Whoever thought to add an electric motor to a bicycle deserves a prize for such an innovation. Electric bikes are a popular commuter tool and way for anyone to get outside into fresh air. While these bikes overcome many of the problems inherent with standard bikes, especially people tiring too soon, they do come with the problem of having to navigate the terms used for their electric components to make the best selection.
If you want to purchase an electric bike of your own, you need to understand wattage, voltage and amp-hours and what they mean for your ride to make the best decision for your lifestyle. Here, you will find electric bikes explained with the definitions and more about their operation.
Electric bikes use a motor to assist the movement of the pedals, making riding the bicycle less taxing. Some designs allow the bike to move forward under its own power from the motor while electric pedal bikes require some assistance.
Don't confuse electric bicycles with motorcycles. The electric motor and battery don't last as long as a gasoline-powered engine. However, e-bikes are better for the planet because they do not generate polluting exhaust when you ride them. They also are a healthier option for you because you will have to use your power to move the bike, which will improve your cardiovascular fitness.
While you might think electric bikes don't have an upper limit for their speed, thanks to the addition of a motor, they do. Because federal regulations under the 2002 Consumer Product Safety Act regulate the definition of low-speed electric bikes, you will have a speed limit for how fast you can go with motor assistance. Depending on the bike you have, you may have a speed limit of 20 to 28 miles per hour (mph).
E-bikes have three classes in states that define what an electric bicycle is. Check with your state laws because some places regulate the operation of certain e-bike classes to specific age groups.
These bikes assist the rider while they pedal at speeds up to 20 mph.
These bicycles may use a motor only to propel the bike up to speeds of 20 mph.
The fastest bikes only provide motorized assistance when the rider pedals, up to 28 mph.
Electric bikes have three main components that set them apart from standard bicycles — the battery, the motor with its controller and the sensor.
The battery powers the motor. This device's capability for generating power and how long it lasts are where the numbers for wattage, voltage and amp-hours come into play. To keep these weighty parts of the bike from upsetting your balance, they have a position low and centered on the bicycle.
While bike batteries have shrunk in size and increased in power since converting from lead-acid to lithium cores, they still contribute a significant amount of weight to your bike.
To prevent electric bikes from going too fast, they have sensors that monitor your speed to determine when to instruct the motor to turn the throttle or pedal assist on or off. The sensors may measure speed or torque. Both act in similar ways, though. The speed sensor watches how fast you travel. A torque sensor, however, monitors how hard you pedal, as harder pedaling correlates to faster speeds.
Electric bikes use a motor to boost your ability to ride. If you tire out while riding an e-bike, you can use the throttle to help you move. Pedal-assist also kick in while you pedal the bike, allowing you to use less effort. As soon as you stop pedaling or go over the preset speed limit of the bike, though, the pedal-assist stops.
The motor changes electric power into mechanical work that it uses to help turn the bicycle's wheels. Manufacturers have three positions for placing the motor — the front hub, rear hub and in the center of the bike. Motors placed on the front hub have become less popular today than those installed in other locations on the bike. You will typically find these front-installed motors on low-end e-bikes.
Rear-hub motors drive the bike from the rear wheel and integrate with the bicycle gears. The motor in this position improves traction and handling thanks to its connection to the gearing. With better control, rear hub motors often appear on mid-class e-bikes.
Premium, and very expensive, electric bikes have their motors near the center of gravity and attached to the frame. This motor position does not prevent you from quickly changing tires on your bike while making the bike stable.
E-bikes are typically made with electronic components that have secure coverings with tight seals to prevent damage from light rain. They can withstand a variety of climates, but it's important to use common sense and avoid overexposing an e-bike to significant water and/or rain.
Now that you know about the parts that set an e-bike apart from a regular bicycle, learn more about the power options and what they mean.
The wattage is one aspect of your bike's battery power. Along with voltage and amp-hours, the wattage informs you about the potential speed and performance of your bike. Understanding the differences between wattage and watt-hours will also help you to see how long you can ride your bike before you need to recharge it.
Wattage refers to the power output of a motor. You will see wattage listed with the motor power as both peak and nominal power. These ratings measure the ideal calculated value and typical operating capability of the motor, respectively.
