Pedal Pusher Bike Shop, New York, NY
1306 Second Avenue New York, NY 10065
Nearest subway: Q to 72nd St(new 2nd Av subway!) or #6 train to E68th St Hunter College

Open till 6pm, Thursdays to 8pm

Tel 212-288-5592  |  Out of town call toll free 800-300-3023



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Cycling Glossary

Alphabetical, of course

Acera: Shimano's model of mid- to low-level recreational mountain bike componentry.  It works okay.

acorn nut: A nut with a conical shape over one side.  It may be decorative, as on the pivot bolt of a side-pull brake, or it may be protective to prevent scrapes when your skin brushes against it.

adjusting barrel: This hollow device allows fine adjustment of the brake or gear cable which runs through it.  When turned by the fingers, it pushes the cable "housing", effectively making the cable inside tighter or looser.  Adjusting barrels compensate for wear on brake shoes, re-adjust derailleurs, and generally make life easier for the mechanic. 

adjustable cup: The "cup" of a ball bearing system is the shell outside the ring of ball bearings, and which they press against.  Inside the ring of ball bearings, the balls run against a "cone".  When such a system allows adjustment of the pressure on the ball bearings by turning the cup, voilà, an adjustable cup.  Bottom brackets which contain two cup-and-cone systems (one on each side of the bottom bracket) will usually have an adjustable cup on the left, and a fixed cup on the right.

aerobars: Also called "time-trial bars," these are handlebars or handlebar extensions designed to allow the rider to lean forward more and hold his arms closer together, thereby presenting a smaller area to wind resistance.  Bikes with aerobars are difficult to maneuver and not more comfortable.  Brake and gear levers are often less convenient, and these bars are prohibited in bike races, except for time-trials.  One source I consulted attributes the aerobar's acceptance to Pete Penseyres and Greg LeMond.  There are many variations in size, shape, and method of attachment, as well as innovative brake and gear lever adapters.
aero brake levers: Brake levers on racing bikes with the brake cables routed through the handlebars or underneath the handlebar tape.
agrupado: (Spanish) peloton, or group of riders. 
aheadset: a threadless headset.  Originally the proprietary name for Dia Compe brand, the term aheadset is now generic, like scotch tape.  In addition to the difference from the threaded headset itself, the aheadset handlebar stem clamps around the outside of the fork steerer tube instead of extending inside it.  The whole system is easier for mechanics and is stronger and more reliable. The alternative to aheadset is the "threaded headset" and "quill stem."  Most aheadset systems are 1and 1/8 inches measuring the outside diameter of the fork steerer tube, although other standards do exist.

airless tires: Solid, non-pneumatic tires that don't take air.  Found on baby carriages, wheel barrows, and occasionally on bicycle products, the ride is harsh and unreliable under adverse conditions.  Since invented by the Scottish cyclist Dunlop, the pneumatic tire, filled with air, has almost completely taken over.  See patch-kit.

Alivio: the name Shimano brand gives to economy priced, entry-level equipment.

Allen rack:  The R. A. Allen company has been manufacturing car racks for many years.  They are reliable, inexpensive, and easy to install.  The least expensive rack fits the back of almost every car ever made.  You hook some straps to the edge of the trunk or rear door and you're done!  There are many variations, and you may see one in our catalogue, if you click here.

Allen wrench (also Allen key):  A tool with six sides designed to fit into a six-sided opening at the head of a bolt, enabling the user to get a good grip on the bolt and to maneuver in inaccessible areas.  Furthermore, the tool is lighter in weight than other wrenches and more compact, so Allen wrenches are more convenient to take along on a bicycle.

all-rounder: The shape of handlebars sometimes found on cruiser bikes, with a slight rise and bending toward the rear of the bicycle to an ergonomic hand position, almost parallel to the centerline of the bicycle.  This shape is great for cruisers, but is not for agressive or fast riding, nor is this shape safe for adverse conditions.

Alpine gearing: Gearing set up for steep hills.  It may be a triple crankset with very low gears and then evenly spaced gears gradually reaching high (or fast) gears. Or it may be a setup using middle and high gears, with one or two very low gears added on for the steepest hills.

aluminum: One of the natural elements, a metal which is often used for bicycle parts.  Aluminum is cheap and abundant and doesn't rust, but its pure form is not very strong and not useful for bicycle products.  When combined with other elements, such as silicon, magnesium, zirconium, etc., and when heat-treated, it becomes much harder, stronger, and less brittle. Aluminum requires an atmosphere of argon or other inert gas in which to be welded. 
     Many quality bicycle parts such as brake calipers, chainwheels, rims, and cranks are almost always made of aluminum.  Other parts, such as the surfaces ball bearings run against, the ball bearings themselves, chains, and other extremely high stress and pressure items are never made of aluminum.  And some parts, such as handlebar stems can be successfully made of aluminum, steel, titanium, and other materials. 

