An e-bike display shows four kinds of information: how much battery is left, how much help the motor is giving, how fast and far you are going, and whether the system has detected a fault. Display layouts differ between brands, but the readings below appear on most of them. Read your own manual for exact symbols and error codes.
The core readings
| Reading | What it tells you | How to use it |
|---|---|---|
| Battery bars or percentage | Estimated state of charge. It is an estimate from voltage and measured current, so it can jump under heavy load and recover when you stop. | Judge a trip by the trend over several minutes, not by one reading on a hill. |
| Assist level | How much motor support is requested for each unit of your pedaling effort. Higher levels use more battery per kilometer. | Use the lowest level that keeps you comfortable; save high levels for climbs and headwinds. |
| Speed | Current speed from a wheel sensor. Assist fades out at a legal limit that depends on where the bike is sold. | If the motor seems to “let go” at a steady speed, that is the limiter working, not a fault. |
| Trip and total distance | Distance since reset and lifetime distance. | Use total distance to schedule routine checks of tires, brakes and chain. |
| Range estimate | Remaining distance predicted from recent consumption. | Treat it as a guess. It drops on climbs, in wind and at higher assist levels. |
Why assist cuts out at a set speed
The motor only helps up to a legal speed. Above it you pedal unassisted, as on any bicycle. The limit differs by region, and the US has three classes rather than one number.
- EU: the pedelec definition requires assist to be cut off before 25 km/h and caps continuous rated motor power at 250 W.
- US Class 1: pedal-assist only, assist ends at 20 mph (32 km/h).
- US Class 2: throttle-capable, assist ends at 20 mph (32 km/h).
- US Class 3: pedal-assist ending at 28 mph (about 45 km/h) in California’s definition, with a speedometer required.
A common mix-up is to think 32 km/h is the Class 3 limit. It is the Class 1 and 2 limit; Class 3 is 28 mph. Federal law separately treats a “low-speed electric bicycle” as a consumer product: fully operable pedals, a motor under 750 W, and a top motor-only speed under 20 mph. Local rules on where each class may ride vary, so check your city and state. For the full picture see our guide to e-bike laws in the US, UK and EU.
Power readings in watts
Some displays show motor output in watts. This is the electrical or mechanical power the motor is delivering at that instant, and it rises with assist level and with how hard you are working. There is no single typical value for each assist mode: it depends on the motor, the software tuning and your own effort, and the 250 W figure in the EU is a rated continuous power, not a measure of what any given mode delivers. Use the number comparatively. Note how much it climbs when you step up a level or hit a hill, and how quickly battery percentage falls as a result. Our article on real-world e-bike range explains what drives that trade-off.
Cadence
Cadence is how many times per minute your pedals turn, in revolutions per minute (rpm). Riders typically settle into a cadence at which they feel most comfortable, and on bikes with many gears you can hold that cadence across a wide range of speeds. On an e-bike this matters for a practical reason: grinding a very tall gear at low rpm is hard on your knees and, with a mid-drive motor, makes the motor and drivetrain work harder. Shift down until pedaling feels smooth rather than chasing a particular number; no single rpm range suits every rider or motor. How the system senses your effort also affects how it feels, covered in torque versus cadence sensors.
Battery level and when to recharge
There is no official “reserve” threshold on the display. What matters is how lithium-ion cells age. Battery University notes that partial discharge is fine, that shallow discharges extend life, and that you should avoid full discharges and recharge more often between uses. Its tables also show cells held at full charge lose capacity faster than those held at 40% charge, especially when warm. In practice: plan trips so you are not routinely running to empty, and do not leave the battery sitting fully charged for long periods. Always charge with the charger supplied for your battery. More detail is in our battery care guide.
Error codes and warnings
A code or warning icon means the system detected something outside its normal range, such as a sensor, communication or battery-related fault. Codes are manufacturer-specific, so the manual or the brand’s dealer is the only reliable key. Safe first steps: switch the system off, check that the display and battery are seated properly, and restart. If the code returns, the motor cuts out, the battery is hot, swollen, smells or is damaged, stop using the bike and take it to a dealer. Do not open the battery or motor housing, and do not bypass any protection. If you are unsure whether a problem is the battery or the charger, see why an e-bike battery won’t charge.
Firmware and apps
Many systems accept updates through the manufacturer’s app or at a dealer. Use only the official app or dealer for your system, and update with the battery well charged and the bike stationary.
Sources
- Wikipedia: Electric bicycle laws
- Cornell LII: 15 U.S. Code § 2085 – Low-speed electric bicycles
- Wikipedia: Cadence (cycling)
- Battery University: BU-808: How to Prolong Lithium-based Batteries
Last reviewed: October 2026.