Peak power indicates ideal power from the motor under full throttle and ideal operating conditions. Your motor will likely never reach this value because some power gets lost through friction and other means.
To give you an idea of the realistic amount of power you will get from the motor, manufacturers list the nominal wattage. At the highest power levels, the nominal wattage will typically be 75% of the peak operating power. This value is the second number you see listed with motor power and reflects actual usage. Use this number when calculating watt-hours.
Watt-hours tell you how long your bike can last with its specific motor before you need a recharge and will also dictate the top speeds your e-bike is capable of going.
The motor power wattage helps you to calculate the watt-hours for your bike. Motors with higher watts will require a longer-lasting battery to support the extra power.
Watts come from the product of the battery's voltage and the motor controller's amps. For example, a bike with a 52-volt battery and 20-amp controller will produce an ideal wattage of 1,040 watts.
52 volts x 20 amps = 1,040 watts calculated power
Find the nominal motor wattage by multiplying this value by 0.75 or 75%.
1,040 x 0.75 = 780 watts nominal power
You calculate watt-hours by multiplying the battery's voltage by its amp-hours. For instance, a 52-volt battery with 13 amp-hours will produce 676 watt-hours of power.
52 volts x 13 amp-hours = 676 watt-hours
To use this information to calculate how long your bike's battery can last at full throttle, divide the watt-hours by the nominal motor wattage. For the above example, divide 676 watt-hours by 780 nominal watts.
676 ÷ 780 = 0.867 hours
Multiply this value by 60 to find out how many minutes the battery will last.
0.867 hours x 60 minutes = 52 minutes
This value reflects running the bike at full throttle continuously. You can save battery life by pedaling more and using the motor less frequently. There are a lot of other factors that affect riding range and battery life, including total payload, average speed, tire pressure, and much more. Ideally, e-bikes supplement your biking skills rather than take them over.
The voltage for your electric bike will depend on the bike's battery. Lithium batteries offer much higher voltages compared to their older lead-acid counterparts.
Voltage measures how much power the battery can send to your bike's motor. Higher voltage means more power can flow from the battery to the motor in less time, boosting performance. Combined with amp-hours, the voltage gives you an idea of the battery's watt potential.
You will see the voltage listed with the battery. Batteries for premium bikes might be 48 or 52 volts. Even if you have a lower voltage required for your bike, you can still use a higher voltage battery to boost the performance. Most bike motors will allow for a specific amount of voltage overage before they break down.
For some bikes, such as those from us at Juiced Bikes, the motors are backward compatible with some lower voltage batteries. For instance, you can use either a 48-volt battery or a 52-volt model on the RipCurrent S bike. Other bike brands do not offer this capability to use lower voltage batteries with higher voltage bikes.
Currently, 52 volts is the highest amount for electric bike batteries. Higher voltages likely won't appear on existing electric bike models as it would tip the voltage into the high-voltage range, which would require much stricter regulations.
Every bike in the Juiced portfolio includes the industry leading 52 volt battery.
E-bikes will have a voltage range you must stay within when selecting your battery. Choosing a higher battery voltage can improve the performance of your bike.
Higher voltage batteries operate more efficiently, which explains why they can boost your bike's performance. These higher voltage batteries need less current while supplying the same amount of power as lower-voltage batteries. Since they need to work less, they have greater efficiency and a much longer battery range.
Higher voltage batteries will help your bike get the extra push it needs to climb hills or move more massive people or cargo. It does this by getting the electricity from the battery to the motor faster compared to lower voltage batteries.
If you need to know about your battery's capacity, look for its amp-hours. Related to the amps measurement, the amp-hours give you a clear idea of how long your battery will last.
Amps measure the output of your battery. Amp-hours indicate the capacity of your battery by noting how much electricity your battery can put out in an hour at top voltage. The higher the amp-hours, the longer your bike can run, generally.
Amp-hours for your bike's battery give you an idea of how long the battery will run before it needs a charge. For example, if you have a 20 amp-hour battery, it will last for 20 hours providing one amp of power. Should your motor draw more energy, it will last less time. At two amps per hour, the battery will last for 10 hours.
