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Rad Power Bikes Production Site

Glossary of terms

The following terms are frequently used in documentation from Rad Power Bikes.



Allen bit

A bit with a hexagonal head. The Allen bit must be attached to a wrench, ratcheting wrench, torque wrench, or other similar device.

Allen wrench

A tool used for tightening and loosening bolts with a hexagonal head sockets. Allen wrenches come in a variety of sizes described, in the bike world, in millimeters (ex: 4 mm Allen wrench). Also called an “Allen key,” “hex key,” or “hex wrench.”

alternating current

A type of movement or flow of an electric charge. Alternating current (AC) changes direction and voltage polarity, and is the power supplied by household outlets/power plants. See also "direct current."


A unit quantity of electricity equal to the quantity carried past any point of a circuit in one hour by a steady current of one ampere.


Base unit of electric current.


The component at the center of the hub that connects the wheel to the dropouts of the bike frame. The axle can attach via a quick release mechanism or nut/bolt mechanism that requires tools.

axle spacer

A piece of hardware that slides onto an axle to create space between components.

backing nut

A nut on the back of the cable pinch bolt that clamps against a mechanical bike cable to hold the cable in place.


Illumination from behind or the source of that illumination. Not to be confused with "taillight," which is the light on the back of a vehicle.

ball bearing

Ball (steel or other material) used to reduce friction between moving parts. Usually used in the plural (ball bearings) or shortened to "bearing," though bearing is a more general term for a machine component (ball, roller, etc.) used to reduce friction and/or constraint relative motion.

barrel adjuster

A component on each mechanical brake lever and caliper that is used to remove cable stretch. They are also located on some gear shifters and derailleurs where they are used for micro adjustment of cable tension as well as to remove cable stretch.


An energy storage device with components that deliver a specific voltage and current capable of powering an electric motor.

battery capacity gauge

An indicator on the LCD display that shows an estimate of how much charge the battery has at that moment.

battery level indicator light

An indicator on the LED display that shows an estimate of how much charge the battery has at that time.

battery management system

An electronic circuit that protects the battery for safe operation, typically found on "smart" batteries.

battery mount

A mount on the frame that supports the battery and allows the battery to connect to the bike's electrical system.

battery receptacle

The connector located at the end of the battery mount.

bicycle grease

Substance used to lubricate certain bike parts.

bolt head

The head of a bolt, which features a larger diameter than the shank of the bolt. Bolt heads come in different styles/shapes (e.g., button head, socket head, hex head, flat/countersunk head). Bolt heads can also have different drive types

bottom bracket

Collective term for the axle-like components that the cranks rotate, transmitting force to the chainring, the chain, and the rest of the drivetrain. Consists of the "bottom bracket shell," the tube that's open at each side of the bike and is located at the conjunction of the downtube, seat tube, and chainstays. The rest of the bottom-bracket assembly (the bottom bracket spindle and bearings, etc., depending on the specific design) passes through the bottom bracket shell and connect to the cranks. See also "bottom braket shell" and "bottom bracket spindle."

bottom bracket shell

. See also "bottom bracket" and "bottom bracket spindle."

bottom bracket spindle

The rotating axle that runs through the bottom bracket shell and connects to each crank/pedal.

brake cable

Steel cable encased in protective plastic tubing that transmits pressure exerted on a brake lever to the brake calipers and disc rotor.

brake caliper

One of two "jaws" located at each wheel. When a brake lever is depressed, the caliper squeezes the brake pads against the brake rotor to slow or stop the wheel.

brake hose

Hose that contains hydraulic fluid and that links the brake lever with the brake calipers, transmitting brake-lever compression to the calipers.

brake lever

A lever component (on each side of the handlebar) that the rider squeezes to slow the bike.

brake lever sensor

A sensor inside the brake lever that sends a signal to the controller to cut off motor power when the lever is squeezed. See also "motor cutoff."

brake lever sensor cable

A cable that carries an electrical signal from the brake lever sensor to the controller when a brake lever is squeezed, cutting off power to the motor.

brake light

A light on the back of a vehicle that illuminates when brakes are engaged. See also "taillight."

