The electric bike world is filled with terminologies that might confuse newcomers to the sport. However, these terms are often crucial to understanding before purchasing an electric bike and can help you maximize your ride’s efficiency, enjoyment, and safety.
Shedding Light On E-Bike Jargon
With that in mind, we’ve compiled a list of commonly used e-bike and cycling terms that we frequently use in our reviews, along with their explanations, to make it easier to understand.
Amps or Amperes
An ampere is the base unit of electrical current. An ampere is equivalent to a charge of one coulomb per second. The following formula gives the power of the circuit:
P (Watt) = V (Volt) × I (Ampere)
Rearranging the above equation, we can calculate the value of electric current as follows:
I (Ampere) = P (Watt) / V (Volt)
A common example is a 36-volt motor system driving a 500-watt motor, meaning 500 watts divided by 36 volts would use up to 13.88 amps of current.
Ampere hours measure battery capacity, generally shortened to amp hours or Ah. The larger the amp hours listed, the more energy the battery stores. It measures how many hours a battery can put out 1 amp or how many amps a battery can put out in one hour.
The battery comprises individual cells whose chemical reactions create a flow of electrons in a circuit. Commonly found in e-bikes, these are lithium-ion cells that are put together in both series and parallel to create enough power to drive the motor at a given power output and do so for a long enough period to offer a good range. The battery can be attached on the outside of the frame, often either on top of the downtube, behind the saddle on a rack, or integrated into the downtube.
Although most e-bikes use a traditional chain drive system, which connects the front chainring to the rear gears, quite a few bikes use drive systems with a rubber belt replacing the chain. Unlike a chain that is joined by a series of links (and a master link to connect it), belt drives are made from a single loop of rubber that is favored for quiet driving and very low maintenance.
Cargo bikes are designed well to carry cargo, whether it be your briefcase for work, your groceries, your camping gear, or even your kids. They often have sturdy front or rear racks where you can attach bags, kid seats, packages, and more. Some cargo bikes come with a large bucket in front and are made for carrying massive amounts of groceries, supplies, or multiple kids.
Batteries are generally made up of multiple cells. This generally means lithium-ion batteries for electric bicycles, and usually, the size is 18650 because the cells are 18mm x 65mm. Some newer bikes now use larger 21700 batteries (21mm x 70mm). Therefore, those batteries have a higher capacity and offer a higher potential range.
Any time you fully discharge and recharge a battery, it’s considered a charge cycle. Any time you partially discharge a battery, it’s a partial cycle. Batteries are usually rated for 500 to 2,000 charge cycles before they will no longer have enough capacity to be useful. It’s worth considering this when you buy a bike; ask if replacements may be available in a few years. Companies like Bosch and Yamaha have made the same form-factor batteries for many years, so even an older bike with one of those systems can get new life through a new battery.
Class 1 E-Bike
PeopleForBikes partly developed the American e-bike classification to help states have a standardized way to classify e-bikes to make it easy to legalize e-bikes for various types of roads, paths, and trails. Class 1 is pedal-assist only and can go up to 20 mph. Most electric mountain bikes are Class 1. As a side note, the same type of bike in Europe is limited to 25 km/h (15.5 mph).
Class 2 E-Bike
Class 2 follows the same rules as Class 1, but it also has a throttle, so it can go up to 20 mph regardless of whether the rider pedals or not.
Class 3 E-Bike
A Class 3 e-bike can have pedal assist at speeds up to 28 mph and can only be legally used on the street or designated bike paths. It can also be equipped with a throttle, but with a throttle only, it can only go up to 20 mph.
These are electrical connections between motor, battery, and controller. They often have quick-disconnect plugs to make it easy to diagnose problems with various parts of the system.
Some motor systems have apps that let you connect a smartphone app and/or control the system using your smartphone. For example, Shimano has the e-Tube app that enables you to change the mode settings to add or subtract power levels in each mode. Bosch also has a display designed by Cobi that allows the rider’s smartphone to customize controls and offers a bigger screen with more information than most other displays. Connectivity can not only talk to the bike but also help add GPS maps and other information.
This is essentially the “brain” of the bike. It connects the electronic parts of the drivetrain, including motor, battery, throttle, torque sensor, and cadence sensor. It takes their inputs, plus the mode/power level you’ve selected, and pulls current from the battery to offer the motor the right pedal (or throttle) assistance.
Since the motor is running off of a DC, or direct current battery, the motor will also be a simple direct-current design. Alternating current, or AC, is better suited to powering devices in the home, like lamps or televisions.
