The following glossary defines terms as they are used in our course materials and presentations.

Barrel adjuster

The hollow bolt that a cable passes through, allowing the increase or decrease of cable tension without re-anchoring the cable anchor bolt in a brake or derailleur system.

Bead (tire)

A rigid steel, or foldable synthetic (aramid or kevlar) wire that is moulded into the inner diameter of a tire that engages and secures the tire to the rim.

B-tension screw

The screw that adjusts the angle of the rear derailleur body, fine-tuning the distance between the guide pulley and the cogs in the cassette. Also known as the Body angle screw.

Bottom bracket

A set of ball bearings that allow the crankset to rotate around the bottom bracket spindle.

Brake noodle

A curved aluminium tube used to direct the brake cable in a linear pull (v-brake) caliper.

Brake pad

A rubber piece that engages the sidewall of the rim causing the wheel to stop. On a mechanical caliper brake, it is the piece that attaches to the Brake shoe. In a disc brake system, it is the piece that inserts into the caliper and engages the rotor when braking.

Brake shoe

The piece that holds the brake pad and attaches to the caliper. Also known as a Brake pad carrier.

Brake boss

A stud for mounting cantilever, u-brakes or linear pull brakes to a frame or fork. Also known as a Brake post.

Brake reach

The distance from the center of the brake mounting hole to the center of the braking surface on the rim.

BSD, Bead seat diameter

The diameter of a rim where the tire bead engages the hook of the rim.


A metal ring (often coated with friction reducing material) that acts like a bearing, used in suspension systems. Usually found in suspension pivots, between fork stanchions and sliders, shock shafts and seal heads, between chain links and chain pins, and even in some pedals.

Butyl rubber

A synthetic rubber made by polymerization of isoprene and isobutylene. Used in inner tubes and as an airtight coating in tubeless tires.

Cable anchor bolt

A bolt used to secure a cable.

Cable housing

The casing through which a cable is routed.

Caliper brake

Any type of brake that features a pincer-type mechanism and a single mounting point to the frame or fork.

Carbon fibre

The common name used to refer to plastic reinforced by a graphite textile. A carbon fibre is a long, thin strand of material about 0.0002—0.0004 in (0.005—0.010 mm) in diameter and composed mostly of carbon atoms. Several thousand carbon fibres are twisted together to form a yarn, which may be used by itself or woven into a fabric. The yarn or fabric is combined with epoxy and wound or molded into shape to form various composite materials.


The structural fabric of a tire.


A collection of cogs that mount on a freehub.

Center pull brake

Any type of brake where the mechanism is actuated from a central point.


The imaginary line that runs through the center of the drive train, parallel to an imaginary line that bisects the frame.


A cog or sprocket that mounts to the crank arm spider.

Chainring bolt

A bolt used to attach a chainring to the crank arm spider or another chainring.


A type of tire and rim system where the tire bead mounts onto the rim by engaging a hook on the rim.

Clipless pedal

A type of pedal which attaches to a shoe by means of a cleat on the sole and a retention mechanism integrated into the pedal.

Coaster brake

A type of hub brake that is activated by pedaling the cranks backward.


A sprocket used on a cassette or freewheel.

Cold forging

A process of forming parts by using compressive forces to shape the metal. The metal never heats up beyond 1/3 of its melting point.

Connecting pin

A specially designed chain pin used to join chain links together.

Cottered crank

A type of three-piece crank that utilizes a tapered wedge bolt – known as a cotter – to attach the crank arms to the spindle.


A device that moves the chain from cog to cog or chainring to chainring. Traditionally mechanical, increasingly electronic.

Disc brake

A type of brake that utilizes a rotor mounted to the hub, and a piston-type caliper mounted onto the frame or fork.

Disc brake caliper

Part of a disc brake system that houses the brake pads.

Disc brake mounting tab

Mounting points on a frame or fork to which the disc brake calipers attach.

Disc brake rotor

A metal disc which disc brake pads engage in order to slow or stop the wheel.


Fixtures at the rear of the frame or ends of fork legs which engage the hub axles of a wheel.

Drum brake

A type of cable-actuated brake that uses radially mounted brake shoes to engage the interior surface of a drum mounted to the hub.

Dual pivot caliper

A brake caliper that has a single mounting point and two pivot points.


A measurement of the hardness of various plastics and rubber.

Effective top tube length

The imaginary length of a top tube based on a horizontal line from the center of the top of the head tube to the center of the seat tube.


The increase in a material’s length after it is subjected to an axial pulling force.

Expander bolt

A bolt used to secure the height and rotational alignment of a quill stem.