brake pad

The components inside each brake caliper that make contact with the brake rotor when a brake lever is squeezed, causing friction that slows the bike.

brake pad retention

The retention or retaining of the brake pads to the caliper, often referring to a method of retention. Also used as a compound adjective to modify the specific type of hardware used to retain the brake pads, e.g., "brake pad retention pin." See also "brake pad retention pin"

brake pad retention pin

A pin that secures the brake pads in position on the brake calipers.

brake rotor

A metal disc attached to the wheel hub that rotates between the brake pads. When a brake lever is squeezed, the brake pads clamp onto the brake rotor, causing friction that slows the bike.

brake-pad separator

A tool used to create space between the hydraulic brake pads.

brushless motor

A motor type that has no wear points other than the bearings and is therefore more mechanically simple, yet more expensive, than motors with brushes.

cable cover

A removable cover that keeps cables tidy and protected. Not to be confused with cable housing. Contrast with "cable housing" and "wiring harness."

cable crimp

Piece of hardware that is secured, via crimping or pinching (e.g., with pliers), over the end of a metal cable to prevent fraying or slippage.

cable guide

A structure on a bike or an item added to a bike. Used to secure a cable (e.g., brake cable).

cable housing

The weather-resistent external tube that holds and protects a cable (e.g., brake cable). Sometimes called the "conduit" or "cable conduit."

cable-pinch bolt

A bolt and washer that, when tightened, secure a cable in position.


Pedaling rate. Can be used to determine whether pedal assist is applied (in devices that include a cadence sensor).

cadence sensor

Sensor that detects the bike rider's rate of pedaling (rotation of cranks per unit of time). Compare with "torque sensor."


Non-bike-specific term for one of two "jaws" that comprise a device either for a measuring or for pressing frictional material against the sides of a rotating wheel or disc. Usually used in the plural (calipers) to refer to the entire device.

caliper adapter

A specialized piece of hardware that allows a brake caliper to be mounted to a particular bike frame.

caliper arm

The "jaw" or "arm" component of a caliper. See also "caliper."

captive flat washer

Flat washer that is pre-insalled on a fastener (e.g., bolt) and cannot be removed.

captive split washer

Split washer that is pre-installed on a fastener (e.g., bolt) and cannot be removed.

captive washer

A washer that has been “pre-loaded” onto the shaft of a screw or bolt during manufacturing and cannot be removed.


Objects/weight carried by a bicycle other than the bicycle itself, the rider, or passengers.


The sprockets (stacked set of gears or cogs) on the rear wheel. When a rider shifts gears, the derailleur moves the chain to another cog on the cassette.

castle axle nut

A type of nut secured with a cotter pin.

Center Console

Accessory made for the RadRunner: Container with lid. Installs between the seat tube and the downtube.


Linked metal pieces. On a bike, the chain is a loop that transfers power from the pedals/front chainring to the rear wheel.

chain tensioner

A device that applies force to the chain to maintain correct tension. Typically used on single speed bikes (on multi-speed bikes, the derailleur provides correct tension on the chain).

chain-tensioner bashguard

A component that protects the chain-tensioner from impacts.


A piece comprised of pins, plates, and rollers that links to other pieces to form the chain.


The circular metal disk with teeth that grab the chain links and is revolved by the pedal cranks.


The part of the frame that runs parallel to the chain.

chainstay brace

Part of the bike frame that provides extra stability to the chainstays by connecting the two chainstay sides near the rear wheel. Also called a "chainstay bridge."


A device for charging batteries.

charging port

A receptacle on the battery to plug in the charger to charge the battery.


The base frame of a motor vehicle.

clamp bolt

A type of bolt used to secure a part in place by forcing it against an immovable part.

commuter bike

A bike used for commuting in an urban area.

cone spring

A spring shaped like a cone, with one wide and one narrow end.


A component created by plugging in two matching cable ends.

connector terminal

The metal pins inside a connector.


The "brain" of the ebike. The controller allows electrical components to communicate and controls the motor.

controller carrier

Component that attaches to the controller used on ebikes with semi-integrated batteries. The controller carrier makes it easier to insert and position the controller in the downtube.

cotter pin

A pin that goes through a castle nut to provide security against loosening by vibration, and secures disc brake pads in place. See also "castle axle nut."


