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Reference

Glossary

Short, plain-English definitions. Each term links to the guides that cover it properly.

1

16 CFR 1512 · also federal bicycle rule
The US federal rule that sets requirements for bicycles themselves, excluding track bicycles and one-of-a-kind bicycles. Section 1512.16 requires bicycles, other than sidewalk bicycles, to carry reflectors. It is a product rule, not a riding law. Read more: Bike accessory recalls and safety rules: coin cells, pumps and chargers, Bike light and reflector rules in the US and Canada: examples, not a list

A

Affiliate disclosure
A statement that a site earns a commission from its links. FTC staff guidance says a site with affiliate links should disclose the relationship clearly and conspicuously, and the closer the disclosure is to the recommendation, the better. Read more: Buying bike accessories on Amazon or AliExpress: sellers, returns and import costs, Fit and buying
Air bleed button (Lezyne ABS) · also ABS, Air Bleed System
A button that releases trapped pressure from a pump hose. Lezyne says its ABS (Air Bleed System) button lets the chuck come off without unthreading the Presta valve core. Read more: Presta valve core came out with the pump head? Removable cores and core tools, Dual-valve pump heads: what "Presta and Schrader" really covers
ANSI/PLATO FL 1 · also FL 1, FL1
A voluntary test standard for portable lights. As Streamlight explains it, runtime runs until output falls to 10 percent of the 30-second value, beam distance is where the beam falls to 0.25 lux, and each company runs its own tests. Read more: Bike light runtime: maker claims, ANSI FL 1 and what reviewers recorded, Maker claims vs measured results: how to read bike accessory specs
Authorized dealer · also authorized retailer
A retailer or distributor a brand has approved to sell its products. Lezyne's US warranty and Topeak's warranty apply only to products bought through their authorized dealers or retailers. Read more: Buying bike accessories on Amazon or AliExpress: sellers, returns and import costs, Fit and buying

B

bar
A metric unit of pressure used on many tire sidewalls, rims and pump gauges. One bar is 100 kilopascals (kPa). Read more: Pump max psi vs your tire's and rim's pressure limits, Bike pumps
Beam pattern (hotspot and spill) · also hotspot, spill
The shape of a light's beam: a bright center (hotspot) and the wider, dimmer area around it (spill). road.cc photographs each front light's beam on the same dark lane with fixed camera settings so shapes can be compared. Read more: Lumens, lux and candela: what a bike light's numbers measure, Cutoff beams and StVZO: what an anti-glare bike light is
Butyl tube
The common black rubber inner tube. Park Tool says its GP-2 glueless patches work on butyl tubes and should be considered a temporary fix. Read more: Tube patch or tubeless plug? Match the repair to the tire and tube, Carry tools