Expander wedge

Part of a quill stem that works in conjunction with the expander bolt to secure the height and rotational alignment of the same quill stem.

Fatigue strength

The maximum stress a material can endure for a given number of stress cycles before it breaks or permanently deforms.


A metal or plastic cap that fits over the end of a cable housing.

Fixed cup

The bottom bracket bearing cup used in loose ball bearing systems that threads into the drive side of a frame and tightens against the face of the bottom bracket shell.

Fork boot

A protective cover typically used to protect suspension fork stanchion tubes.

Fork crown

A structural part of a fork that connects the steerer tube and the fork legs.

Fork leg

Tubes connecting the dropouts to the fork crown.


A ratcheting drive mechanism that forms part of a rear hub.


A single cog or a cluster of cogs mounted on a ratcheting mechanism that threads onto a rear hub.

Foot pound (symbol:

A unit of energy, equal to the work done by a force of one pound when its point of application is one foot from the axis of rotation.

Guide pulley

The upper pulley located in the cage of a rear derailleur. The guide pulley guides the chain as it engages the cog.

Handlebar drop

A measurement taken from the center of the flat top portion of a road handlebar to the center of the bottom of the drop.

Handlebar reach

A measurement taken from the center of the flat portion of a road handlebar to the center and most forward reaching section of the drop – where the brake levers mount.

Handlebar rise

The vertical measurement taken from the center of the stem clamping area to the center of the grip.

Handlebar sweep

The amount that the ends of a handlebar angles back towards the rider. Measured in degrees.

Head tube angle

The angle between the head tube and level ground. Steeper head tube angles equate to quicker steering and shallower angles equate to slower steering. Measured in degrees.

Head tube length

The measurement from the top to bottom of a head tube.


A bearing assembly located in the head tube of the frame tasked with facilitating the smooth rotation of the steering assembly.

Headset stack height

A measurement of the visible portions (top and bottom) of the headset assembly that sits outside the head tube.

High limit screw

A screw that sets and limits the position for a derailleur as it moves away from the centerline of the frame.


The central part of a wheel that houses the axle and bearing assembly.

Hub brake

Any type of brake that utilizes the hub as a part of the braking mechanism.

Hub flange

The portion of a hub which extends perpendicular from the axle, to which one end of the spokes are attached.

Inch pounds (symbol: In.lbs)

A unit of work or energy, equal to the work done by a force of one pound when its point of application is one inch from the axis of rotation.

Inner cage — front derailleur

The portion of the front derailleur that moves the chain from the smaller chainring to a larger chainring.

Inner cage — rear derailleur

The portion of the rear derailleur that houses the guide and tension pulleys.

Integrated headset

A bearing assembly that utilizes a machined bearing seat in the head tube of a frame.


A lightweight, synthetic material that is strong yet supple. Primarily used as a bead in folding tires, but also used in tire casing to increase protection against punctures.

Kilograms of force -centimeter (symbol: Kgf-Cm)

A measure of torque in which one kilogram of mass is converted to a unit of force by multiplying by the average gravitational value of 9.81 m/s².


A milky fluid found in many plants, such as poppies and spurges, which exudes when the plant is cut and coagulates on exposure to the air. The latex of the rubber tree is the chief source of natural rubber.

Linear pull brake

A type of cantilever brake in which the cable is pulled horizontally to activate the brake.


A threaded ring that is used to secure a component.

Low limit screw

A screw that sets and limits the stopping position for a derailleur as it moves towards the centerline of the frame.


Also referred to as ‘sliders’, these are the lower legs of a telescoping suspension fork.

Master link

Universal removable chain links used in the installation of single-speed chains.

Missing Link

Universal removable chain links by KMC, used in the installation of multi-speed chains.

Newton (symbol: N)

The metric standard measure of force. One Newton is the amount of force required to accelerate a mass of one kilogram at a rate of one meter per second squared.

Newton meters (symbol: Nm)

A measure of torque, equal to one Newton of force acting on a one meter lever.

Noodle carrier

A pivoting mechanism mounted on a linear pull brake arm to which the brake noodle attaches.


The acronym for Original Equipment Manufacturer. An OEM is a company whose products are used as components in the products of another company.

One-piece crank

A type of crank in which the crank arms and spindle are incorporated into one piece.

Outer cage – front derailleur

The portion of a derailleur that moves the chain from a larger chainring to a smaller chainring.

Outer cage – rear derailleur

The portion of a derailleur that houses the guide and tension pulleys.

Pinch flat

A puncture that occurs when the tire is compressed so much that the inner tube is “pinched” between the obstacle and the top of the rim’s sidewalls. Also referred to as a “snake bite” due to the two small holes characteristic of this type of puncture.