One of two metal arms that connect each pedal to the chainring/bottom bracket to move the bike forward when pedaling.

crank arm

One of two metal arms that connect each pedal to the chainring/bottom bracket to move the bike forward when pedaling.

crank arm mount

The protruding, square-shaped part on either side of the bottom bracket spindle on which the crank arm is mounted.


A rotating part of a drivetrain consisting of the front chainring, cranks, and pedals. The crankset allows the bike to move forward when a rider is pedaling.


A fundamental concept of electricity that describes the movement or flow of an electric charge. Direct current (DC) flows in one direction with a constant voltage, and is the current delivered by an AA battery, for example. Alternating current (AC) change

Deckhand (Legacy)

RadWagon 2019 accessory that attaches to the rear rack and provides a handhold for passengers. Contrast with "Deckhand."


A spring that connects the front fork of a bicycle to the frame to keep the wheel from "flopping" when parked on the kickstand, keeping the bike stable.


The mechanism that moves the chain from cog to cog.

derailleur bashguard

A component that protects the derailleur from impacts. See also "chain tensioner."

derailleur cable pinch bolt

A mechanism that uses a bolt and washer to secure the end of the derailleur cable. See "cable pinch bolt."

derailleur limit screw

One of three adjustable screws that change the derailleur's range of motion and height. Correct adjustment can help to prevent the chain from falling off the wheel-side and derailleur-side of the cassette or freewheel.

direct current

A type of movement or flow of an electric charge. Direct current (DC) flows in one direction with a constant voltage, and is the current delivered by an AA battery, for example. See also "alternating current."

direct drive motor

A type of motor that has no gear reduction. Compared to a geared motor, it is more efficient at higher speeds, slightly slower when starting, and slightly quieter when riding. See also "gear reduction" and "geared motor."

disc brake

Type of braking system that uses calipers to squeeze brake pads around the sides of a brake rotor to slow the bike. See also "rim brake" and "hydraulic brake."


The part of a bike frame that connects the head tube to the bottom bracket.

drive side

The side of the bike that includes certain parts of the drivetrain including the chain and the derailleur or chain tensioner.


A system of parts that delivers power to the axle. On a bike, this can include the chain, freewheel, derailleur, etc.


Part of the frame at the front fork and back of a bike frame that is designed to hold the wheel axle.

dual-leg kickstand

A kickstand that has two "legs," one extending from each side of the bike. When deployed, the bike rests on the kickstand and whatever wheel (front or back, but usually the back) closest to the bike's center of gravity.


Short for "electric bicycle"—a bicycle that can use electricity, stored in a battery, to propel the bicycle.

elevated rear seat

Optional passenger seat for RadRunner models.

extension cable

A cable segment specifically designed to increase the length/reach of another cable.

external cable cover

The long, rectangular, black component that bolts to the bottom of the downtube of Rad Power Bikes “Plus” models including RadCity 5 Plus and RadRover 6 Plus. It protects the wiring harness cable, rear brake cable, and shifter cable.

extreme riding

Riding techniques and stunts that include but are not limited to jumps, wheelies, or any riding that exceeds your capabilities or the strength of specific bike parts or joints. Extreme riding can result in bike damage and/or personal injury or death.


Small, eye-shaped loop in a component. Often used for connecting one component to another.


A plate that protects a piece of machinery or electronics. Frequently used for the front-facing component that wraps about halfway around the handlebar and fastens to the stem in order to secure the handlebar. See also "stem faceplate."


A semicircle of plastic or metal that, when installed, is positioned over the wheel of a bike and blocks water, mud, and other debris from spraying up from the tires onto a rider and cargo.

fender mounting arm

A lengthy piece of hardware that helps attach and align a fender correctly to the frame/rear wheel or fork /front wheel.

flash mode

A mode that involves flashing. Some bikes from Rad Power Bikes include a button on the backlight that causes it to flash continuously, which can improve visibility of the bike.


