How do ebikes work? An electric bike is a bicycle with three added parts: a battery that stores energy, a motor that turns it into extra push, and a controller that decides how much help to give. A sensor tells the controller when you are pedaling (and on many bikes, how hard), so the motor adds power while you pedal and stops at a set speed. Some e-bikes also have a throttle that runs the motor without pedaling.
This guide explains each part in plain English, how pedal assist and throttles differ, whether you have to pedal, and what the numbers on a spec sheet mean. We use the published specs of the bikes we carry as examples.
The main parts of an electric bike
To understand how an electric bike works, start with its parts. Under the paint, every e-bike has the same building blocks:
- Motor. Either in the rear (or front) wheel hub, or between the pedals at the crank (a mid-drive). It adds force to the wheel or to the chain.
- Battery. A lithium-ion pack, usually mounted on or inside the down tube or on the rear rack. Most can be removed for charging.
- Controller. The electronic box that reads the sensors and your settings and sends the right amount of current to the motor.
- Sensor. A cadence sensor (detects that the pedals are turning) or a torque sensor (measures how hard you press), and sometimes both.
- Display and controls. A handlebar screen and buttons to switch the system on, choose an assist level and see speed and battery charge. Many bikes add a throttle.
Everything else, from the frame, gears and brakes to the wheels, works much like a regular bicycle, just built stronger to handle the extra weight and speed.
How do ebikes work when you pedal? Pedal assist explained
Pedal assist (often shortened to PAS) is the core of how an e-bike works. When you start pedaling, the sensor sends a signal and the controller switches the motor on. You choose how much help you want with assist levels on the display, usually from 1 (a little help) to 5 (the most). Higher levels feel easier but drain the battery faster.
Cadence sensors vs torque sensors
A cadence sensor only knows that the pedals are turning. Once they turn, the motor delivers a set amount of power for the chosen level, whether you push gently or hard. It is simple and lets you ride with very little effort, but the motor can feel like it switches on rather than builds up.
A torque sensor measures the force on the pedals and adds power in proportion, so pushing harder gets you more help. Most riders describe it as closer to riding a normal bike. Some bikes let you choose: Himiway lists switchable torque and cadence modes on the Himiway D5 2.0 and the Himiway A7, while the Himiway A3 and B3 use a torque sensor.
Where the assist stops
The motor does not help forever. In most US states, Class 1 and Class 2 e-bikes stop assisting at 20 mph and Class 3 bikes at 28 mph. Above that speed you can keep going on leg power alone. The Himiway D5 2.0 family ships at 20 mph and can be set anywhere from 4 to 28 mph to match Class 1, 2 or 3 rules, according to Himiway. The Italwin and Wayel bikes we carry are built to the European standard: 250 W motors whose assist stops at 25 km/h (15.5 mph). Our guide to e-bike classes and laws covers the classes in detail, and how fast electric bikes go covers top speeds.
Do you have to pedal an electric bike?
Only if it has no throttle. A throttle, either a thumb lever or a twist grip, tells the controller to run the motor without any pedaling, like a scooter. E-bikes with a throttle that stop helping at 20 mph are Class 2 in most states. Without a throttle, the motor only runs while you pedal, so you always contribute some effort, even on the highest assist level.
Most of the Himiway bikes we carry have a thumb throttle, including the A3, B3, A7, Zebra, D5 Pro and D7. The Himiway Escape Pro uses a half-twist throttle. The Italwin and Wayel models we carry do not list a throttle in their published specs, so they are pedal-assist bikes.
Riding on the throttle alone uses the battery faster. Himiway lists the D5 2.0 at up to 70 miles on pedal assist but up to 40 miles on throttle only, which shows how much your legs add.
Hub motors vs mid-drive motors
Where the motor sits changes how the bike feels:
- Hub motors sit in the rear wheel and push the wheel directly. They are common, simple and work with any gear. The A3 uses a 500 W geared hub motor rated at 86 Nm of torque; the D5 2.0 uses a 750 W hub rated at 90 Nm.
- Mid-drive motors sit at the pedals and drive the chain, so they work through the bike’s gears. That helps on steep climbs and keeps weight low and central. The Himiway A7 Pro has a 500 W mid-drive rated at 130 Nm, and several Italwin models, such as the K2 MAX use the FIVE F90 mid-drive, a 250 W motor rated at 90 Nm.