Americaine: (French, "American") See "Madison."

anchor bolt: A bolt designed to clamp a cable (not a bolt on a ship's anchor.)  Be careful tightening an anchor bolt.  Some are designed with a hole for the cable to penetrate and then a nut pinches the cable tight.  Other anchor bolts have a special washer that will capture the cable.  Some of these washers are deceptive: the hook that appears to be designed to capture the cable is actually a tab to keep the washer from turning as it tightens down.  Also it may be critical for the cable to pass along the proper side of the bolt.

angles: Remember your tenth grade geometry?  The angles between the tubes of the bicycle frame help to determine the characteristics of the ride.

ankling: Use of the ankles while pedaling, such as pointing the toes down during the down stroke and up during the up stroke.  One source I consulted warns against this practice as destructive to the achilles tendons.  Be forewarned.

anodize: to electroplate, usually an aluminum surface.  The process may make the surface harder and often a darker color.  Sometimes the anodizing process also makes the material brittle. 

ANSI: American National Standards Institute, an organization which establishes objective standards for consumer products.  The standard ANSI Z90.4 is one of the accepted standards for protection of bicycle helmets.

arc-en-ciel: (French "rainbow") The multi-colored stripes on a world-champion jersey.

arch: on a front shock absorbing fork, the curved connector that supports both legs of the fork.  This arch may also have fittings for a brake cable, reflector bracket, etc.  Arch is a common misnomer for the brake calipers that hold the brake pads against the rim when stopping.

arcobaleno: (Italian "rainbow") The multi-colored stripes on a world-champion jersey.

arrêté: [French, "stopped"] standing start, in track racing. A track stand.  

arrivée: [French] finish line.

Ashtabula crank: A one-piece crank.  This obsolete name refers to the city in Ohio where they were originally made.  See "crank, one-piece".

atb: What we used to call an "all terrain bicycle" is now generally called a "mountain bike."  (In France, it is still called un vélo à tout terrain, or vélo a-t-t.)

attack: In a race, when a rider accelerates to pass another cyclist or to move ahead of the pack.

Audax: A kind of club ride where participants keep a pace-line, but do not rotate to the head of the line.  Riders may have to stop at check-points.

autobus: [French] A slower group far behind on a mountain.  Although they finish within the time limit, these riders are sometimes derided (pun intended.)   Also "grupetto" and "laughing group."  Maybe they are so slow, they should take a bus, but they are stronger riders than I am.

Avocet: An American brand of tires, saddles, cyclocomputers, and other products.  (Pronounced "Av-o-sett.")
axle: The interior shaft of a hub or bottom bracket.
axle set: an axle along with the cones, nuts and washers.  Sometimes includes the bearings, and/or dust covers.  Usually an axle set means the interior parts of a hub, not including any gear parts, but I have heard the term "bottom bracket axle set" as well, which would include the cups and bearings, as well as the spindle of the bottom bracket.

azzurri, squadra azzurra: [Italian] blue team; the colors of the Italian national team.

B-Tension Adjuster: On a Shimano rear derailleur, there may be a screw to adjust the limit of rotation of the derailleur body, as it shifts the chain from one gear to another.  Spring tension of the pulley wheels tends to "wind up" the derailleur and take up slackness in the chain.  The more chain that wraps around the cog set, the better shifting and less wear.  As this adjustment brings the derailleur closer to the cog set, be careful not to let the pulley wheel scrape in any of the gears.

balai: [French] last support vehicle in a race.

balance: Ironic name for the high-wheel bicycle, that was difficult to balance.

baroudeur: a cyclist who excels on long flat terrain.  Also "rouleur." 

ball bearing:  A spherical steel ball that runs between two metal surfaces, reducing friction to nearly zero.  The space between the ball bearing and the surfaces it contacts must be carefully adjusted.  If the pressure on the balls is too loose, then they wander around, they crash into each other and the running surfaces, they wear out very quickly, and they may create serious symptoms for the bicycle.  If they are too tight, they won't turn smoothly and will scrape away the running surfaces.  Ball bearings must be lubricated.  Sometimes, a set of ball bearings is held together in a clip, which keeps the bearings equidistant during use, or in a sealed cartridge.  Loose bearings, without a clip, will permit a greater number of bearings to be placed in the system, thus spreading the pressure and wear among more bearings.  The quality of the metal is important in ball bearings, but they are rarely labeled as such.  Sometimes the label may specify "grade 25", which means that the bearings are made to conform within 25 thousandths of an inch.  Campagnolo brand recommends never mixing bearings from different manufacturing lots, because of differing tolerances.  Ball bearings are always measured in fractions of an inch, and never in millimeters, although I don't know why.