C

Canadian certification mark · also CSA, cUL, cETL
A mark such as CSA, cUL or cETL showing a product was certified by an accredited body for Canada. Health Canada advises using a charger that carries a recognized Canadian certification mark. Read more: Charging and recycling bike light and electric pump batteries, Bike accessory recalls and safety rules: coin cells, pumps and chargers
Candela · also cd
The SI base unit of luminous intensity, the strength of light in a given direction. NIST says the lumen, the unit of total light output, is derived from it. Read more: Lumens, lux and candela: what a bike light's numbers measure
Case interface
The connector on a phone case or adapter that locks into a mount. Quad Lock says its Handlebar/Stem Mount works with all Quad Lock cases and Universal Adaptors; Peak Design's Out Front Bike Mount V2 uses its SlimLink system. Read more: Bike phone mounts: Quad Lock, Peak Design and SP Connect fit, and vibration, Bike mounts
Chain tool · also chain breaker
A tool that pushes a chain pin out or in to break or join a chain. Topeak's Mini 20 Pro chain tool covers chains up to 12-speed but not Campagnolo hollow-pin chains. Read more: Multitools, chain tools and tire levers: what each one covers, Carry tools
Clik Valve · also SCV, Schwalbe Clik Valve
Schwalbe's own valve system, coded SCV. Schwalbe offers many of its butyl tubes with Clik Valve, color-coded blue; its page does not say which pumps work with it, so check each pump maker's list. Read more: Dual-valve pump heads: what "Presta and Schrader" really covers, Valve finder
CO2 inflator
A head that releases compressed carbon dioxide from a cartridge into a tire. Genuine Innovations says cartridges become ice cold during release and recommends a cupped head or sheath to protect fingers from cold burns. Read more: CO2 inflators: threaded cartridges, cold heads, tubeless and TPU, Electric pump, mini pump or CO2 for your ride kit
Coin cell · also button battery, button cell, CR2032
A small, flat, round battery such as a CR2032. CPSC's button and coin battery rules require compartments holding replaceable cells to need a tool or two independent, simultaneous hand movements to open. Read more: Bike accessory recalls and safety rules: coin cells, pumps and chargers, Charging and recycling bike light and electric pump batteries
Counterfeit · also fake
A fake product sold under a brand's name. Amazon says it strictly prohibits the sale of counterfeit products and runs a Counterfeit Crimes Unit that works with brands and law enforcement. Read more: Buying bike accessories on Amazon or AliExpress: sellers, returns and import costs, Fit and buying
CPSC recall · also recall
A recall announced by the US Consumer Product Safety Commission. In November 2025 CPSC announced a recall of Lezyne Pressure Over Drive and Digital Pressure Over Drive floor pumps because the canister can forcefully eject from the base when pressurized. Read more: Bike accessory recalls and safety rules: coin cells, pumps and chargers, Fit and buying
Cutoff beam · also cut-off beam, anti-glare beam
A beam with a defined upper edge, so most of the light falls below a line instead of straight ahead at eye level. When a maker calls its light cut-off, that is the maker's own description. Read more: Cutoff beams and StVZO: what an anti-glare bike light is, Bike lights

D

Daytime running light · also running light, DRL
A light kept on in daylight. Permanently mounted running lights were studied in a controlled experiment with 3,845 cyclists in Odense, Denmark, in 2004-2005; that study covers those lights in that setting, not any product. Read more: Do daytime bike lights help? What the research measured, Bike lights
De minimis · also duty-free threshold
A value below which imports enter free of duty. As of 2026-10-14, a US executive order has suspended duty-free de minimis treatment for goods from all countries since August 29, 2025; check current CBP guidance. Canada's CBSA sets CAD $20 for postal shipments and for courier shipments from outside the US and Mexico. Read more: Buying bike accessories on Amazon or AliExpress: sellers, returns and import costs, Fit and buying
Dual-valve head
A pump head made for more than one valve type. It covers only the valves its maker names: Lezyne lists its Dual Valve floor-pump head for Presta, Dunlop and Schrader. Read more: Dual-valve pump heads: what "Presta and Schrader" really covers, Presta vs Schrader vs Dunlop: identify your valve before buying a pump
Dunlop (Woods) valve · also Woods valve, DV
A valve with a narrow stem top over a large locking ring. Park Tool says it can be inflated with a Presta-compatible head without unthreading the ring, and that it is found on less expensive bikes outside the United States. Read more: Presta vs Schrader vs Dunlop: identify your valve before buying a pump, Valve finder

E

Electric pump · also electric inflator, e-pump
A battery-powered pump with a small motor, often with a digital gauge and a preset target pressure. Its fill times are the maker's claims unless a named test measured them. Read more: Electric bike pumps: what published inflation tests found, and what they did not, Electric pump heat and TPU tubes with plastic valves, Electric pump, mini pump or CO2 for your ride kit
Extender hose
A short hose between a pump and the valve. Topeak tells E-BOOSTER DIGITAL users to fit its extender hose on TPU tubes with resin valves to keep the valve from overheating and melting. Read more: Electric pump heat and TPU tubes with plastic valves, Electric bike pumps: what published inflation tests found, and what they did not