Think of amp-hours as the gas tank with amps as gas. Higher amp-hours will last longer with similar bike use and energy draw.
The amp-hours and battery voltage are both essential factors in finding out how long you can ride your electric bicycle on a single charge. As noted, the product of these gives you the watt-hours.
Because amp-hours act like a gas tank, amps as gas and volts as gas flow, these parameters help you to see how long a charge will last at maximum capacity, which gives you watt-hours. Without knowing amps or amp-hours for your bicycle's battery, you would find comparing models complicated. Amps also help you to find the best charger for your ride.
You will see amps listed with the battery and the charger. Higher amps on the charger will recharge your bike much faster. The amps listed for the charger indicate how many amps the charger will move per hour into the battery.
For example, a standard two-amp charger adds two amps of power back to the battery each hour. It would take 5.2 hours to recharge a 13 amp battery from 10% to 90%. If you replaced the standard charger for an ultra-fast model that moves seven amps per hour, the charging time drops to 1.5 hours.
Watts, volts and amp-hours all play roles in the quality and longevity of your e-bike. However, you also have to know the construction of your bike will live up to high values for these statistics. Look for trusted names in electric bikes, like Juiced Bikes. We build high-quality, high-performance rides for the daily commuter, fitness enthusiast, casual rider and weekend off-road warrior.
Have you decided you need an e-bike to ease your commute or make riding more fun? Explore our high-performance electric bicycle options at Juiced Bikes. We specialize in giving you the ultimate thrill when riding, which is why we don't hold back when it comes to adding features. Our philosophy for bikes is "more features, more fun." We think you'll agree when you choose one of our ready-to-ride e-bikes. Biking will never be the same for you.
When someone hears electric bicycle, the first image they imagine may be a scooter or electric motorcycle - but they actually look pretty different. Just picture a regular bicycle, then add several electrical components to it like a motor, a battery, and a controller – all seamlessly integrated into the design. These items make up the fundamentals of all electric bicycles on the market!
Electric bikes pedal and handle just like a regular bicycle. By and large, an electric bike will use the same parts too. The electric component is meant to augment human power, not completely replace it. It makes obstacles like hills and headwind more manageable and allows you to travel further without getting as tired.
See our diagram for a more detailed look at how electric bikes work including the motor, battery, drivetrain, and charging process:
Comfort and quality of the components are still as important on an electric bike as they are on a regular bicycle. But now, there are a few more things you need to consider.
Electric bike motors come in a wide variety of power ratings, from 200W to 1,000W or more. The legal limit in the US is 750W, although different states can set their own limits.
Think of this limit kind of like horsepower. A higher rating means that the bike will be able to pull more weight with greater ease – but at the expense of using more battery capacity while doing so. Consequently, a 750W motor will drain the battery much quicker than a 250W one, but it will be more powerful.
One more factor needs to be considered, however. The design and location of the motor plays an important role in how electric bikes work.
The most common type of motor for electric bikes is called a hub motor. It is generally integrated into the rear or front wheel. When engaged, it pulls or pushes the wheel along. Although this system works well, it has one key disadvantage. Since it is not connected to the bike’s gears, it loses efficiency on hills and varied terrain. Imagine driving a vehicle in just one gear the entire day. It will get you places, but it won’t give you the optimum amount of torque or speed that you get with a full gear range.
At EVELO, we offer a patented mid-drive motor, which is integrated with the crank and the gears. This adds several advantages:
Increased performance while spending less battery energy, since the mid-drive motor uses the bike’s existing gears;
Much better hill climbing power, since you can switch gears depending on the incline; and
Handling is improved, since the motor is positioned closer to the ground, keeping the weight centered and low.
Since the battery affects the weight, style, and range of the bike, its choice is crucial. Batteries play a huge part in how electric bikes work. The majority of the batteries you’ll find offered on the market fall into one of the following two categories:
These batteries were once the standard battery type for most electric scooters and electric bicycles. These days, most electric scooters still use SLA batteries, while electric bikes (which often require human input) have opted for newer battery technologies to keep the bike as lightweight as possible.