A flat tire/tube.

flat washer

A flat, round piece of hardware with a hole in the middle. Used on a bolt or screw to distribute clamping force over a larger area.

flat-side cutters

A tool similar in shape to pliers, with a flat cutting edgs used to snip zip ties excess flush against the zip tie locking mecahnism.

folding stem

A handlebar stem that folds, as on RadMini and RadExpand models.

folding handlebar stem

A handlebar stem that folds, as on RadMini and RadExpand models.


The front portion of the bike frame to which the front wheel is attached.

fork arch

The fork arch connects the top of the two fork lowers. Sometimes called a "fork brace." See also "fork" and "fork crown."

fork crown

The top part of the fork where the two fork blades join each other and merge into the steerer tube.

fork dropout

One of two dropouts on each fork lower that hold the wheel axle.


The metal tubing that connects all of the bike components and supports the weight of the rider.

frame folding mechanism

Name for the entire folding mechanism located on the frame of a folding bike. Compare to "stem folding mechanism."

frame hinge

The hinge that is part of the folding mechanism on the frame of a folding bike (e.g., the RadMini). See also "folding handlebar stem."

frame stand

A small, triangle-shaped metal part below the bottom bracket. It protects the crank in certain situations, such as when a RadMini is folded.


A mechanism that threads onto the hub and allows the gear/sprocket to be propelled when a rider pedals forward, but also allows the rear wheel to continue to rotate when a rider stops pedalling or pedals backward. See also "cassette."

front rack

Rigid structure on the front of a bike (either built-in or added as an accessory) that is designed to support cargo.


A metal disc with teeth that grab and revolve the chain.


Alternative term for "gear."

gear reduction

A motor feature in which a smaller gear (a "reduced" gear) with fewer teeth drives a larger gear with more teeth. This reduces the rotary speed of the output, but increases torque.

geared hub motor

A geared motor located on the hub. See also "geared motor," "gear reduction," and "hub motor."

geared motor

A type of motor that uses gear reduction. Bikes with this type of motor have more low-end torque, start slightly more quickly and more efficiently, and are slightly louder than a direct-drive motor. See also "gear reduction" and "direct drive motor."


A flexible ring or loop that strengthens or protects an opening.


The bar that the rider holds onto and uses to steer the front wheel and bike.

handlebar grip

A part of the handlebar, one on each end, designed for the hand to grip.

handlebar stem

The horizontal tube that connects the handlebar to the steering column.


Light on the front of a bike or other vehicle. Used to increase visibility of the bike and also illuminate the path of the vehicle.


A system inside the headtube of the bike that uses ball bearings to allow the fork steering column and front wheel to rotate and turn.


The part of the bike frame that connects the front fork and the handlebar.


Wind blowing in the opposite direction of a traveler.


Bike frame with a traditional, horizontal or nearly horizontal top tube, requiring a high leg lift, usually swinging a leg over the rear of the bike, to mount. See also "step-through" and "mid-step"

hinge pin

A small metal cylinder that a hinge rotates around.


The hollow cylinder in the middle of a wheel.

hub motor

A motor located at the center of a wheel. Contrast with "mid-drive motor."

hydraulic brake

A brake system in which hydraulic fluid, not a mechanical cable, is used to transmit the brake force from the brake lever to the caliper to slow the bike.


Act of igniting. Used to describe the start-up process for internal-combustion engines like those in most cars. Not an accurate term for any start-up component in an electric vehicle such as an ebike. See also "keyport."

insertion point

In the context of bicycles, "insertion point" refers to how far one component is inserted into another component (e.g., how far the seatpost is inserted into the seat tube). The maximum insertion point will be marked on seatposts as a safety warning.

integrated brake light

A brake light that is integrated with some other component or bike frame.

internal cable cover

Component that is bolted inside the downtube in order to cover and protect the cables that run in the side channels. Present on bikes with semi-integrated batteries.


A mechanical device designed to lift a heavy object.

jockey wheel

The two pulleys near the rear wheel that take up slack from the bike chain, creating an S-shape in the chain next to the derailleur.


The slot on the battery or frame for bikes with semi-integrated batteries where you insert a key.


A swiveling metal bar or bars that can be used to prop up a bicycle when it is not in use. See also "dual-leg kickstand."

