The E-Bike Glossary

The classification framework most US states use to regulate e-bikes, sorting them into Class 1, Class 2, and Class 3 based on whether the motor uses a throttle and how fast it will assist. It was first codified by California (AB 1096, effective 2016) and has since been adopted by more than 40 states.

Putting an e-bike in one of the three classes is what lets it be treated like a bicycle instead of a motor vehicle — no registration, license, or insurance in most states.

See alsoClass 1, 2 & 3 explainedState e-bike lawsLegality checker

A pedal-assist-only e-bike (no throttle) whose motor stops adding power at 20 mph (32 km/h). It is the most widely permitted class, generally allowed anywhere a regular bicycle can go, including most bike paths and many trails.

See alsoClass 1, 2 & 3 explainedState e-bike laws

An e-bike with a throttle that can power the bike without pedaling, with motor assistance capped at 20 mph (32 km/h). Both the throttle and any pedal-assist cut out at that speed.

See alsoClass 1, 2 & 3 explainedState e-bike laws

A pedal-assist e-bike that assists up to 28 mph (45 km/h) and is usually required to have a speedometer. Because of that higher speed it is the most regulated class — many states require riders to be at least 16, mandate a helmet, and keep Class 3 bikes off shared-use paths.

See alsoClass 1, 2 & 3 explainedState e-bike lawsLegality checker

A system that delivers motor power only while you are pedaling, scaling assistance to your input via a torque or cadence sensor. Pedal-assist (with no throttle) defines Class 1 and Class 3 e-bikes.

See alsoTorque vs cadence sensorClass 1, 2 & 3 explained

A control — usually a thumb lever or twist grip — that delivers motor power on demand without pedaling. Its presence is what makes an e-bike Class 2; a throttle that keeps working above 20 mph pushes the bike out of the three-class system entirely.

See alsoClass 2 e-bike

The speed at which an e-bike's motor stops adding power — 20 mph for Class 1 and Class 2, 28 mph for Class 3. You can still pedal faster under your own power; the cap only limits motor assistance, not how fast the bike can roll.

See alsoClass 1, 2 & 3 explained

The power a motor is rated to sustain continuously, expressed in watts (W). This is the figure e-bike laws regulate — the US federal limit is 750W nominal.

See alsoPeak powerState e-bike laws

The maximum short-burst power a motor can deliver — for example on a steep climb — often two to three times its nominal rating. Marketing usually advertises peak watts, but the law regulates nominal watts, so a motor sold as "1000W peak" can still be a legal 750W-nominal e-bike.

See alsoNominal power

The unit of power that describes how much work an e-bike motor can do. More watts mean more torque and hill-climbing ability but faster battery drain. E-bike laws are written in terms of a motor's nominal (continuous) wattage.

See alsoNominal power

Under US federal law (15 U.S.C. § 2085, the 2002 amendment to the Consumer Product Safety Act), a "low-speed electric bicycle" has functional pedals, a motor under 750W, and a top motor-only speed under 20 mph on a flat surface. Meeting this definition makes it a consumer product regulated like a bicycle rather than a motor vehicle.

The federal rule governs how a bike is sold and regulated for safety; where and how you can actually ride it is set separately by each state.

See also750W vs 1000W statesState e-bike laws

The federal definition caps e-bikes at 750W (1 hp) nominal, and most states match it — but a handful allow up to 1000W. A bike that exceeds the limit that applies where you ride is no longer legally an e-bike; it becomes a moped or motor vehicle.

See alsoState e-bike lawsLegality checker

Modifying an e-bike to bypass its speed limiter so the motor keeps assisting past the legal cap. It voids the warranty, is illegal on public roads in nearly every jurisdiction, and reclassifies the bike as an unregistered motor vehicle.

See alsoMoped

A motor built into the center of the front or, more commonly, rear wheel, driving that wheel directly. It is simpler and cheaper than a mid-drive and is common on commuter and budget e-bikes.

See alsoMid-drive vs hub motor

A motor mounted at the bike's bottom bracket (the cranks) that drives the chain and so uses the bike's gears. It is more efficient on hills and better balanced, which is why it is favored on cargo and premium e-bikes.