F

Flat stem
A stem with a flat rather than round section where a mount would clamp. Quad Lock sells a Flat Bar Adaptor separately for mounting its Handlebar/Stem Mount on flat stems. Read more: Bike phone mounts: Quad Lock, Peak Design and SP Connect fit, and vibration, How to measure your handlebar diameter for a light or phone mount
Floor pump · also track pump
A pump that stands on the ground, with a long barrel, a hose and usually a gauge, used at home for regular pressure checks. Read more: Electric pump, mini pump or CO2 for your ride kit, Bike pumps
Frame bag · also frame pack
A bag that sits inside the main triangle of the frame. Apidura says frame pack size should be chosen by the frame's dimensions, not by desired carrying capacity. Read more: How to size a frame bag or top-tube bag for your bike, Bike bags
Free Return (AliExpress)
An AliExpress label on some items. AliExpress's Free Return terms apply only to items carrying the label, and AliExpress can change or remove the label at its discretion. Read more: Buying bike accessories on Amazon or AliExpress: sellers, returns and import costs, Fit and buying
Front Carrier Block (Brompton) · also carrier block
The plastic block on a Brompton's frame that front bags clip onto. Brompton says Brompton Electric uses a dedicated Front Carrier Block, so it needs an Electric-compatible Front Bag with space for the battery. Read more: Brompton front bags: standard vs Electric carrier blocks, Bike bags

G

Glueless patch · also self-adhesive patch
A self-adhesive patch that needs no glue. Park Tool says its GP-2 patches work on butyl and TPU tubes but not latex tubes or tubeless tires, and should be considered a temporary fix. Read more: Tube patch or tubeless plug? Match the repair to the tire and tube, Road and gravel ride repair kit: what to carry for your tires

H

Handlebar bag · also bar bag
A bag attached to the front of the handlebar by straps or a bracket. Check the room it leaves for cables, lights and mounts before choosing one. Read more: Bike bags
Handlebar diameter · also bar diameter, clamp diameter
The outside diameter of the bar or stem where a clamp sits, in millimeters. Measure your own with a caliper or a paper strip, and compare it with the range the mount's maker states. Read more: How to measure your handlebar diameter for a light or phone mount, Handlebar size finder
Hex key · also Allen key
An L-shaped or bit-style wrench with a six-sided tip for hex socket bolts, sized in millimeters. Read more: Multitools, chain tools and tire levers: what each one covers, Pocket torque tools for bikes: preset drivers vs adjustable wrenches
Hookless rim · also ETRTO
A rim without the hooked lip that holds the tire bead on a conventional rim. Schwalbe, citing ETRTO, says hookless road rims have a 5 bar maximum that applies even when the tire sidewall shows a higher one. Read more: Pump max psi vs your tire's and rim's pressure limits, Seating a tubeless tire vs topping it up: which pump does which job

I

Independent measurement
A result measured by a named publication or lab under stated conditions. BikeRadar's October 2026 electric-pump test, for example, describes 32 mm tubeless tires on a Zipp 303 SW wheel with a 53 psi front target. Read more: Maker claims vs measured results: how to read bike accessory specs, Electric bike pumps: what published inflation tests found, and what they did not
IP code · also IP rating, IEC 60529
The code from IEC 60529 that classifies the degree of protection an enclosure gives against solids and water. A product's IP figure is its maker's rating under the maker's stated conditions, not a waterproof promise. Read more: Bike lights, Maker claims vs measured results: how to read bike accessory specs

L

Latex tube
An inner tube made of latex rubber. Schwalbe says latex tubes should be checked before each ride, and Park Tool says its GP-2 glueless patches do not work on latex tubes. Read more: Tube patch or tubeless plug? Match the repair to the tire and tube, Pump max psi vs your tire's and rim's pressure limits
Lithium-ion battery · also Li-ion
A rechargeable battery chemistry used in many bike lights, electric pumps and e-bikes. CPSC says lithium batteries should never go in household trash or general recycling, but to a battery recycler or hazardous-waste collection site. Read more: Charging and recycling bike light and electric pump batteries, Bike accessory recalls and safety rules: coin cells, pumps and chargers
Low beam (and high beam) · also high beam, dipped beam
A headlight setting aimed lower to light the road close ahead; a high beam reaches further. Germany's StVZO section 67 requires one or two forward-facing white low-beam headlights aimed so they do not dazzle other road users. Read more: Cutoff beams and StVZO: what an anti-glare bike light is, Bike lights
Lumen · also lm
The unit of total light output (luminous flux). NIST says the lumen is derived from the candela, the SI base unit of luminous intensity. Read more: Lumens, lux and candela: what a bike light's numbers measure, Bike lights
Lux · also lx
The unit of illuminance, the light falling on a surface. For a point source it falls with the square of the distance, so a lux figure means little without the distance it was measured at. Read more: Lumens, lux and candela: what a bike light's numbers measure, Maker claims vs measured results: how to read bike accessory specs