LCD display

On some bikes from Rad Power Bikes, the LCD display is a device, located on the handlebar, that shows information including speed, watt output, pedal assist level, and odometer. LCD stands for "liquid crystal display."

LCD display remote

The remote on the left side of the handlebar that allows the rider to interact with the LCD Display and related functions (e.g., adjust pedal assist level or turn on the headlight).

lead acid battery

An older, heavier battery technology used in early model electric vehicles (not used in any bikes by Rad Power Bikes). Compare to lithium-ion battery.


An acronym for "light-emitting diode." Rad Power Bikes uses this technology in the taillight, headlight, and LED display. See also "LED display."

LED display

Display that uses LED technology. Present on some bikes by Rad Power Bikes, where it is located on the handlebar and displays pedal assist levels and other information. See also "LED."

lithium-ion battery

An advanced, rechargeable battery technology that has a high energy density (a lot of capacity in a compact battery), no memory effect (the battery won't be damaged with frequent use/charging), and low self-discharge (the battery will maintain its charge

lock core

The complete unit that houses a lock mechanism, including cylinder, tumblers, springs. etc. Often has a "figure eight" shaped when viewed from the front, where the key is inserted.

lock mount

Mount for a lock.

lock-on grip

Handlebar grips that secure via a bolt instead of friction alone.

locking pin

Pin used in a locking mechanism.


A nut specifically designed to resist loosening by vibration.

lockout lever

Available on some front suspension forks. The lockout lever can "lock" the fork so that it does not absorb shocks. This can make pedaling more efficient but can make your ride feel bumpier.


A notched, circular component that's reverse-threaded to prevent the brake barrel adjusters or another component from coming loose.

mechanical brake

A brake system in which braking force is transmitted by a cable mechanism.

mechanical disc brake

A disc brake system in which braking force is transmitted by a cable mechanism.

metal mounting tab

Tab, made of metal, configured to facilitate mounting. Similar to a small bracket.

mid-drive motor

A motor located at the center of a bike, typically between the pedals. Compare to "hub motor."


Bike frame with a top tube that is fairly low or that angles down from the head tube toward the middle of the seat tube. More accessible than a high-step frame as it provides a lower standover height.


A low-powered motorcycle that can have pedals; considered a motorized vehicle requiring a license, insurance, and other requirements depending on local laws.

motor cutoff

A feature that cuts off all power to the motor when a brake lever is squeezed.

motor drive assembly

General term for the motor and components (hardware, electrical) that connect the motor to the bike and its electrical system.

motor hall fault

A type of error that has to do with wires in the motor or the motor's communication with other bike components.

mounting arm

A lengthy piece of hardware that attaches one part to another part or stabilizes the position of a component. See also "fender mounting arm."

mounting bolt

A bolt used to mount one component to another.

mounting window

A window-like opening designed for mounting something. For instance, many of the rear racks for Rad Power Bikes contain a mounting window compatible with the Thule Yepp Maxi child carrier.

needle nose pliers

Type of pliers that has long, tapering jaws with pointed tips, often used for gripping small items.

nitrile gloves

Protective gloves recommended for use during assembly.


An instrument that measures distance traveled. Models with an LCD display have an odometer readout showing total distance traveled by that bike. Compare to "trip odometer."


Unit of electrical resistance.


A bag that can be mounted on your rear rack to carry cargo.

passenger peg

Peg used as a footrest for comfort and safety. Example: The RadRunner includes folding passenger pegs.

passenger seat

A seat for a passenger. Term used for the rear rack passenger seat accessory made for the RadRunner. Use "deckpad" for the RadWagon rear rack seat cushion for passengers.


The weight carried by a product, not including the weight of the product itself

payload capacity

The maximum recommended amount of weight that a product can safely support (not including the weight of the product itself). Payload capacity on a bicycle can vary depending on how weight is distributed. See your bike manual for more specific information.