balloon tire: A wide tire, usually rated at low pressure, often found on cruiser bikes.

banana seat::   A long narrow seat popular on kiddie bikes in the eighties.  Often decorated with graphics.  Not very useful on adult bikes.

bar: Short for "handlebar". Also in physics the unit of air pressure equal to atmospheric pressure, 14.5 psi.  Occasionally, you may see a tire labeled, for instance, "Maximum pressure 4 bar."  Multiply 4 x 14.5= 58 psi (pounds per square inch.)

bar ends: Little extensions on the end of handlebars, giving you alternate positions for your hands.  Also called "hill-climbing bars."   Some people call bar ends the gearlevers attached to the ends of the handlebars.

barcons:  derailleur gearlevers mounted on the ends of the handlebars, usually by an expander bolt inside the bars.  Also known as "goody shifters." 

basket: container for carrying things.  Please, NOT toeclips.

Bassworm: brand name of a little gadget that contains a spring to help take up slack in a rear derailleur cable as you shift.

B.C.D.:  Bolt circle diameter.
Bead: A stiff metal wire within the casing of a tire that helps to position the tire on the rim.  If made of kevlar, then you may be able to fold the tire compactly.

bearing: the surface where two parts press or move against one another.  Typically, a spherical or cylindrical bearing will roll along another bearing surface, flat or curved, reducing friction to nearly zero. See "ball bearing" and "cartridge bearing". 

beater: a bicycle that can take a beating, one often used for everyday errands and locked outside in the weather.

bell crank: the pivoting lever device on a Shimano three-speed hub that converts the pull of the cable into pressure on the push rod that changes gears.

bidon: water bottle (French, n.m.)

billet: a piece of metal as it comes from the foundry, before it is shaped and manufactured into bicycle parts.

binder bolt: a bolt which squeezes a clamp tight, for instance to secure the seatpost or handlebars.

Biopace: Shimano's term for oval-shaped chainrings, designed to give more power around the entire 360 degree range of the cranks.  When the cranks are vertical, the rider has less leverage, so the chainring compensates. Biopace chainrings were marketed in the 80's.

blade: one leg of a front fork.  Also when spokes are flattened so they cut aerodynamically through the wind as they rotate, they are called "bladed." Bladed spokes must be oriented correctly in order to work right.

BMX: Short for "bicycle moto cross," a kind of race on a dirt track which appeals to kids with jumps and other hazards, sort of a snowboard terrain park for bikes. 

bolt circle diameter (b.c.d.): The diameter of the imaginary circle formed by the chainwheel bolts on a crankset.  It is difficult to measure, because odd numbers of bolts do not line up on a diameter, and the crank is often in the way.  You can, however, measure the distance between two adjacent bolts and calculate the BCD.  According to Sutherland's Handbook, for three-bolt pattern, multiply the adjacent bolt distance by 1.15 to get the BCD.  A four-bolt pattern, multiply by  1.4.  Five-bolt pattern, multiply by 1.7.  And six-bolt, multiply by 2.

boom tube: the large frame tube at the bottom of a tandem.

booster: a metal arch that supports and stiffens the mountings of cantilever or linear pull brakes, enhancing performance.  Also a short tube extending the mounting height of a handlebar stem, raising the handlebars several inches.

boot: a jury-rigged temporary patch on the inside of a damaged tire, preventing the inner tube from bulging through the opening.  A boot can be improvised from anything handy, such as a dollar bill, food wrapper, or an old piece of tire.

boss: a small fitting welded onto the bicycle frame usually for mounting something securely, such as a water bottle, or the brake arms.

bottom bracket:  the part of the bicycle frame designed to hold the bearings that allow the cranks to rotate.   Also the bearing set that fits there.  At first, with one-piece forged cranks, the bottom bracket was rather crude.  Then the three-piece crank evolved requiring a high-precision bottom bracket, including carefully machined threads on both sides of the frame and a smooth face to mate with the edges of the cups that screwed in.  The balls and other parts required careful assembly and adjustment.  Since the 90's, most bottom brackets come pre-assembled in a sealed cartridge that costs a little more than the previous system, but is much easier to install and saves on maintenance.  Cartridges are often interchangeable with the prior system, if you get the right size.