M

mAh · also milliamp-hour, milliampere-hour
Milliamp-hour, a measure of battery charge capacity. Comparing mAh only makes sense at the same voltage; watt-hours combine both. Read more: Charging and recycling bike light and electric pump batteries, Flying or mailing a bike pump, light or CO2 kit
Maker claim · also manufacturer claim
A figure a maker publishes about its own product, under its own conditions. CYCPLUS, for example, claims the AS2 Pro reaches about 80 psi in roughly 50 seconds; that is not comparable with an independent test's time. Read more: Maker claims vs measured results: how to read bike accessory specs, Electric bike pumps: what published inflation tests found, and what they did not
Master link · also quick link
A link that joins a chain without a pin. SRAM says its Eagle PowerLock is designed for single use, can be removed only with chain link pliers, and should be replaced each time a chain is installed. Read more: Multitools, chain tools and tire levers: what each one covers, Carry tools
Maximum pressure · also max psi
The highest pressure a pump's maker rates it to reach. It is not a tire target: Topeak rates its Mountain Digital 2Stage to 300 psi in shock mode while listing its tire mode at 0-30 psi recommended. Read more: Pump max psi vs your tire's and rim's pressure limits, Electric pump, mini pump or CO2 for your ride kit
MIK · also MIK system, trunk bag
A clip-on system for fitting bags, baskets and trunk bags to the top of a rear rack. Basil lists a 15 kg maximum load for its MIK adapter plate and says the separate MIK Carrier Plate fits racks with 8-16 mm tubes and 100-170 mm outer width. Read more: Rear racks: frame fit, load limits and MIK or MTX top bags, Bike bags
Mini pump · also hand pump
A small hand pump made to carry on the bike or in a pocket. Topeak's mini-pump maximums vary by model, from 60 psi on some Mountain models to 160 psi on Roadie TT and Pocket Rocket models. Read more: Electric pump, mini pump or CO2 for your ride kit, Pump max psi vs your tire's and rim's pressure limits
MTX QuickTrack · also MTX, trunk bag
Topeak's rail system for sliding a trunk bag onto a rack. Its MTX QuickTrack Adapter 2.0 is listed for the E-Xplorer TrunkBag and the MTX TrunkBag DXP, EXP, DX and EX. Read more: Rear racks: frame fit, load limits and MIK or MTX top bags, Bike bags
Multitool · also mini tool
A folding tool that combines hex keys, Torx bits and screwdrivers, and sometimes a chain tool or tire levers, made to carry on rides. Read more: Multitools, chain tools and tire levers: what each one covers, Carry tools

O

Out-front mount
A mount that holds a computer, phone or light ahead of the handlebar. Wahoo makes its BOLT 3 and ROAM 3 out-front mount for 31.8 mm round bars and warns that over-torquing can strip its threads. Read more: Garmin vs Wahoo computer mounts: similar shape, different systems, How to measure your handlebar diameter for a light or phone mount