The component that a rider presses their feet against and rotates to propel the bike.

pedal assist

A system that speaks to the motor to provide power based on the rider’s pedaling.

pedal assist sensor

The electronic device used to detect a rider's pedaling.

pedal wrench

An open-ended wrench, thinner than regular open-ended wrenches, and designed to fit into the tight space between pedal and crank. Recommended for use to tighten pedals. To achieve a specific torque value, use a torque wrench with a pedal wrench bit (aka "crowfoot" bit). 

pedal wrench bit

Special type of bit used with a socket, ratcheting wrench, or torque wrench. Shaped like a pedal wrench (open-end wrench/spanner) and thin enough to fit between crank and pedal. Used, for instance, in conjunction with a torque wrench to torque a pedal to a specific torque value.

Phillips head screwdriver

A screwdriver with an "x" head.

pinch flat

A type of flat caused by the tube being pinched between the rim of the wheel and a hard riding surface. This is more likely to occur when tires are inflated below the recommended tire pressure. When changing this type of flat, look for two near identical cuts on each side of the tube which resemble a snake bite.

plate spacer

Plastic wedge/packaging element. Example: A plate spacer is used to keep the hydraulic brake pads (i.e., on the RadBurro) from compressing (clamping shut) during shipping.

pneumatic support

Type of spring or damper that uses air pressure to provide support.

pneumatic tire

A type of tire that holds air and must be inflated to the pressure listed on the tire sidewall.

preload adjustment knob

On some bikes with a front suspension fork, the preload adjustment knob is a device that allows you to adjust the resistance of the suspension fork from softer to tighter. See "lockout lever" and your owner's manual for more information.

programming cable

A cable/dongle used to program the controller during manufacturing.

puncture flat

A type of flat caused by a sharp object stabbing the tire and tube. Typical causes are thorns, thistles, sharp rocks, broken glass, tacks, and other sharp objects. Tire liners can help decrease the likelihood of puncture flats happening, but cannot preven

puncture-resistant tire

A tire (tyre) with features designed to prevent sharp objects from fully penetrating the tire and causing a puncture to the tube inside.

push-release wheel

The two wheels that are installed on the RadTrailer. The wheels are installed in the trailer's axle receiver by holding the push-release button.

quick release

A lever that enables adjustment or removal of parts, like the seatpost and front wheel, without tools.

quick release skewer

A lever and metal rod that is installed in the front wheel hub and allows for removal of the front wheel without tools.


A rigid structure on a bicycle used for supporting cargo and, in some cases, passengers.

ratcheting wrench

A type of wrench that ratchets, making it possible to tighten or loosen a fastener without having to reposition the wrench repeatedly.

rear rack

A bicycle rack located at the back of the bicycle, above the rear wheel. Used for supporting cargo and, in some cases, passengers.

reflective sidewall striping

Striping on the side of a tire that is designed to reflect light, increasing bike visibility and safety.


A component that light bounces off of and back to the source of light. Used on bikes to increase the bike's visibility, must be attached and visible at all times, and may be required by law.

regenerative braking

A method for converting part of the braking energy into a small amount of battery capacity.

repair stand

A device designed to secure a bike, most commonly off the ground, for maintenance activities.


The metal ring that holds the tire and is connected to the hub by spokes under tension.

rim brake

A type of brake system that uses calipers to press frictional material against the bike rim in order to slow down wheel rotation.

caliper brake

Brake that uses calipers, but in some legacy materials used to describe rim brakes. Not a useful term because almost all brake systems use calipers. Use more specific terms instead. See "disc brake," hydraulic brake," or "rim brake."

rim strip

A strip of material on the inside of the rim that protects the inner tube from being punctured by the spoke holes.

roll pin

A pin-shaped component that rolls.

rolling resistance

The drag or force resisting the movement of a wheel across a surface. All wheels will eventually slow down due to resistance of moving parts against each other.


The seat of a bicycle.

safety strap

Webbed strap that wraps around the bike's chain stay to provide an emergency/temporary backup method of trailer attachment to the bike in the unlikely event that the trailer arm detaches from the hitch

Schrader valve

A common type of pneumatic tire valve.


The bike component designed for the rider to sit on.

seat adjustment bolt

A bolt under the seat that, once loosened, allows the seat to be adjusted.

seat mounting bolt

A bolt that secures the seat to a custom mount.

seat tube

The part of the frame that the seatpost slides into.


