The federal definition
Federal law defines a "low-speed electric bicycle" in 15 U.S.C. §2085(b). It needs fully operable pedals, an electric motor under 750 W, and a top speed under 20 mph when powered by the motor alone, measured on a paved level surface with a 170 lb rider.
This is a product-safety rule. It decides which safety standards a bike is built to. It does not say where you can ride. That is up to each state.
The three classes
Most states use a three-class system first written into California Vehicle Code §312.5. Every class needs working pedals and a motor of 750 W or less. They differ in how the motor is controlled and when it stops helping.
| Class | How the motor engages | Assist stops at | Typical extras |
|---|---|---|---|
| Class 1 | Only while you pedal | 20 mph | Usually allowed wherever bicycles are |
| Class 2 | Pedaling or a throttle | 20 mph | Some trails exclude throttles |
| Class 3 | Only while you pedal | 28 mph | Speedometer required; often a minimum age and helmet rule |
States change the details. Some allow a Class 3 throttle up to 20 mph. Some ban Class 3 bikes from shared paths. Many set 16 as the minimum age for Class 3. Always read your own state's wording.
What happens to bikes outside the classes
A bike with a motor over 750 W, or one that assists past 28 mph, usually stops being a bicycle in the eyes of the law. States tend to class it as a moped, motor-driven cycle or motorcycle. That can bring registration, insurance, a license or endorsement, a helmet requirement, and a ban from bike lanes and paths.
Owning one is generally legal. Riding it on public roads as if it were a bicycle often is not. Our RidStar H20Pro review walks through a real example.
Class checker
Which class is my bike?
Runs in your browser| Definition | Rule | Result |
|---|
Example: a typical 500 W commuter with a throttle. Enter the figures from the bike's spec sheet. Use the continuous (nominal) motor rating if the maker gives one; regulators may also look at peak power.
How to read a spec sheet for legality
- Motor watts. Look for "nominal" or "rated" power. A large "peak" figure with no nominal rating is a warning sign.
- Top assisted speed. Ignore "top speed" claims that include downhill or pedaling hard. You want the speed at which the motor cuts out.
- Throttle. A "pure electric mode" counts as a throttle.
- Class label. Many states require a sticker showing the class, top speed and motor wattage. If the maker won't say which class, ask why.
- Certification. Look for UL 2849 (whole bike) and UL 2271 (battery). New York City requires both for sale.
This guide is general information, not legal advice.