P

Pannier
A bag that hooks onto the side of a rack. ORTLIEB lists its Back-Roller pair at 20 L per bag with a 9 kg maximum payload per bag. Read more: Pannier fit: hook sizes, rack tube diameters and e-bike racks, Rear racks: frame fit, load limits and MIK or MTX top bags
Power bank · also portable charger
A portable battery pack for charging devices. TSA says power banks and other spare lithium batteries must travel in carry-on bags only, not checked luggage. Read more: Flying or mailing a bike pump, light or CO2 kit, Charging and recycling bike light and electric pump batteries
Pressure gauge · also gauge
A dial or digital readout of pressure on a pump or as a separate tool. Accuracy figures are maker claims: CYCPLUS claims plus or minus 1 psi for the AS2 Pro, and Topeak plus or minus 2 psi for the E-BOOSTER DIGITAL. Read more: Maker claims vs measured results: how to read bike accessory specs, Electric bike pumps: what published inflation tests found, and what they did not
Presta valve · also Sclaverand valve, SV, French valve
A thin bicycle valve with a small locknut at the top of the stem that must be unthreaded before air can enter the tube. Park Tool describes Presta stems as nominally 6 mm in diameter, thinner than Schrader stems. Read more: Presta vs Schrader vs Dunlop: identify your valve before buying a pump, Valve finder, Presta valve core came out with the pump head? Removable cores and core tools
psi · also pounds per square inch
Pounds per square inch, the pressure unit most US pump gauges show. Many tire sidewalls and pump listings give pressure in both psi and bar. Read more: Pump max psi vs your tire's and rim's pressure limits, Bike pumps
Pump head (chuck) · also chuck, threaded chuck, press-on head
The fitting at the end of a pump hose that connects to the valve. Threaded chucks screw on and press-on heads lock with a lever. Park Tool says Schrader-compatible fittings press the valve's internal stem with a plunger, and Lezyne describes its Dual Valve head as press-on with a locking lever. Read more: Dual-valve pump heads: what "Presta and Schrader" really covers, Presta valve core came out with the pump head? Removable cores and core tools

Q

Quarter-turn mount · also twist mount
A mount where the device locks on with a quarter twist. Similar-looking mounts from different brands are not automatically compatible, so check the device maker's own list. Read more: Garmin vs Wahoo computer mounts: similar shape, different systems, Bike mounts
Quick-Lock (ORTLIEB) · also QL2.1, QL2.2, QL3.1
ORTLIEB's family of pannier mounting systems. Its QL2.1 version uses 16 mm upper hooks with inserts for 8, 10 and 12 mm rack tubes. Read more: Pannier fit: hook sizes, rack tube diameters and e-bike racks, Bike bags

R

Radar tail light · also bike radar
A rear light with a built-in radar that detects vehicles approaching from behind. Garmin rates the Varia RTL515 at 65 lumens for up to 16 hours in day flash and 20 lumens for up to 6 hours solid. Read more: Bike light runtime: maker claims, ANSI FL 1 and what reviewers recorded, Bike lights
Rear rack · also carrier, pannier rack
A frame over the rear wheel that carries panniers or a top bag. Topeak lists a 22 kg (48.5 lb) maximum load for its TetraRack M2 HD; a rack's load and a bag's payload are separate limits. Read more: Rear racks: frame fit, load limits and MIK or MTX top bags, Pannier fit: hook sizes, rack tube diameters and e-bike racks
Reflector · also retroreflector
A device that returns light toward its source without power. The US bicycle rule 16 CFR 1512.16 requires bicycles, other than sidewalk bicycles, to carry reflectors so they can be recognized under motor-vehicle headlamps. Read more: Bike light and reflector rules in the US and Canada: examples, not a list, Bike lights
Runtime · also battery life, thermal step-down
How long a light runs in a mode. Under ANSI/PLATO FL 1 it is measured from 30 seconds after switch-on until output falls to 10 percent, so it is not time at full brightness. Some lights lower their output as they heat up, called thermal step-down. Read more: Bike light runtime: maker claims, ANSI FL 1 and what reviewers recorded, Bike lights

