

F

Fillet brazing:
A classic frame construction where a fillet of brass is brazed onto each joint. A fillet braze frame can achieve more aesthetic unity (smooth curved appearance) than a welded frame.
Floval tubing:
Oversized aluminium tubing with a flattened oval shaped profile. The term ‘floval’ (derived from ‘flat oval’) was coined by S.E. Racing founder Scot Breithaupt for the P.K Ripper race frames designed in 1978/79.
Freestyle standers, extenders, platforms and pegs:
Welded or bolt-on frame or fork modifications that create a foot or hand hold for use in freestyle tricks.

G

Goose:
Abbreviation or nickname for Mongoose bikes and parts.
Gusset:
A metal plate welded to the frame to increase strength in certain areas, most commonly where the top and down tubes meet the head tube.
Gyro system:
The Odyssey Gyro, ACS Rotor or Skyway Spinmaster are all branded design variations of a system that allows the handlebars to spin freely without brake cables becoming tangled.

H

Headset:
The set of components that provides a rotatable interface between the fork and the head tube of the frame.
Head tube or steerer tube:
The short tube at the head of the frame that houses the headset through which the steerer of the fork passes.

K

Kuwi:
A nickname for Kuwahara bikes and parts.

L

Lugged frames:
A classic type of construction for vintage bike frames which uses standard cylindrical steel tubes connected with lugs — fittings made of thicker pieces of steel that are brazed onto each joint.

M

Master link:
A special chain link designed to be easily disassembled and re-assembled.
MIG welds:
Metal inert gas (MIG) welding is a welding process in which an electric arc forms between a consumable wire electrode and the workpiece metal. MIG welds are typically the hallmark of cheaper mild (hi-ten) steel frames.
Monocoque:
Meaning ‘single shell’ in French, a frame design that utilises the external skin to support some or most of the load. The Haro Monocoque pioneered this design in BMX.
Motomag:
An early Mongoose BMX (1975–81) named for its unique 5 spoke webbed design alloy mag wheels.

N

NJS:
Nihon Jitensha Shinkokai — the stamp of the Japanese Bicycling Association, indicating certification as the gold standard in Japanese made parts.
NOS:
Acronym for ‘new old stock’. Applies to parts that have never been fitted, modified, refinished or tampered with.

O

OG:
Abbreviation for ‘original’. (Also ‘original gangsta’ in pop culture.)

P

Potts’ mod:
Invented by Steve Potts in 1984, a hollow-bolt system for the front brakes that enables riders to turn their bars without the front brake cable becoming tangled. The front brake cable is fed from the lever, down through a hollow quill bolt in the stem, out the fork crown, doubling back up the fork leg and into the front caliper from the bottom up.
Powder coating:
A type of frame surface treatment applied as a free-flowing, dry powder. Applied electrostatically and cured under heat to form a hard finish tougher than conventional paint.

Q

Quill stem:
A quill stem requires a set of forks with a threaded steerer tube. The quill stem fits down into the inside of the top of the fork steerer tube, held in place via either a wedge and bolt or cone shaped expander nut. When choosing a quill stem measure the internal diameter of your head tube to determine whether you require a 21.2mm or 22.2mm sized stem.

R

Radial spoking:
The oldest and simplest of spoke patterns. The spokes run straight outward from the hub to the rim.
Rake:
The ‘rake’ or ‘offset’ of a fork is the distance between the wheel axle and the extension of the steering axis. Rake is one of three factors that affect the trail of the bicycle.
Ratchet:
A mechanism which will rotate freely (‘freewheel’) in one direction but will drive another part when turned the other way.
Repop:
Also ‘repro’, a slang abbreviation for the reproduction of an original part that had previously been decommissioned. Can refer to products recommissioned by the original manufacturer, or reproduced by another entity.
Reynolds:
Reynolds (currently TI/Reynolds) is an old and highly regarded maker of bike tubing. Pioneered butted tubing techniques around 1900; its 531 manganese-molybdenum alloy tubing was the standard of excellence for many decades.

S

Seat stays:
Connect the top of the seat tube to the rear fork dropouts.
Seat tube:
Accommodates the seatpost of the bike. Protrudes above the top tube and down to connect with the bottom bracket shell.
Spider:
The multi-armed part of a crank, or crank arm attachment, to which a chainring is attached. 4 and 5 arm configurations are most common.
Sprocket or chainwheel:
A toothed wheel or gear that is part of a chain drive. The use of ‘sprocket’ to refer specifically to a chainwheel is predominantly confined to BMX usage.
Steerer:
The part of the fork that extends upward from the fork crown, into which the handlebars attach via a stem.
Stem:
Sometimes referred to as ‘head stem’ or ‘gooseneck’, the component that connects the handlebars to the steerer tube of the fork.

T

Threadless stem:
Features a modular design that works with threadless forks by clamping around the part of the steerer tube that extends above the headset.
TIG welds:
Tungsten Inert Gas (TIG) welding uses a nonconsumable tungsten electrode to produce the weld, most commonly used in the manufacture of chromoly and aluminium frames. The aesthetically desirable even ‘ladder’ pattern of TIG welds is considered a symbol of quality.
Trail:
The distance from the center of the contact point of the front wheel with the riding surface to the intersection of the steering axis with the surface. Trail has a major effect on the handling of a bicycle.
Trik Topz:
The most famous old school brand name in novelty valve caps. The term is often used to refer to any novelty valve cap, not specifically those made by the Trik Topz brand.
Tri-moly:
A term coined for frames constructed of a chromoly front triangle with hi-ten steel seat stays and chain stays, to make chromoly frames more affordable.
Top tube:
The top tube or cross-bar, connects the top of the head tube to the top of the seat tube.
Tuffs:
Abbreviated term for Skyway Tuff Wheel mags. Sometimes also used generically to refer to any mag style BMX wheel.
Two-pack paint:
Two-Pack Acrylic Enamel, or ‘2K’, is a modern professional paint system. Consists of an acrylic and melamine resin mixed with a poly-isocyanate hardener. A two-pack paint finish is hard wearing and often has a unique depth of colour.

U

U-brake:
A form of cantilever brake that works like a centerpull caliper. The arms cross over above the tire so the left brake shoe is operated by the right side of the transverse cable.

V

V-Brake:
A Shimano trademark for a direct-pull cantilever brake which does not use a separate transverse cable. V-Brakes have more mechanical advantage than other brakes and require special hand levers.

Y

Yoke:
A fitting used on centerpull caliper and cantilever brakes which use a transverse cable, connecting the main cable to the transverse cable. (Often misspelled as ‘yolk’.)

Z

Z-Mags:
A composite 5 spoke mag wheel first manufactured in the early 80s. ACS Z-Mags are injection-molded with glass-filled nylon and are still manufactured today.
Z-Rims:
A composite rim designed by ACS using DuPont’s Zytel material, bridging the gap between light weight racing rims and the strength of freestyle composite mags.