bottom bracket drop: The vertical distance between a line drawn between the center of the two wheel axles and a parallel horizontal line through the bottom bracket.  The larger the bottom bracket drop, the lower is the bottom bracket, and the lower is the bike's center of gravity.

bottom bracket height: The vertical distance from the ground to the center of the bottom bracket.  Mountain bikes need high clearance over obstacles.

bottom pull: a front derailleur with a cable that pulls from the bottom.

brake: a device for slowing a bicycle, activated by hand or foot.  Many variations exist.

brake bridge: a tube or rod that connects the two seat stays and on which a rear brake may be mounted.

braze-on: a fitting welded (brazed) onto a bicycle frame, usually designed for a specific purpose, such as carrying a pump, mounting a luggage carrier, holding the chain when the rear wheel is removed, mounting the gear levers, or for other utilities.

brazing: a kind of welding using a molten metal which melts at a lower temperature than the parts being welded.  Soldering is another method where the liquid metal melts at even lower temperatures.  See also "welding," and "fillet brazing."

breaker bar: an extension handle (or longer handle) on a wrench enabling the user to "break free" a bolt that is stuck.

brevet: a race or other event which qualifies the rider to enter another.

brifter: a brake lever combined with a gear shifter.  Not in common usage.

Brinnelled: a condition which arises when ball bearings dent the surface on which they run.  Typically, a headset becomes Brinnelled when poorly adjusted, not lubricated, and/or subjected to extreme or prolonged stress in the straight-ahead position on a bike.  Brinnelled headsets feel like hills and valleys as you turn the handlebars and if you lift the front wheel off the ground, the handlebars tend to "center" themselves in the straight-ahead positon.  Occasionally, Brinnelled headsets can be adjusted for a temporary extension of use, but plan to replace the headset and service it more often.  Named after the Swedish engineer Johan Brinnell.

British: the system of measurements and engineering decisions common in Britain during the development of the modern bicycle, many of which have defaulted to most of the bicycle industry.  For examples, spoke threads are 56 threads per inch, bottom brackets are 1.375" x 24 tpi with a left-hand thread on the fixed cup, and all ball bearings are measured in fractions of an inch.  Thankfully, the British and Whitworth thread systems of nuts and bolts have fallen out of favor, replaced by metric.  According to Sutherlands, the profile of threads on a British bolt is cut differently from Japanese, French and Italian standards, but it is close enough to make a good fit anyway, if the number of threads is correct.

Brodie: a show-off turn of 180 degrees, executed by locking the rear brakes and skidding.

B.S.C.: British Standard Cycle.  The system of dimensions and engineering decisions used on British bikes that came to represent the standard of the entire bicycle industry in many parts of the bike.

bunji: an elastic cord that stretches to hold packages on your bike luggage carrier.  Bunjis of different lengths are also useful for holding bikes onto a car-rack, holding luggage when you wheel it through an airport, etc.  BE CAREFUL that the metal hook doesn't snap back and injure you.

bushing: a hollow cylinder used to adapt round objects of different sizes, or to act as a bearing. 

butted: When the metal wall of a bicycle frame is thicker at the end than in the middle, we say it is "butted".  See "double-butted."  Other parts of the bike, including the fork, can be made of butted tubing.

cable: thin piece(s) of wire, usually twisted together, which transmit pulling tension from controls to brakes or gears.  Ordinarily, all or part of the cable is covered by "housing", which compresses when tension is applied to the inner cable. Occasionally, cables are used for other purposes, too, besides brakes and gears.

cable carrier: A hook-like device which, when attached to the end of a brake cable, hooks and pulls another cable, usually cross-wise to the first.  Also called a "yoke."

cable guide: a curved metal or plastic contrivance, which allows a brake or gear cable to change direction, or which enables the mechanic to insert a new cable more easily, such as hidden within the tubes of a bike frame.  Cable guides may be welded onto or within the frame or may be bolted on.

cable stop: a gadget that stops the outer housing from passing, but allows the inner cable to move within, transmitting tension.  Sometimes a cable stop is welded onto the frame, sometimes it is clamped on with a bolt, and sometimes it is part of a brake or derailleur, with or without an adjusting barrel. 

cadence: number of revolutions the pedals turn per minute.  A cadence of 60 rpm, is typical for efficient riding.  If you are pedaling slower than this, switch to a lower gear, so you can increase your cadence.  Many riders don't feel they are getting a "workout" if they don't feel their muscles pushing great forces.  This is not correct.  Pedaling in high gears at slow cadence will destroy your knees, and you will run out of power much sooner.  It is very exciting to watch a racer suddenly accelerate and pedal at 120 rpms or higher.

