Electric Bike Performance Explained
When it comes to electric bikes, there’s a lot of information and numbers to gather and understand. For someone who is just getting into electric bikes, or even for those who have experience using them, but don’t understand how the numbers add up, we’ve taken the time and broken down the numbers to some basic, easy to understand infographics below.
When it comes to an eBike’s performance, there are really only a few main components involved. That is, when you’re looking at the main performance specs such as top speed and range. Most other specifications, like braking power, gears, etc., can be rated the same as a standard non-eBike. So when it comes to the top speed and range of an electric bike, the size of the motor and battery are the two main components that dictate these factors.
Electric Bike Top Speed
The Short Answer: VOLTAGE
The max speed of any standard non-electric bike is determined by many factors: weight of the rider, flatness of the terrain, type of terrain (paved, gravel, dirt, etc.), position of rider (upright vs. crouched), width of tires, type of tire grip, size of the wheels, number of gears, and the strength of the rider. We won’t get into these factors since they are more important to standard bikes, whereas the top speed of an electric bike does account for variations of these factors, the main two components for max speed are the size of the motor and battery, specifically the voltage output of the battery and the voltage allowance in the motor. The battery voltage should match that of the motor, so we don’t need to discuss both. In simplest form, the higher the voltage, the faster an eBike will go. The increase in voltage vs. max speed is not a complete linear relationship unless you are in a vacuum with no surface friction. So for real world, practical sake, there is a gradual decrease in the rate of max speed as voltage increases due to wind resistance and surface friction. This car be seen with cars the same way. The top speed of a car will not double if you simply double the horsepower. In fact, it takes exponentially more power to continuously increase the top speed because wind resistance increases so quickly the faster an object moves through air. Of course there is the factor of transmission, or gearing, when it comes to top speed. But for most electric bikes, the gearing is setup to allow for decent low-end and uphill performance and decent top speed. Gearing an eBike for the highest speed possible will cause a reduction in low-end performance, so most eBikes are setup for a happy medium. When it comes to gearing, however, there are three main types of eBike setups: single speed hub motors, geared hub motors, and mid drive motors.
Single Speed Hub Motors: These are the most reliable, longest lasting, and least likely to breakdown. They offer the most performance for their price. These motors are typically placed in the rear wheel and rotate freely from the chain and switching gears on the bike will not affect the performance of the motor. Think of this as a very powerful single speed transmission.
Geared Hub Motors: These are decently reliable, last for a very long time, and do not break down very often. They offer a decent amount of performance for their price, but are usually limited to a medium power output. They are are good option for decent performance for a lower price, or for smaller wheeled bikes such as folding eBikes. You cannot switch gears, but the gears change automatically. Think of this as an automatic transmission.
Mid-Drive Motors: These are the least reliable and the most likely to breakdown. Not only are the motors prone to failure, but more often are issues with broken chains and chains constantly falling off the track. This is because the motor is mounted in the center of the bike on the crank where the pedal axel goes through the frame. This means that the motor actually moves the chain and acts like your legs would when you pedal. This means when you change gears on your eBike you will notice a change in torque or power. This is great for going uphill as you can switch to a low gear as you would in a car, or switch to a higher gear when cruising at a higher speed. This requires a lot more work than hub motors because you typically have to change gears just like you would in a car and the benefits of low and high gears are pretty small and not that noticeable. Think of this as a decently powerful manual transmission.
So what about the numbers? Well, there is some variance based on the numerous factors we previously mentioned (rider weight, terrain, etc.), but here are some typical figures based on voltage*:
24-Volt eBike Max Speed: 15 MPH
36-Volt eBike Max Speed: 20 MPH
48-Volt eBike Max Speed: 25 MPH
60-Volt eBike Max Speed: 30 MPH
*Keep in mind that these may vary 1-3 MPH based on numerous factors. Also keep in mind that 20 MPH is the max speed in most locations, so many eBikes are 36 volts or less. Other eBikes with higher top speeds like many of the Wave Electric Bikes, come with a speed limiter which can be disabled with a toggle switch.