This is the shape of the majority of bicycle frames. It has a front triangle that is comprised of a head tube, top tube, downtube, and seat tube, and attached to the rear triangle comprised of the seatstays and chainstays. The two triangles connected form a diamond shape.
Direct-Drive Hub Motor
Direct-drive hub motors are the simplest type of hub motor. The magnets are fixed on the inside surface of the hub, and the windings are permanently attached to the axle. When power is applied, the hub is made to rotate around the axle. The advantages of a direct-drive hub motor include quiet (often silent) operation, few moving parts, and the ability to regenerate power into the battery, because the magnets are always moving over the coils. However, because the motor is always mechanically engaged, there is “cogging,” a drag that can be felt while coasting. Direct-drive motors must also be larger, and usually heavier, than comparable geared hub motors to achieve the same performance.
Most e-bikes have an LCD or LED display showing battery charge level, speed, and current mode. Some offer all kinds of other information, including the rider’s torque input, cadence, battery voltage, and sometimes even more.
“Do it yourself.” There are kits that include a motor, battery, and controller, so you can convert your traditional bicycle to an electric one. Others like to go the full custom route, ordering the motor, battery, and controller separately. Some even build their own batteries, which is not a task for the faint of heart.
A seatpost that can go lower or higher via a remote switch that can be wired or wireless, depending on the rider’s needs. These are most often found on, or installed on, mountain bikes. They make it easy to drop the saddle when descending for better clearance, then raise it for the best leg position when climbing.
E-Mountain Bike (e-MTB)
An electric mountain bike is designed for off-road and trail riding. Generally, these have at least a suspension fork, but often they can also include rear suspension. Today, many are purpose-built for the specific type of riding, such as cross-country, downhill, or enduro.
A folding e-bike is usually a smaller bike that can fold in half to take up even less space. Folding frames often designed with a hinge in the middle to allow the bike to fold up on itself. Frequently, the handlebars will also fold down.
A front-drive bike has the hub motor located in the front wheel. This is rarely used on production e-bikes, but is quite common for conversion kits.
There are so many places that any bike can house its powerplant. Some rely on mid-mount motors (see below), and others rely on motors found in the wheel’s hub. While a few fringe designs locate the motor in the front hub, most are found in the rear hub. Hub motors are generally rated at 350-750 watts, and there are motors up to many thousands of watts, but 750 watts is the federal legal limit.
These motors can be direct drive, offering regenerative braking, slowing down the motor, and returning energy to the battery. Don’t expect to recharge your battery significantly with regeneration, but it can maintain a reasonable speed downhill.
The other type of hub motor uses internal planetary gears to turn the hub, make the wheel turn, and move the bike forward. These are often smaller than an equivalent-wattage direct-drive hub and can be quieter but offer no regenerative braking.
Early mountain bikes could also be easily identified by the big battery often mounted on the frame’s downtube. But as batteries reduce in size, many modern bikes, especially e-road bikes looking to maintain the traditional slender profile, are mounting them internally inside the downtube.
A switch that either detects when you stop pedaling or when you actuate one of the brake levers, which cuts all power to the motor, ensuring you can slow or stop as quickly as possible.
Most modern e-bikes, at least the ones sold in North America and Europe, use lithium-ion batteries. These batteries are lightweight, reliable, and safe. The risk of them catching fire, especially while charging, is infinitesimally small these days. The ones that we read about catching fire are almost always off-brands that use cheap, poorly-made batteries.
Lithium Iron Phosphate
Also known as LiFePO4, this is a step up from a sealed lead-acid (SLA) battery. It offers a similar performance to a lithium polymer battery but tends to be heavier.
Lithium Polymer Battery
A type of lithium-ion battery that uses a polymer electrolyte, a semi-solid gel, instead of a liquid electrolyte. These batteries provide higher specific energy than other lithium battery types and are used in applications where weight is a critical feature, like e-bikes and mobile devices. This chemistry is also the most rugged.
Mid-drive motors are mounted at or near the bottom bracket (over the pedals). These have an advantage with a multi-gear drivetrain because riders can control the torque by shifting gears. These are often 250-350 watts instead of higher wattages.
Modes refer to the levels of assist on most e-bikes. Modes are typically referred to as Eco, Standard, High, or Turbo. They may also be numbered, starting at level 1 through to 5 or 9, offering the highest assist.
A Newton meter, often abbreviated as Nm, is a measure of torque. It’s the force of one Newton (the measurement of the force needed to accelerate 1 kilogram of mass at the rate of 1 meter per second squared in the direction of the applied force) applied perpendicularly to the end of a moment arm that is one meter long.