See alsoMid-drive vs hub motorTorque

The rotational force the motor applies, measured in newton-metres (Nm). Higher torque — roughly 80 to 160 Nm on capable bikes — means stronger acceleration and hill-climbing, which matters most for cargo and family e-bikes carrying loads.

See alsoMid-drive motor

A pedal-assist sensor that measures how hard you pedal and scales motor power proportionally, giving a natural, responsive ride. It is found on higher-end e-bikes.

See alsoCadence sensor

A simpler pedal-assist sensor that only detects whether you are pedaling — not how hard — and delivers a preset level of power. It is cheaper than a torque sensor but feels less natural, often surging on and off.

See alsoTorque sensor

A mode that runs the motor at walking pace (about 3-4 mph) to help push a heavy e-bike up a ramp or while you walk alongside it.

The electronic brain that regulates power flowing from the battery to the motor based on your input and the chosen assist level. It is also what enforces the class speed cap.

See alsoAssisted top speed

The unit of battery capacity, equal to volts × amp-hours. It is the single best number for comparing range potential: a 720Wh battery holds roughly twice the energy of a 360Wh one.

See alsoRangeHow long e-bike batteries last

The electrical "pressure" of an e-bike battery, commonly 36V, 48V, or 52V. Higher-voltage systems can deliver more power and often feel peppier.

See alsoWatt-hour

A measure of how much charge a battery holds. Multiplied by the voltage it gives the capacity in watt-hours — a 48V 15Ah pack is 720Wh.

See alsoWatt-hour

How far an e-bike can travel on one charge. It depends on battery capacity (Wh), assist level, terrain, rider weight, tire pressure, and wind, so manufacturer claims — which assume ideal conditions — usually overstate real-world range.

See alsoRange calculatorWatt-hour

Electronics inside the battery pack that protect it from overcharging, over-discharging, overheating, and cell imbalance. A quality BMS is central to battery safety and longevity.

See alsoUL 2849How long e-bike batteries last

One full discharge and recharge of a battery. Lithium e-bike batteries typically retain about 80% of their original capacity after 500 to 1,000 cycles.

See alsoHow long e-bike batteries last

The safety certification standard for a complete e-bike electrical system — battery, charger, motor, and controller tested together. New York City has required e-bikes sold, leased, or rented in the city to meet UL 2849 since 2023, a response to lithium-battery fires.

See alsoUL 2271BMS

The safety certification standard specifically for the lithium battery pack used in light electric vehicles such as e-bikes. It is often cited alongside UL 2849, which covers the whole system.

See alsoUL 2849

Whether a rider must wear a helmet, which usually depends on the class and the rider's age. Many states require a helmet for all Class 3 riders and for younger riders on any class of e-bike.

See alsoState e-bike lawsLegality checker

The youngest age at which a person may operate an e-bike, set by state law and most often applied to Class 3 (commonly 16). Many states set no minimum age for Class 1 and Class 2.

See alsoState e-bike lawsLegality checker

Most states treat a compliant e-bike like a bicycle — no registration, license, or insurance required. A small number require registration, and any bike that exceeds e-bike limits becomes a moped or motor vehicle that does.

See alsoMopedState e-bike laws

The legal category an "e-bike" falls into once it exceeds e-bike limits — for example more than 750-1000W of nominal power or motor assistance past 28 mph. Mopeds typically require registration, a license, insurance, and a helmet, and are barred from bike paths.

See alsoDerestrictionState e-bike laws

The common rule barring Class 3 e-bikes from bike paths and shared-use trails — allowing them only on roads and on-road bike lanes — because of their higher 28 mph assisted speed. The exact rule varies by state and local agency.

See alsoClass 3 e-bikeState e-bike laws

Electrically Assisted Pedal Cycle — the UK's compliant e-bike: a 250W maximum continuous motor, assistance that cuts off at 15.5 mph (25 km/h), and a minimum rider age of 14. An EAPC is treated as a normal bicycle, with no registration, tax, or licence.

See alsoPedelec (EU)Legality checker

The EU class of pedal-assist e-bike limited to 250W and 25 km/h (15.5 mph), treated as a bicycle. A faster "S-pedelec" that assists to 45 km/h is legally a moped, requiring registration, insurance, and a helmet.

See alsoEAPC (UK)