cage: 1. a waterbottle holder. 2. the part of the front derailleur which surrounds the chain and moves it sideways from one chainring to another.  3. a metal or plastic clip which holds ball bearings, making life easier for the mechanic and keeping the balls separated while in use (also called retainer.) 4. on a pedal, the structure that attaches to the spindle and on which the foot rests.   

calipers: a device with two arms, articulated or hinged together.  1. Measuring calipers are adjusted to the size of the object being measured and then either show the dimensions on a scale or dial, or can be placed against a measuring scale of known dimension. 2. the parts of a side-pull brake that pivot together to press the brake shoe against the rim.  Cantilever brakes and linear pull brakes (V-brakes) have arms which are not hinged directly together, but are sometimes incorrectly called calipers, too.

cam: a bump on a round surface, which pushes against another surface as the bump passes by, thereby making the other surface move away.  The purpose may be to increase mechanical advantage creating great force, or the purpose may be to convert rotational motion into linear motion. The most common cam on a bicycle is in the "quick-release lever" of hub skewers. (There may be a better engineering definition, but this is a pretty good working definition.)

Campagnolo:  A well-known and well-respected Italian manufacturer of bicycle parts.  Tullio Campagnolo was a racer who had trouble removing a wheel one day, and invented the "quick release" axle, which remains in use on almost every bicycle today.  "Campy" (in the UK, they say "Campag") was the main supplier to the professional racer until about 1988, when other brands began to make first-quality race componentry, too.  Please note that Campagnolo does NOT make bicycles (that is, bike frames), saddles, handlebars, and other necessary components for a bicycle.

cantilever brake: a cantilever is a long lever arm that sticks out, giving great leverage or balancing a large load.  Cantilever brakes have two separate long arms that stick out on either side of the bicycle rim.  When pulled by a cable, the long arms pivot inward and press the rubber brake pads against the rim, with great pressure.  The advantage of cantilever brakes is that you can apply strong braking power at the same time as leaving lots of space around the wheel for fenders, racks, and other accessories.  The disadvantage is that they are tricky to adjust, and sometimes during a cable failure, the spring behind the cantilevered arm may rotate the arm backwards all the way around into the spokes, a very bad thing. 

cantilever frame: a cantilever is a long lever arm that sticks out, giving great leverage or balancing a large load.  I'm not sure what relavance this has to a cruiser frame, but we call a frame with long curving tubes starting at the rear dropouts and continuing past the seattube all the way to the headtube, a cantilever frame.

captain: the front rider on a tandem.  (The back rider is called the stoker.)

carbon fiber: a filament or long strand of carbon with great tensile strength, but zero compression or bending (torsional) strength.  When these filaments are woven or arrayed within a plastic resin, the resulting material has strength in tension and compression and torsion.  In fact, clever engineers can orient layers of carbon strands in several directions creating amazing strength in multiple dimensions simultaneously.  A bicycle frame has different stresses in different areas, and carbon fiber can be designed to give great strength at minimum weight.  But the carbon fiber and the resin must be made in a mold which itself is very expensive, so the cost must pass on the retail price, expensive.  Recently, carbon fiber forks have become standard on good racing bikes.

carcass: the canvas backing of a tire.

cartridge bearings: a set of bearings, pre-assembled as a unit.  It is easier to install, but they are rarely adjustable or serviceable, so you just replace the whole cartridge when needed.  Often, there is a seal to keep dirt out.  Most common is the bottom bracket.

cassette: the set of cogs at the rear hub assembled as a unit without a freewheeling mechanism.  The cassette fits onto a freewheeling mechanism which is part of the hub; the cassette (and the chain) can be held still while the wheel turns, allowing for "coasting".  (The other common system of cogs, assembled as a unit does contain a mechanism to allow the wheel to spin, and this other system is called a "freewheel," q.v.  In this case, there is no freewheeling mechanism in the hub.)  The advantage of a cassette system is that the cassette can be changed (and cleaned) more easily, and it can usually be made lighter in weight. Furthermore, the axle bearings and the spoke holes can be spaced wider creating a stronger system.

casting: a method of forming bicycle parts by filling a mold with molten metal.  Some molds are re-usable, and some are disposed after each use.  Investment casting ("lost wax method") is an expensive process where a wax model is made and a plaster cast is shaped around the wax.  Then the wax is melted out and the paster is filled with the metal, which then cools into the original shape of the wax.  High quality steel racing bikes used to have lugs, bottom bracket shell, and fork crown made this way.  Now other manufacturing methods have taken over.