Inexpensive
Heavy and bulky
Offer a shorter riding range
Shorter life span of about 100-300 full cycle charges
Require more maintenance, and need to be charged immediately after use
These are the newest technology in batteries. A lithium battery has a lifetime roughly 2-3 times that of an SLA battery. Lithium batteries are much lighter and also are largely maintenance-free.
Lightweight – high-capacity, 36V10Ah Lithium-Polymer batteries can weigh as little as 6 pounds!
Offer a longer riding range – battery can travel up to 40 miles in pedal-assist mode (or 20 miles on throttle-only).
Longer life span of about 800 charges or 3 years of virtually daily use
More expensive – starting at about $1,500 to $3,000 and above
Available in a variety of styles, the controller lets you operate the electric assistance on your electric bike and is an important part in how electric bikes work. The controller is located on the handlebar for ease of use. There are two main styles of controllers – pedal-activated and throttle-based controllers.
Pedal-activated systems offer electric assistance as you press down on the pedals. There is no need to engage a throttle – simple pedaling will do the trick. Electric bikes with pedal-activated systems have a controller mounted on the handlebar that lets you adjust the level of assistance that you receive as you pedal. You can dial in the amount of assistance you want, ranging from no assistance to a great deal of assistance.
Throttle-based controllers work with a simple throttle mechanism. The throttle will either be a twist-grip type or a thumb-press type. With a throttle, you simply pull back or press the throttle to receive the electric assistance. Some electric bikes require nothing more than activating the throttle, allowing you to ride without pedaling.
By and large, electric bikes are simple to use, ride, and maintain. Overall, they require little maintenance beyond that which a standard bike requires.
Electric bicycles are designed to be very easy to operate. As a rider, you have three modes of operation available to you:
At any time, you can pedal an electric bicycle just as you would with a regular one. There is no extra resistance created by the motor, so it will feel exactly as a regular bicycle would. Depending on the model you purchase, your bicycle will come either with a 3 gears or 8 gears or a special NuVinci® N360™ internal drivetrain that provides you with unlimited gears.
In this mode, you can take advantage of combined human plus electric power. Once you turn on this mode via the on/off button on the handlebars, the motor will gently provide electric power as you pedal. You can still switch gears as the terrain changes to take advantage of more torque or faster speed. It’s an amazing feeling to use pedal-assist mode, as it makes cycling effortless, flattens out the hills, and frees you to just enjoy yourself and the scenery.
Pedal-assist mode provides three levels of assistance: Low (30%), Medium (60%) and High (100%). The percentage simply indicates how much additional power the motor will provide to complement your pedaling. The low setting adds an additional 30% of power to your pedaling, while High essentially doubles it. A simple press of a button switches you through the different levels.
This mode of operation allows you to sit back and take a break, as you let the motor do the work. To use “electric only” mode, simply twist the throttle located on the left handlebar and you’ll feel the motor kick in and propel you forward. Keep the throttle turned to continue along or let go if you’re ready to start pedaling or wish to come to a stop. Please note that due to Federal regulations, the top speed in electric-only mode is limited to 20 miles per hour.
Electric bikes are still a fairly new concept in the US, so there is a lot of confusion about how the law views them. Federal law considers electric bicycles in the class as regular bicycles, provided they meet two conditions: (1) the top speed in “electric only” mode is 20 miles per hour; and (2) the motor power must be no more than 750W.
EVELO electric bicycles meet both of the federal requirements. We cap the top speed in “electric only” mode at 20 miles per hour, although you can of course go faster on your bike with pedal power if you wish. Our motors are rated at 250W, which is well within federal limits.
Consequently, electric bikes do not need a special registration, license, or insurance to operate. Moreover, they enjoy the same privileges as regular bicycles, such as being allowed to travel in available bike lanes.
However, different states have their own special requirements regarding electric bike use. While most follow the federal lead, some do vary. If you have questions about how electric bikes work in your state, you can get in touch with us and we’ll point you in the direction to find out additional information for your state. For your own personal safety, we recommend helmet use and lights and reflecting gear, even if the law does not specifically require them.