S

Saddle bag · also seat pack, seat bag
A bag under the saddle, from small tool pouches to large seat packs. Restrap's 18-liter Saddle Bag attaches to the seatpost without mounts or screws and uses a holster with a separate dry bag. Read more: Bike bags, How to size a frame bag or top-tube bag for your bike
Schrader valve · also AV, car valve, American valve
The wider, car-style valve. Park Tool gives the stem as approximately 8 mm (5/16 inch), and says Schrader-compatible pump fittings press the valve's internal stem with a plunger so the tube can fill. Read more: Presta vs Schrader vs Dunlop: identify your valve before buying a pump, Valve finder, Dual-valve pump heads: what "Presta and Schrader" really covers
Seller of record · also sold by
The business that actually sells your order, which can differ from the brand and from the marketplace. On Amazon US, a return for a third-party seller's item goes to that seller, with an A-to-z Guarantee request if it does not respond within two business days. Read more: Buying bike accessories on Amazon or AliExpress: sellers, returns and import costs, Fit and buying
Shim · also spacer, bar adapter
A thin spacer that lets a clamp fit a smaller or differently shaped tube. SP Connect includes one flat and one round diameter adapter with its Universal Bike Mount, listed for bars or stems of about 20-44 mm. Read more: How to measure your handlebar diameter for a light or phone mount, Bike mounts
Sidewall pressure range
The minimum and maximum pressure printed on a tire's sidewall. Schwalbe says this permissible range should never be exceeded or undershot. Read more: Pump max psi vs your tire's and rim's pressure limits, Bike pumps
StVZO · also StVZO approval
Germany's road-vehicle approval rules. Section 67 requires bicycles to have forward-facing white low-beam headlights aimed so they do not dazzle others, and lighting devices must meet its type-approval requirement. It is a German rule and says nothing about the US or Canada. Read more: Cutoff beams and StVZO: what an anti-glare bike light is, Bike light and reflector rules in the US and Canada: examples, not a list
SV, AV, DV and SCV · also SV, AV, DV, SCV
Schwalbe's labels for valve types on its tubes: SV for Sclaverand (Presta), AV for car valves (Schrader), DV for Dunlop and SCV for its own Clik Valve. Read more: Presta vs Schrader vs Dunlop: identify your valve before buying a pump, Valve finder

T

Threaded CO2 cartridge
A CO2 cartridge with a screw thread on its neck. Genuine Innovations says its threaded cartridges use the standard 3/8"-24 thread. Read more: CO2 inflators: threaded cartridges, cold heads, tubeless and TPU, Flying or mailing a bike pump, light or CO2 kit
Time to shutoff
How long a light runs until it switches off, which can be longer than its rated runtime. In 1Lumen's test of a flashlight, the low mode reached its ANSI-style endpoint at 7 h 29 min but kept running until 10 h 44 min. Read more: Bike light runtime: maker claims, ANSI FL 1 and what reviewers recorded, Maker claims vs measured results: how to read bike accessory specs
Tire lever
A flat tool for lifting a tire bead off the rim. Park Tool's TL-1.2 levers come as a set of three with a spoke hook, and Park Tool says the narrow tip works with tubeless systems. Read more: Multitools, chain tools and tire levers: what each one covers, Road and gravel ride repair kit: what to carry for your tires
Tire sealant · also sealant
A liquid inside a tubeless tire, or some tubes, that seals small punctures. Stan's NoTubes says prolonged CO2 exposure can make sealant separate or shorten its life, so CO2 should be replaced with air. Read more: Seating a tubeless tire vs topping it up: which pump does which job, CO2 inflators: threaded cartridges, cold heads, tubeless and TPU, Tube patch or tubeless plug? Match the repair to the tire and tube
Top-tube bag · also top-tube pack
A small bag on top of the top tube behind the stem. Apidura's Expedition Bolt-On Top Tube Pack bolts to top-tube bosses and straps around the steerer; Apidura points bikes without those bolts to its strapped version. Read more: How to size a frame bag or top-tube bag for your bike, Bike bags
Torque driver (Nm) · also Nm, torque wrench, newton-meter
A driver that clicks or stops at a set torque, measured in newton-meters (Nm). Park Tool's ATD-1.2 has settings from 4 to 6 Nm, and Topeak lists its Torq Stick Pro for 2-10 Nm with plus or minus 4 percent accuracy. Use the component maker's own torque figure. Read more: Pocket torque tools for bikes: preset drivers vs adjustable wrenches, Carry tools
Torx bit · also Torx
A driver with a six-pointed star tip for Torx bolts, sized by a T number. Check that a multitool lists the T sizes your bike's bolts use. Read more: Multitools, chain tools and tire levers: what each one covers, Pocket torque tools for bikes: preset drivers vs adjustable wrenches
TPU tube · also thermoplastic polyurethane tube
An inner tube made of thermoplastic polyurethane. Tubolito says only its Schrader (AV) valves have removable cores that accept sealant, and that repair kits made for butyl tubes are not compatible with its tubes. Read more: Electric pump heat and TPU tubes with plastic valves, Tube patch or tubeless plug? Match the repair to the tire and tube
Tubeless booster · also booster
A pump chamber or separate tank that stores air to release in one strong blast for seating a tubeless tire. Schwalbe says first inflation of a tubeless tire needs such a blast from a floor pump, compressor or its Tire Booster. Read more: Seating a tubeless tire vs topping it up: which pump does which job, Bike pumps
Tubeless plug · also tire plug, bacon strip
A strip or dart pushed into a puncture in a tubeless tire. Park Tool says its TPT-1 plug tool repairs small punctures in tubeless tires with sealant and is not compatible with inner tube systems. Read more: Tube patch or tubeless plug? Match the repair to the tire and tube, Road and gravel ride repair kit: what to carry for your tires
Tubeless tire
A tire that seals to the rim without an inner tube, usually with liquid sealant inside. Schwalbe says its first inflation needs a strong blast of air from a floor pump, compressor or Tire Booster. Read more: Seating a tubeless tire vs topping it up: which pump does which job, Tube patch or tubeless plug? Match the repair to the tire and tube