The long metal tube that connects to the seat and slides into the seat tube.


A part of the frame which connects seat tube to the rear dropout.

seatstay brace

Part of the bike frame where the two sides of the seatstay join, usually in an arch, just above the rear wheel.

semi-integrated battery

Battery that is partially integrated into the bike frame.

set screw

A small screw used for making adjustments to parts including brake calipers and brake levers.


The shank of a fastener (screw or bolt) is the entire fastener minus the head.

shift gear

To transition from one gear to another. See "gears."

shift lever

A lever at the handlebar that is used to shift gears.

single-speed bike

A bike that has only one gear.

skid plate

A flat plate designed to skid along another surface. On a bike, a skid plate may be installed underneath sensitive components to protect them from accidental exposure to riding terrain (bumps, rocks, etc.).

split washer

A washer that is split one one side, with the two edges offset. Also called a "lock washer."


One of many metal rods that connect the rim to the hub of a bike wheel.

steerer tube

The upper part of the front fork that goes into the head tube and attaches to the turning parts of the headset and handlebar stem to allow steering.


The horizontal tube that connects the handlebar to the steering column inside the headtube.

stem angle

The angle of the stem relative to the head tube.

stem angle adjustment bolt

The bolt that lets you loosen, adjust, and secure the angle of the handlebar stem. Available only on bikes with adjustable stem angles (e.g., RadCity 4, RadWagon 3).

stem clamp bolts

Bolts that secure the stem to the steerer tube on most bikes. In the case of a bike with a stem riser, the stem clamp bolts attach the stem to the stem riser.

stem clasp

Clasp mechanism of the folding stem. Consists of a roll pin inside the stem clasp release lever that rolls over an adjustable hex bolt inside the stem.

stem clasp release lever

A lever that locks or unlocks a folding mechanism, such as the handlebar stem on a RadMini or RadMini Step-Thru.

stem faceplate

A plate used to secure the handlebar to the handlebar stem. See also "faceplate."

stem folding mechanism

The entire folding mechanism on a folding handlebar stem.

stem riser

Component that connects the steerer tube to the stem. Not present in all bike designs. Examples of a bike with a stem riser: The RadMini and the RadMini Step-Thru.

stem riser clamp bolts

Bolts that secure the stem riser to the steerer tube.


A frame design without a top tube. Allows a rider to mount the bike with a low step in front of the seat rather than swinging a leg over the seat/ back of the bike.


To damage a bolt or screw head by letting the tip of the driver slip out of the head while turning, expanding the opening that the driver must fit into snuggly. This mostly commonly occurs when the driver is not fully inserted into the bolt head when force is applied.

stripped bolt head

A bolt head whose drive slot(s) have been damaged by a driver slipping out of the slot and distorting the slot shape such that it can no longer be easily turned by the driver.

suspension fork

A front fork with built-in shock absorption.

suspension seatpost

A seatpost with built-in shock absorption.


A light, located on the back of a vehicle that increases the vehicle's visibility.

telescoping seatpost

A seatpost that comes in more than one section, one of which can slide into the other section. Provides a greater range of height adjustment.

terminal contact

One of several contact points through which power from a battery passes to the device that uses battery power.


A spiral groove used for fastening. Usually used in the plural (threads). When used in the singular, usually refers to a one full circumference of such grooves.

When used as a verb, to turn a threaded object (e.g., a screw or bolt) into another material or a threaded mount.


Having threads (spiral grooves used for fastening)


Collective noun (gerund) for threads.


Liquid applied to fastener threads to increase their resistance to loosening via vibration.


The spiral grooves on a fastener (like a screw or bolt).


A feature that allows the rider to manually call up power from the motor and battery without pedaling. Controlled by a device on the handlebar.

twist throttle

Non-preferred term for "throttle."

thumb nut

A type of nut designed to be easy to grip (i.e., with your thumb/fingers).


