Electrifying Power – How Electric Bikes Work
The humble bicycle – a convenient means of transportation that’s been helping folks get around town and nature for hundreds of years. But here’s something you might not know: the electric bicycle is almost as old, with the first patents on them dating back to the 1890s.
While the earliest electric bikes would still be recognizable today, they didn’t take off in popularity until much more recently. Since the 1990s, ebikes have been booming, first in Asia, then Europe, and now even in North America. And as electric bikes have taken off in popularity, they’ve evolved into more interesting and complex machines. So let’s explore exactly how these fantastic contraptions work.
Early electric bicycle patent. Source: Google Patents
Step One, Start with a Bike
To clear up any confusion, let’s start with what an electric bicycle is not: it’s not a motorcycle, it isn’t gas powered, and it doesn’t require a driver’s license. A true ebike has all the basic parts of a standard issue bicycle: pedals, gears, shifters, a chain drive, and of course a bicycle frame (usually steel, aluminum, or if you are a big spender: carbon fiber.)
Now that you have your basic bike, what is it that adds the electricity? Well since you don’t want to be plugging this thing into a wall outlet (that would make your trips rather short!) you need a battery. Typical batteries offer between 250 and 500 watts, meaning they put out around 20 to 50 volts and 10 to 12 amps. To simplify things, think of volts as the potential energy, and amps as how much electricity can flow through any given point. Then, amps multiplied by volts equals watts.
How far a battery will get you of course depends on how much energy your motor uses, as well as the terrain, and how much the cyclist assists with pedaling. On average, a decent electric bike will go about 40 miles if the rider is helping pedal, or just 20 if they’re not. Throw in an “extended range” battery and you may get 60 and 30 miles, respectively.
Older electric bikes usually use lead-acid batteries, which are the type of batteries commonly used to start cars. While they are inexpensive, the downside is that they are very heavy and slow to recharge. More modern ebikes have swapped those for lithium batteries, which are much lighter, require less maintenance, and have greater lifespans.
Now that you have a battery, it has to power something: the bike’s motor. In a more old-fashioned and low-cost setup, the motor is on the rear, with what may be known as a “rear hub” setup. Power flows from the battery to the rear motor, which then directly spins the wheel. This can give the rider the sensation of being “pushed.”
More advanced electric bicycles employ what’s known as a “mid-drive” motor. Here, the motor sits in the middle of the bike, engaging the bike’s drivetrain. This is similar to how a rider would naturally pedal their bike, with the power they generate then being sent along their chain to spin the back wheel. It also means that the motor interacts with your bike’s gearing the same way you would, meaning hill climbs are more efficient for both your legs and your battery if the bike is in a low gear.
Control Your Ride
Another important aspect of an electric bike is the controller. In any electronic device, the controller manages how much power is being delivered to the motor, in essence determining how fast it spins.
For an electric bike, things can be a bit more complicated, depending on the level of assistance the bike model offers. Say you’re feeling like you want to go riding without help, then you can be in “pedal only mode,” where the motor receives zero power, and all the work is being done the old fashioned way, by your legs.
Then imagine you see a big hill up ahead, but you don’t feel like getting too sweaty. Now you might enter “pedal assist mode,” where both you and the motor work together. Depending on how much you work, and how hard you pull on the throttle, the ratio of human and machine power will vary, but either way both your legs and the motor are working together to spin your bike’s back wheel.
Finally, at the end of the ride, let’s say you’ve exhausted yourself. Well now you can kick back and go into “electric only mode.” It doesn’t get any easier than this, as you can even take your feet off the pedals, and let the motor do all the work for you, almost like an electric scooter or moped.
Often, a small device with a display, mounted on the handlebars, will let you choose which mode you want to be in, as well as offer you helpful information about your ride: how far you’ve ridden, how much power you have left, calories burnt, and more.
The best part is, if you know how to ride a bike, you can also easily get going on an electric bicycle. There are no special licenses required, no tests to pass, and no insurance to buy. So if you’re ready to take your biking to the next level, consider taking a ride on an ebike. After all, you’re an expert now!
Oh yeah, if you ever forget any of this, you can consult this handy infographic.
Brought to you by EVELO Electric Bicycles, the maker of amazing bikes for people of all ages and abilities.