U

UL 2849
UL's standard for the electrical systems of e-bikes. It is a vehicle-system standard, not one for add-on accessories such as USB lights or pumps. Read more: Bike accessory recalls and safety rules: coin cells, pumps and chargers, Charging and recycling bike light and electric pump batteries
Universal charger
A charger sold to fit many devices. In September 2024 CPSC urged consumers not to use 'universal' chargers with e-bikes and other micromobility products, saying an incompatible charger can ignite the battery. Read more: Charging and recycling bike light and electric pump batteries, Bike accessory recalls and safety rules: coin cells, pumps and chargers
USB-C · also USB Type-C
A reversible USB connector used to charge many lights and electric pumps. The port alone does not tell you a device's charging input; check what its maker states. Read more: Charging and recycling bike light and electric pump batteries

V

Valve core
The inner part of a valve that seals the air in. Some Presta valves have removable cores, which Park Tool says can be identified by two wrench flats at the end of the valve. Read more: Presta valve core came out with the pump head? Removable cores and core tools, Presta vs Schrader vs Dunlop: identify your valve before buying a pump
Valve core tool · also core remover
A small wrench for removing and installing valve cores. Park Tool's VC-1 removes and installs Schrader and removable Presta cores, and fits Presta valve extenders with 5 mm wrench flats. Read more: Presta valve core came out with the pump head? Removable cores and core tools, Seating a tubeless tire vs topping it up: which pump does which job
Valve extender
A threaded tube that lengthens a valve so a pump head can reach it on a deep rim. Park Tool's VC-1 core tool fits Presta valve extenders that have 5 mm wrench flats. Read more: Presta valve core came out with the pump head? Removable cores and core tools, Dual-valve pump heads: what "Presta and Schrader" really covers
Vibration dampener
A part between a mount and a phone that absorbs vibration. Quad Lock describes its Vibration Dampener as designed for motorcycle mounts and says the camera-vibration issue is known with some motorcycles, not bicycles. Read more: Bike phone mounts: Quad Lock, Peak Design and SP Connect fit, and vibration, Bike mounts

W

Watt-hour (Wh) · also Wh
A measure of battery energy: volts times amp-hours. TSA limits rechargeable lithium-ion batteries to 100 watt-hours each, with airline approval needed to carry up to two spares of 101 to 160 watt-hours. Read more: Flying or mailing a bike pump, light or CO2 kit, Charging and recycling bike light and electric pump batteries