center pull brake: a brake system where the cable pulls from the middle, attached to the brake by means of a hook (sometimes called a yoke or triangle bolt) which pulls against a transverse cable attached to the two arms of the brake.  By adjusting the tension of the transverse cable, you can alter the brake power and the distance the brake pads move (inversely).  Another advantage of center pull brakes is that you can have lots and lots of room to mount fenders and other accessories.  We see centerpull brakes on cyclo-cross bikes these days, because the extra room allows mud and debris to pass through.  Shimano produced a kind of center pull brake without a true transverse cable; the main long cable had to feed through a clamp before it attached directly to one arm of the brake.  The clamp was attached to a short cable that ran to the other arm.  The idea was to make sure that the tension (length) of the transverse cable was always the same.
center to center: the measurement from the center of the bottom bracket to the center of the top tube along the seat tube.  This is a more consistent comparison than center to top from one brand to the next, but it is not perfect, either, since tubing comes in many sizes and many frames have a "compact" design with only virtual measurements.
center to top: the measurement from the center of the bottom bracket to the top of the seat tube.    (Pinarello bikes had a little point on the seat collar and he measured to the top of the point.)  Since often the seat tube extends some distance over the top tube, the center to top measurement is an inconsistent comparison from one bike to the next.
century: a 100 mile bike-ride or race.  A "metric century" is 100 kilometers (62 miles.)

chain: the system of metal links that transfers power from the front chainwheel to the rear wheel sprockets.  Modern bikes have approximately 114 links (or 57 pairs of links).  Each pair of links consists of two outer side plates, two inner side plates, two rollers, and two rivets. 8 times 57 equals 456 parts on every chain!  The roller sits on an interior protrusion of the inner side plate.  Older chains have instead a bushing for the roller to ride on; modern chains are "bushingless."

chainring: the toothed gear attached to the crank, which powers the chain.  A normal chainring may have anywhere from 20 to 54 teeth; the bigger the chainring, the "higher" the gear or the harder it is to turn the pedals.  Many bikes have two or three chainrings bolted together so you can select a higher or lower gear while pedaling.  (Specialty bikes may have chainrings with any number of teeth, greater or lesser than normal chainrings.)

chainstay: the part of the bicycle frame connecting the bottom bracket to the rear dropout.  The right chainstay is next to the chain; the left chainstay is on the other side of the bike, but still called a chainstay.  Chainstays are generally measured from the center of the rear axle to the center of the bottom bracket.

chain wear or chain stretch:  Chains don't stretch.  They do become elongated because of wear.  Consider that if each roller wears only 1/100 of an inch, then the total wear over 114 links is more than an inch!  The measurement of length between each link of a modern chain should be 1/2 inch, which can be measured easily with a ruler (line up the center of each rivet; measure across twenty-four links, twelve inches.)  If the measurement is more than 1/16 inch too long, over 12 inches, then replace the chain.  If the measurement is more than 1/8 inch too long, then replace the chain and freewheel or cassette as well.  A recreational chain kept clean and lubricated, may last 1500 to 3000 miles.  Racing chains, used under severe conditions and made of weight-saving materials, may last only 500 to 1000 miles.   

chainwheel: Another name for a chainring.

chrome-molly: An alloy of steel containing chrome and molybdenum.  Chrome-molly alloys are stronger than "hi-tensile" steel, and therefore the bicycle needs less of it to achieve a sturdy frame.  See also "4130".
clipless pedals: A pedal which holds onto your shoe without the use of toeclips.  Originally, pedals were easy to describe, just a platform of metal, rubber, etc., that you push against to make the bike go.  Then someone invented a clip that extended around the toe of your shoe, holding your foot in place so you can pull up as you pedal, as well as push down, giving you much more power.  (These are called toe-clips.)  In the eighties, people started experimenting with devices that would hold your shoe onto the pedal without a toe-clip.  These pedals came to be known as "clip-less."  So any pedal which holds onto your foot without using a toe-clip is a clipless pedal.  Make sure your shoe is compatible with the brand and style of pedal you select, as there are many different systems available.
cnc: "computer numeric control."  A computer-controlled machine which cuts and shapes metal parts.  Each part is shaped individually, so cnc is useful for small runs of bicycle parts, especially ones with complicated interior shapes which cannot be molded (cast) or forged.  Cnc does not produce the strongest product.  Forging is stronger.

coasting: The intermittent practice of riding without moving the pedals and letting gravity or your momentum carry you along. 

cockpit length: the horizontal distance from the center of the handlebars back to the center of the seattube.  Since the handlebars are often higher than the top of the seattube, measure to the imaginary line extended up through the seat.  Cockpit length is roughly the sum of handlebar stem plus top tube.


