Electric bicycles (e-bikes) multiply humans’ natural ability to pedal and balance. What exactly is going on here?
In short, with e-bikes, an onboard electric motor delivers three basic enhancements. Then, at the hands (and feet) of a person, those enhancements create superhuman abilities that transform the bicycle easier to manage and more powerful.
The idea of an e-bike is to add battery-electric power assistance to the drivetrain of a conventional bicycle. This delivers three kinds of enhancements for the operation of a bike:
First, e-bike technology increases the rider’s power output. A typical human pedaling with legs delivers somewhere between 20-200 of watts to a bicycle, at the low end when working gently on flat ground, and on the high side, pushing hard uphill. A battery-electric system stacks 250-1000 watts on top of that, depending on the model and rider’s power selection. The electric assistance means more power going to the bike for a given amount of effort from the human.
Second, e-bikes deliver explosive starting power. In addition to general power assistance, electric motors can immediately put a bicycle into motion in nearly any condition (e.g., under load or on a hill) with little or no effort to the pedaler. This capability is inherent to electric motors and popularly called “instant torque” with electric cars. On a bicycle, it provides explosive launching power that can completely absorb the difficulty and fatigue involved with starts, which can be the most physically-demanding aspect of using a bicycle for transportation.
Third, e-bikes offer the option of throttle-only power. Some e-bikes, specifically, Class 2 e-bikes, carry a handlegrip throttle that delivers exclusive power assistance–in other words, power from the motor alone without pedaling. This feature is similar to the throttle on a motorcycle, but with a low top speed. For most bikes with throttle-only power, assistance will cease when the bike reaches 20 MPH.
So now that we have a performance-enhanced bicycle, how does the extra oomph translate to the work of actually riding?
The answer is that in nearly every aspect requiring physical effort, the bike now gives its rider superhuman abilities.
Those abilities include:
Distance: On an e-bike, a rider can cover 2-3 times the distance using the same amount of physical effort. This “mileage may vary” depending on the terrain, rider, and other factors. But in general, whatever radius the operator of a conventional bike considers a comfortable travel range, it is now significantly larger.
Hills: A rider can choose to erase the challenge of hills to whatever chosen degree, from making the climb of a slope previously thought unmanageable into something comfortable to eliminating the effort needed for one or more hills on a route altogether. While the rider is subject to the constraints of the maximum output of a particular motor and the level of battery charge, in practice they are unlimited by grades designed for motor vehicles and 80% of the trips drivers take in cars.
Load: With essentially zero extra physical exertion, a rider can carry a surprisingly large amount of cargo weight on board (e.g., a standard longtail cargo bike might support 400 lbs), towed in a trailer (additional 100 pounds or so), or both. Such cargo can be nearly anything, from a keg of beer to a Christmas tree to multiple children or even adult passengers. By the same principle, the rider can eliminate the force of headwind.
Ease: Just as power assistance can allow a rider to “do more” with the bicycle, it can also let them do less. Meaning, a bicycle operator can cover the same distance or terrain they did previously on a pedal-only bike, but with less strain. Or more to the point, without sweating. For some riders, this can make riding a bicycle for transportation finally feel compatible with dressing up for work or commuting in hot summer months.
Swiftness: One of the subtly extraordinary benefits of “Instant torque” is the ability to comfortably maneuver environments that require athletic starts, such as a series of uphill stoplights, with almost no physical exertion. In areas with heavy vehicle traffic and frequent intersections, this power can make the the bicycle, already almost impervious to congestion, significantly faster and more enjoyable than traveling by car.
Speed: Electric assistance can bring the top speed of a bike to double or more what an average person can comfortably travel pedaling on their own (i.e., 20 vs 10 MPH). This can translate to the ability–and confidence–to traverse high-stress corridors like narrow bridges where the rider has to mix with cars, or unprotected bike lanes on fast-moving roads, in which the rider feels it necessary to get in and out as quickly as possible.
Balance: With electric bicycles that have throttle assistance, (in other words, Class 2 e-bikes), a rider has new capabilities to safely navigate hazardous conditions such as icy spots by being able to take their feet off the pedals and hold them out for balance while continuing to propel the bike forward.
Together, these abilities transform the conventional pedal-only bicycle into something categorically easier to manage and more powerful.
Stay tuned for additional material with implications and more detail about e-bikes for transportation.
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This document is a working explainer by Ryan Schuchard. Please watch for updates. For questions and feedback, please connect with Ryan through the contact form.
Updated May 13, 2023
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