The round rubber/fiber casing for the inner tube that connects to the rim and that the wheels roll on.

tire bead

A ridge molded on the edge of the tire that keeps the tire attached to the rim when the tube is inflated.

tire sidewall

The side of a tire, which provides lateral stability and helps protect the layers of the tire as well as the pneumatic inner tube.

top cap

Cap that conceals and protects the top-cap bolt, which attaches the handlebar stem to the steerer tube.

top cap bolt

Bolt that attaches the handlebar stem to the headset/steerer tube inside of the headtube. Called the "top cap" bolt because it passes through the top cap, which is what seals off the headtube and its contents from the elements.

top cap bolt cover

Small cover (usually in the form of a flexible plug) that covers and protects the head of the top cap bolt, which would otherwise be exposed in the center of the top cap.

top tube

The portion of the bike frame that connects the headtube with the seat tube. On a step-thru frame, the top tube slopes down toward the bottom bracket.


A rotational force. Used to describe tightening a component or hardware to a specific value.

When used as a verb, to apply rotational force.

torque arm

Piece of hardware that resists the twisting forces that a hub motor creates when you apply power to the motor. The large opening that fits over the axle of the hub motor will have an irregular shape (e.g., round but with two sides flattened) to ensure it stays in its intended position. The smaller opening is bolted to the frame. See also "torque washer."

torque sensor

Sensor that detects the *force* that the rider applies to the cranks. Compare with "torque sensor." Compare to "cadence sensor."

torque value

A specific amount of rotational force, typically measured in "newton meters" (Nm).

torque washer

A type of asymetrical washer with a protruding tab that helps resist the torque force between the axle and the frame. See also "torque arm."

torque wrench

A torque wrench is a tool used to apply a specific torque (rotational force) to a fastener such as a nut or bolt.


The part of the tire designed to come into contact with the road (or other surface).


A vehicle with three wheels.

trip odometer

A feature that measures how far a bike has traveled during a specific interval, shown on the LCD display.


Describes a spinning component, such as a wheel, that spins straight, without any wobble. See also "truing" and "untrue."


The process of adjusting a spinning component (such as a wheel or disc rotor) so that it spins straight, without any wobble. See also "true" and "untrue."


Inflatable, usually ring-shaped rubber component that holds air inside the tire. Sometimes called "inner tube."

turn-signal light

Light used to indicate that the vehicle is about to turn.

twist power assist

A system that allows the rider to manually call up additional power from the motor and battery while the rider is pedaling. Do not confuse with throttle, which can deploy power without the rider pedaling. Compare to "throttle."

Universal Serial Bus

A connector standard for many computers, mobile phones, and other electronics.


A component that wobbles when spinning. See also "true" and "truing."

USB port

Port for connecting a USB device.


Abbreviated "V." The unit of electrical potential energy, or the difference of potential that would drive one amp of current against one ohm of resistance.


A fundamental concept of electricity that describes electric potential difference.

walk mode

A feature that allows the rider to walk beside the bike and push the bike forward with help from the motor.


Flat, circular disk with a hole in the center, placed on a bolt or screw shaft to distribute clamping force of the fastener over a larger surface area.

water-bottle cage

Rigid holder designed to contain a water bottle.


A measurement of power.

watt hour

A measurement of energy used to describe battery capacity.

watt meter

An instrument for measuring electric power.

wheel lock

A lock made specifically to secure the rear wheel to prevent unauthorized use.

wheel skirt

A shield that can be installed on the sides of a wheel to protect it (or a passenger) from damage or injury.


A nut designed to be tightened by hand (without tools).

wiring harness

An assembly of electrical cables bound by durable material. On many bikes from Rad Power Bikes, several handlebar-area electrical cables plug into one end of a wiring harness, an adapter cable that feeds into the downtube where, toward the bottom of the bike, it connects to the controller via the wiring harness connector. The wiring harness optimizes space and makes assembly and maintenance easier. Contrast with "cable housing" and "cable cover."

cable harness

Non-preferred term. Use "wiring harness" instead.

wiring harness connector

The large connector, usually located near the controller or inside the downtube, that connects the wiring harness to the controller.

wooden cargo deck

Wood panel designed for the top of the RadWagon rear rack.


A tool for holding or rotating an object (such as a bolt or nut).

zip tie

A plastic strip that can be threaded through its end and tightened in order to fasten something. Also called "cable tie" in English.

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