crank length: measure from the center of the pedal axle to the center of the bottom bracket.  Tall riders may use longer cranks, around 180 mm.  Shorter riders may use cranks only 165 mm long.


derailleur: a device which moves the chain from one gear to another, by dragging it sideways and "derailling" the chain.  (I say "de-RAIL-er." Many people pronounce it "de-RAIL-ih-er".)  You may have two derailleurs, a front one near the cranks to move the chain from one chainring to another, and a rear one near the rear hub, to move the chain among all your rear cogs.  Derailleurs are usually activated by a cable.

disc brakes: a brake system that presses a pad against a rotating metal disc to create friction to slow the bike.  Disc brakes are more expensive than caliper brakes, but the disc works better in wet and muddy weather, resists "fading" on extended downhill runs, and works on wheels with a damaged rim.  The disc must be kept pristinely clean.

double-butted: When the metal wall of a bicycle frame is not the same thickness throughout, but is thicker at the end, we say it is "butted."  If the tube is thicker at both ends, we say it is "double-butted."   The manufacturing process requires an adjustable "mandrel" or plug to be drawn through the tube making the tubing thinner at specified locations.  The manipulation of the metal, by the way, also changes the characteristics of the metal, so there is more to double-butted tubing than just the thickness.  It is difficult to tell double-butted tubing from the outside of the frame, and even with a cut-away, the difference may be fractions of a millimeter, so you have to rely on the integrity of the frame label.  Different manufacturers and several models within a manufacturer's line have different specifications for thickness and composition.  And occasionally, a manufacturer may create flat sheets of metal with variations in thickness, and then roll the metal into tubing with a seam along its length, technically double-butted.  This is generally not considered to be the same high quality as seamless tubing.  See also the website for Reynolds.

downhill: a style of riding agressively directly downhill, over all manner of jumps and obstacles.  Also the bike designed for such activity, with long-travel shock absorbers, extra-heavy-duty brakes and wheels, and not very wide-range gears, since the direction is down the hill anyway.

downtube: the part of the bicycle frame that connects the headtube to the bottom bracket.

drivetrain: all the parts of the bike transmitting power from the pedals to the wheels.  These parts would include the cranks, chainrings, bottom bracket, chain, rear cogs (cassette or freewheel), and two derailleurs.

dropout: the metal plates on the fork and the rear of the bike that the axles are fixed to.  Dropouts must be of hard metal to withstand the forces of the axles and nuts or skewers, and they MUST be exactly perfectly parallel, or the axle will bend and break.  The right side rear dropout may include a derailleur hanger to mount a rear derailleur.  Since this dropout may be vulnerable in a crash, mountain bikes often have a replaceable right rear dropout.  Horizontal dropouts have a horizontal slot for the rear axle and allow an adjustment of the wheel fore and aft.  Special bolts or other fittings may set the rear axle in only one place.  Vertical dropouts are easier to remove the rear wheel, and may allow a shorter wheelbase.

effective: a nominal measurement which may not actually measure the item described, as in "effective chain stay length" which includes part of the rear dropout and bottom bracket. 

531: Reynolds' description of their manganese molybdenum tubing.  (Not the Reynold's aluminum company.)  I think all 531 tubing was "double-butted" (q.v.) 531was state of the art for both race and touring bikes from around 1970 to around 1984, when Columbus gradually took over the high-end market.  My favorite bike of all time was an English road bike made of 531. 

fixed cup: Usually on a bottom bracket, the side of the cup-and-cone system that is screwed in all the way and not adjusted.  It is usually on the right side of the bike, and usually has a left-hand thread, but sometimes a right-hand thread, just to make life interesting for bike mechanics.

forging: a method of shaping bicycle parts by forcing a piece of solid metal to flow within a mold under tremendous pressure.  Forged metal parts are very strong, but cannot have complicated shapes and may not have an attractive finish.  Sometimes parts are first forged and then machined to alter the shape. 

4130: The metallurgists' label for chrome-molybdenum steel.  It is harder and stronger than 1030, so you can use less of it to make a sturdy bike.  Tubing made of "chrome-molly" is often "double-butted" which enhances the cycling advantages even more.

freehub: In order to "coast" or "freewheel" on a bicycle, most systems use a ratcheting mechanism.  For many years, the mechanism was part of the cogset.  This freewheeling cogset unit was called a "freewheel," and it screwed onto the hub.  Modern systems, which have a separate ratcheting mechanism that attaches to the rear hub without the cogs, make it easier to change and clean the cogs and the hub can actually be made stronger.  The hub with this ratcheting mechanism attached without the cogs, is called a "freehub."  The ratcheting mechanism can usually be removed from the hub for replacement, but it is often difficult to do and rare to find and therefore expensive.