Pedal assist is when an electric motor provides extra power when the e-bike rider pedals. Without moving the pedals, you will get no help from the motor.
A motor’s output power is measured in watts. The number of watts is stated in the nominal amount, not the peak output. A 750-watt motor may put out a 1200-watt peak, but that doesn’t make it more than the legal limit. The legal limit is based on the nominal output of the motor.
The Q-factor is the distance between the pedals measured parallel to the bottom bracket. Until recently, many mid-drive motors had a much wider Q-factor, but modern motors have been shrunk down to have a Q-factor similar to a regular bicycle.
Range is the distance you can travel before using up all the stored energy in your e-bike battery. Many factors are at play that can help you maximize your range. First, you have to factor in the battery’s size, the motor’s wattage, and the mode you’ll be riding in. You also have to add your weight and the bike’s weight. Finally, the surface you ride on, such as the street, dirt, gravel, the grade of hills you’ll climb, and weather conditions will also play a part.
A rear-drive bike has the hub motor located in the rear wheel. While some bikes use a front-drive hub motor, most production e-bikes with hub motors are rear-drive.
Sometimes referred to as “regen,” it refers to direct-drive hub motors capable of recovering a small amount of energy back into the battery while the bike is coasting. When regeneration is active, the motor’s power is cut, and its drag on the wheel increases markedly.
S-pedelec is a European term for what Americans call a Class 3 e-bike, which gives pedal assistance up to 28 mph (45 kph).
Older e-bike batteries used sealed lead-acid (SLA) batteries. These are usually 12 volts, very heavy, and have low capacity. We’ve seen some systems with lead-acid batteries connected in a series to make a 24-volt battery to allow for a faster motor. Electric bikes that use SLA batteries are sold by the millions every year in China, but are rarer here.
Unlike the diamond frame, the step-through frame has either no top tube, or the top tube slopes downward and often parallel to the downtube to make mounting the bike easier. You step through the bike instead of the need to swing your leg over the seat.
This is the percentage of the rider’s pedal input compared to the output of the motor. Eco may be as low as 50-75% support, whereas Turbo can offer up to 350% support.
On bikes with suspension, usually a suspension fork and often with a rear shock, travel refers to the distance the fork or shock will move up or down to absorb bumps or hard landings. Longer travel isn’t always better, as longer-travel forks, such as 150 to 180mm on enduro bikes, have to be beefier and therefore heavier, to handle the leverage on them, so there’s less bump-induced steering. Many commuter bikes will have a suspension fork that can travel 60 to 100mm to soak up bumps at the front of the bike.
The throttle controls motor power on some e-bikes. The throttle is generally incorporated into the right grip of the handlebar but can be a lever next to the grip. The more you turn the grip or press the lever, the more power you get. E-bikes with a throttle are considered Class 2 e-bikes in the U.S. and are legally limited to 20 mph maximum.
Torque is rotational force, whereas power is linear and measured in Newton meters. Think of torque as how much work a motor can do versus power, which is the rate of work that can be done. A motor with a lot of torque can get you moving quickly and make climbing hills easier, whereas the power sustains that speed and helps you maintain speed.
Tubeless tires and wheels have become all the rage for off-road riding, and as the name implies, there is no rubber inner tube to fill with air to keep the tire inflated. Instead, a specially designed rim/tire combo creates its air chamber that stays inflated with a liquid sealant as a superior means to ward off flat tires.
The user interface refers to the parts you use to control the power and modes of your bike. This can include a display, a touchpad, a throttle or pedal assist, and sometimes a smartphone app.
Voltage is the potential force of power flow from the battery to the motor. It’s like water flowing through a hose in that the higher the voltage, the more electrons can flow to the motor so that the motor can do its work. Typical e-bikes use a 36- or 48-volt system.
Walk mode is a really handy feature that makes it easier to hike a bike up a trail that’s too steep or difficult to ride through. It can power the bicycle at a walking pace but doesn’t offer enough power to carry the weight of a relatively heavy bike.
Power is a measure of the rate at which energy flows, and in electricity, it is measured in watts. Watts are the equivalent of miles per hour in the electrical world. They tell you how fast the electrons are speeding down the highway. The higher the wattage, the faster you’ll use the energy stored in the battery.
Watt hours (Wh) are a measurement of overall battery capacity that can be calculated by multiplying the amp hours by the voltage. For example, a battery with a rated voltage of 36 volts and 14 Ah has a capacity of 500 Wh.
Put Your E-Bike Knowledge Into Action
Now you understand the jargon surrounding all things e-bikes related. You have all the information required to safely navigate any road or trail.