Watts describe the motor’s power rating; newton-meters (Nm) describe twisting force, which you feel most when starting and climbing. For buying advice on motor types, see our post on how to choose an electric bike.
How the battery works: volts, amp-hours and watt-hours
An e-bike battery is a pack of lithium-ion cells. Three numbers describe it:
- Voltage (V), usually 36 V or 48 V, which the motor system is designed around.
- Amp-hours (Ah), a measure of how much charge it holds.
- Watt-hours (Wh), the total energy: volts multiplied by amp-hours. This is the best single number for comparing batteries.
For example, a 48 V 15 Ah pack holds 720 Wh (A3, B3, A7, A7 Pro), a 48 V 20 Ah pack holds 960 Wh (Zebra, D5 Pro, D7, C3 cargo bike), and the K2 MAX’s 36 V 10.5 Ah pack holds 378 Wh. More watt-hours generally means more range, but rider weight, hills, wind, tire pressure, temperature and assist level all change the result. Our long range electric bike guide shows how to estimate range from watt-hours, and our battery guide covers charging and lifespan.
Do electric bikes charge when you pedal?
Usually not. Most e-bikes, including every model we carry, recharge only from a wall outlet with the supplied charger. A few e-bikes with direct-drive hub motors offer regenerative braking, which recovers some energy when you slow down, but it does not replace charging, and none of the bikes we sell lists it. Plan to plug in after rides. Charging times vary by battery and charger; Wayel quotes about 7 hours for the 614 Wh battery on the Wayel NEXT+.
The US Consumer Product Safety Commission advises using only the charger provided or recommended by the manufacturer and staying present while a battery charges (CPSC micromobility safety).
Can you ride an e-bike with a dead battery?
Yes. With the system off, an e-bike is a regular bicycle, just a heavy one. Some hub motors add a little drag, and the extra weight makes hills harder. Weight matters here: Italwin lists the Nuvola Lite 26″ at about 43 lb without the battery, while Himiway lists the A3 at 68.3 lb and the D5 2.0 at 92 lb. Use a low gear and expect slower progress.
What makes an e-bike legally a bicycle
The federal consumer-product definition of a “low-speed electric bicycle” covers bikes with working pedals, a motor under 750 W, and a top speed under 20 mph on motor power alone (15 U.S.C. 2085). Road and path rules are set by states, and most use the three-class system with a 750 W limit, as in California (Vehicle Code 312.5). A bike with a larger motor, such as the 1000 W D7 or D7 Pro, may not count as an e-bike in states that use that cap. Laws vary by state and change, so check the PeopleForBikes state law summary and your local rules.
The rest of the bike: gears, brakes and tires
The motor helps, but the bicycle parts still matter. Gears let you keep a comfortable pedaling speed, which makes the motor more efficient. Brakes work harder because e-bikes are heavier and faster, so many use hydraulic disc brakes; on the D5 2.0, pulling a brake lever also cuts motor power. Wider tires and suspension add comfort and grip. If you want to see how these parts differ across bike types, browse our commuter and city e-bikes and fat tire e-bikes.
FAQ
Do you have to pedal an electric bike?
Not if it has a throttle. A throttle runs the motor without pedaling. Pedal-assist-only bikes (Class 1 and Class 3) need you to pedal for the motor to help, though even light pedaling gets you assistance.
Can you ride an electric bike without pedaling uphill?
On a bike with a throttle, often yes on moderate hills, but steep hills drain the battery quickly and can strain the motor. Pedaling in a low gear along with the throttle or assist is easier on both.
Do e-bikes recharge while you ride?
Most do not. Only a few direct-drive hub motors have regenerative braking, and it does not replace charging. None of the bikes we carry lists it, so you charge from an outlet.
What is pedal assist on an e-bike?
Pedal assist is the mode where the motor adds power only while you pedal. You pick the level of help on the display, and the motor stops helping at the bike’s assist speed limit.
How long does an e-bike battery last on one charge?
It depends on battery size, assist level, terrain and rider weight. Manufacturers’ range figures are best-case estimates; our battery guide and long range guide explain how to estimate yours.