Platform pedal

A type of pedal designed to the used with flat, soft-soled shoes.

Presta valve

The Presta valve (also called French valve) is a type of pneumatic tire valve developed by the French for use on bicycle inner tubes. Utilizes a knurled nut to close the valve.


The vertical portion of a stem used with a threaded headset.


The outer part of a wheel – attached by spokes to the hub – to where the tire is mounted.

Rim brake

Any type of brake that utilizes the rim sidewall as a braking surface.

Rim strip

A strip of cloth, rubber, or plastic used with clincher rims to protect the inner tube from being punctured by the spokes or rim drillings.

Schrader valve

The Schrader valve (also called American valve) is a type of pneumatic tire valve used on virtually every motor vehicle in the world today. The Schrader valve consists of a valve stem into which a poppet-style valve core and spring is threaded.

Seat tube angle

The angle of the seat tube relative to a horizontal plane.

Seat tube length

The length of the frame tube that houses the seat post. Measured from the center of the bottom bracket shell to the center of the top tube. Alternative measurements might be taken from the center of the bottom bracket shell to the top of the top tube, or the top of the seat collar.

Self-extracting crank bolt

A type of crank arm bolt that utilizes a shoulder bolt and an aluminum dust cap, eliminating the need for a crank arm extractor.

Semi-integrated headset

A type of headset assembly that utilizes bearing cups that are pressed into (inside) the head tube of a frame.

Side-pull brake

Any type of brake that is actuated from the side.

Single pivot brake

A type of caliper brake that features a single, central pivot mechanism.


A short, slender or tapered shaft used in pedals and bottom brackets.

Spline cranks

Any type of cranks where the arms are designed to be used with a splined spindle.

Splined spindle

A type of bottom bracket spindle that utilizes splines for engagement with the crank arms. Spline count can range from 8 to 48, but must always match the spline count of the crank arms.


One of the rods or braces that connect the hub and rim of a wheel.

Square taper cranks

A type of crank arm that is designed to be used with a square taper bottom bracket spindle.

Square taper spindle

A type of bottom bracket spindle where the ends feature a four-sided, slightly tapered (2°) design.


The upper tubes of a telescopic suspension fork. Usually houses the damper and spring assemblies.


A nut that is driven into the steerer tube to allow for bearing adjustment in a treadless headset system.

Steerer tube

The section of a fork that connects the crown and fork legs to the headset and stem.

Stem length

The distance from the center of the stem’s steerer tube clamp to the center of the stem’s handlebar clamp.

Stem reach

The horizontal distance from the center of the stem’s handlebar clamp to the center of the fork steerer tube.

Stem rise

The vertical distance between the center of the steerer tube clamp and the center of the stem’s handlebar clamp.

Tension pulley

The lower pulley located in a rear derailleur cage that is tasked with taking up chain slack and maintaining tension in the chain.

Three-piece crank

Any type of crankset in which the crank arms are separate from the spindle.

Thru axle

A large diameter, hollow hub axle that passes “thru” the hub. The increased stiffness provides better wheel tracking.


An adjustment that places the leading edge of the brake pad in contact with the braking surface prior to the trailing edge. The resulting difference, or gap between the trailing edge and the braking surface is about 0.5—1.5 mm.

Top cap

The part of a threadless headset that sits on top of the stem and supports the preload bolt. Also referred to as the preload cap.

Top tube length

A measurement taken from the centerline of the head tube to the centerline of the seat tube along a horizontal plane.


A force that tends to cause rotation.

Torque wrench

A tool for setting and adjusting the tightness of nuts and bolts to a desired value.


A type of screw head characterized by a 6-point star-shaped pattern.

Threads per inch (abbreviation: TPI)

A measurement which counts the number of threads over a one inch distance. For tire casings, TPI refers to the number of threads contained in one square inch of fabric.

Transverse cable

A cable that spans cantilever brake arms and links them to a central brake cable. Also referred to as a straddle cable.


The rubber portion on the circumference of a tire that makes contact with the ground.

Two-piece crank

Any type of crank in which the spindle is permanently attached to one of the crank arms.

Vernier caliper

A measuring device that consists of a main scale with a fixed jaw and a sliding jaw with an attached vernier.

Work hardening

Also known as strain hardening or cold working, work hardening is the strengthening of a metal by deliberately or accidentally deforming it. A spoke that is repeatedly bent at a single point undergoes work hardening, and eventually breaks when the deforming force increases beyond the elastic limit of the material and succumbs to plastic (permanent) deformation.