Electric Bike Hill Climbing Ability
The Short Answer: WATTAGE
When it comes to top speed, wind resistance is one of the biggest factors to inhibiting an increased max speed with increased power, but when it comes to hill climbing ability gravity is the biggest factor, which means weight of the eBike + weight of the rider will be the biggest variables aside from the power of the motor. With all things equal (rider wight, eBike weight, terrain type, etc.) the wattage of the motor will determine an eBike’s hill climbing ability. When we talk about hill climbing ability, this is also a similar performance aspect of load carrying endurance and ability. For example, the higher the wattage, the more weight an eBike can load and maintain the same speed compared to an eBike with a lower wattage. The higher the wattage, the steeper a hill an eBike can climb. When we analyze the numbers, we are looking at an eBike’s hill climbing ability with no pedaling and a 160 pound rider.
So what about the numbers? Well, there is some variance based on the numerous factors previously mentioned, but here are some typical figures based on wattage*:
250-Watt eBike Hill Climbing Ability: 6% Incline
350-Watt eBike Hill Climbing Ability: 10% Incline
500-Watt eBike Hill Climbing Ability: 12% Incline
750-Watt eBike Hill Climbing Ability: 16% Incline
1000-Watt eBike Hill Climbing Ability: 18% Incline
*Keep in mind that these may vary 1-2% based on numerous factors. Also keep in mind than 750 watts is the max motor size in most locations, so many eBikes are 750 watts or less.
Electric Bike Range
The Short Answer: AMP HOURS (AH)
When it comes to max range, combine the factors of hill climbing ability (weight) and max speed (wind resistance) and add them together. That’s because range is the most sensitive performance aspect of an eBike. There are more factors that impact range than any other performance aspect and any small change has a much larger effect than the other performance factors. For example, changing an eBike’s speed from 20 to 21 MPH can have a dramatic impact on range, slowing down and speeding up will deteriorate range, rider weight has a massive impact on range, etc. etc. But when all of those factors are equal and we simply want to compare apples to apples, it’s the amp hours (Ah) of an eBike’s battery that has the biggest determination on the eBike’s range. Next would be voltage and then wattage. Think of a battery’s Ah as the amount of fuel in a tank. This is pretty much a linear relationship- any increase in Ah will cause a proportionate increase in range. For example, if you double the Ah of an eBike battery from 5Ah to 10Ah, the range will typically double. Why do voltage and wattage matter? Because the less work the motor has to do, the slower the drain on the battery. Think about it like this, if you have one eBike with a huge motor that only needs to output 20% of its potential power to go 20 MPH, whereas another eBike with a smaller motor needs to output 50% of its power to go 20 MPH, the eBike with the smaller motor will drain the battery a lot more quickly. Also, as previously mentioend, the more consistent the speed of the eBike, the better the range. Think of this example, if you are constantly stepping on the gas and speeding excessively in a car, you’re going to get horrible fuel consumption (MPG) and run out of fuel a lot sooner than if you were cruising at a steady 55 MPH on the freeway. Our analyses are based on eBikes with throttle-only options (no pedaling) and a 160 lb rider. Be careful when browsing electric bike specs that you examine their advertised range of full electric vs. pedal-assist mode. Many companies will primarily advertise their pedal-assist specs, which is very deceiving because this depends hugely on the strength of the rider. An apples to apples comparison is to look at full electric mode specs with no pedaling.
So what about the numbers? Well, there is some variance based of the numerous factors previously mentioned, but here are some typical figures with no pedaling involved based on Ah*:
36V 350W Motor + 10Ah Battery: 18 Miles
36V 350W Motor + 20Ah Battery: 36 Miles
36V 500W Motor + 10Ah Battery: 19 Miles
36V 500W Motor + 20Ah Battery: 38 Miles
48V 500W Motor + 10Ah Battery: 21 Miles
48V 500W Motor + 20Ah Battery: 42 Miles
48V 750W Motor + 10Ah Battery: 23 Miles
48V 750W Motor + 20Ah Battery: 46 Miles
*Keep in mind that these may vary 5% based on numerous factors.