freewheel: 1. To coast or proceed without moving the pedals. 2. The mechanism which allows this, specifically a cluster of several gears attached to an internal ratcheting device permitting the chain to turn the rear wheel forward, and also permitting the rear wheel to turn forward while the chain remains still.

goody shifters: bar-cons.  Gear levers attached to the ends of the handlebar, usually by a plug that is inserted inside the end of the handlebar.

grupetto: see "autobus."

head angle: the headtube angle.

head badge: The manufacturer's name and/or logo affixed to the front of the head tube.  It used to be riveted on, but now it may be a decal or even painted.

headset: The two ball-bearing assemblies, one at the top and and one at the bottom of the head tube, which carry the load of the front of the bicycle and which allow the fork to rotate.  Precise installation and adjustment of the headset is necessary for safe and long-lasting service.  First, the surfaces of the top and bottom of the headtube must be perfectly parallel.  Then the cups must be inserted carefully.  (Some new headsets have a cup permanently installed as the lower part of the headtube.)  Part of the lower headset assembly is actually installed onto the crown of the fork and then the whole thing is put together.  On a threaded fork, adjustment of the headset is done by turning the top of the upper headset assembly.  On a non-threaded fork ("aheadset"), adjustment is done by placement of the handlebar stem in the correct position.

headtube: The front part of the bicycle frame that connects the top tube and the downtube.  The fork extends through the headtube, emerging at the top to connect with the handlebar stem.  The outsdie of the headtube may have a head badge attached.  The top and bottom of the headtube hold the ball bearing assemblies called the headset.  Headtubes are usually angled back about 16 to 19 degrees from the vertical (usually described as 71 to 74 degrees from horizontal.)

headtube angle: The angle the headtube makes with an imaginary horizontal line.  As the headtube approaches vertical (as the angle becomes larger,) steering becomes overly sensitive and the bike is difficult to ride.  As the angle becomes more relaxed (as the angle becomes smaller,) steering is less sensitive and becomes more forgiving on adverse conditions, but the bike is less lively.  Most adult bikes have a headtube angle from 71 to 74 degrees.

hi-tensile steel: see "ten-thirty" (1030).


investment cast: see "casting."

laughing group: see "autobus."

left-hand thread: threads which require you to turn the screw counter-clockwise to tighten.  Do NOT use the old phrase, "Righty-tightie; leftie-loosie."  It's opposite.  Places you may find a left-hand thread on a bicycle are the left pedal, the right (fixed) side of a three-piece bottom bracket, the left (adjustable) side of a one-piece bottom bracket, and the rear cog lock-ring for a track bike, as well as occasional other places.  Spokes do NOT have a left-hand thread, but you may be looking at them upside down, so turning the nut (nipple) counter-clockwise might be tightening, depending on your vantage point.

lost wax process: see "casting."

Madison: a kind of track race, from its original venu, Madison Square Garden in the 19th century.  Also called an "Americaine."  Each member of a two-man team would alternate with the other in competing, while the other would continue riding non-aggressively, resting .

mandrel: The metal plug drawn through bicycle tubing creating variations in the thickness of the metal wall.

nipple: the nut on the end of a spoke that tightens the spoke.

105: Shimano's model name for recreational race componentry.  It works great and some parts are compatible with other Shimano models.  Shimano changes specs frequently, so exact replacements are hard to do.

right-hand thread: threads on a bolt which require you to turn the nut clockwise to tighten, like screwing in a light-bulb. "Rightie-tightie; leftie-loosie."  All nuts and bolts in the world are designed with a right-hand thread, unless specified otherwise, or unless the engineer surprises you.
seamless tubing: Bicycle tubing that does not have a welded seam along its length.

7000 series aluminum: An alloy of aluminum containing zinc.  Less expensive than 6000 series because it does not require heat-treatment after welding.

6000 series aluminum: An alloy of aluminum containing magnesium and silicon, which requires heat- treatment after welding before the bicycle frame is usable.  Considered an improvement over 7000 series.


squadra: (Italian) team.

1030 (ten-thirty): The metallurgists' label for "hi-tensile" steel.  This is the most economical material of which to make bicycles, but you need more of it to make a sturdy bike.  It is easy to weld and repair.  Also, it rusts, so you have to keep the frame painted.  We find 1030 steel on low-end bikes and bike parts.

time-trial bars: another name for aero-bars, q.v.

triangle bolt: a cable carrier, or triangle-shaped hook device, that bolts to the brake cable and pulls a transverse cable moving the brake calipers inward toward the rim.

yoke: cable carrier, also called a triangle bolt.



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