The Electric Bike Primer

THE ELECTRIC BIKE PRIMER

It was seven years ago that Electric Bike Action was born and became the first magazine in America dedicated to all things two-wheeled and battery-powered. Not only was the magazine prescient in foreseeing a rapid growth industry spring up, but even years before the magazine debuted, editor Tony Donaldson was helping Lee Iacocca launch his own e-bike. 

This is a Bosch Performance Line CX mid-drive motor.

 

As we all know now, the e-bike industry has come far from those days back in 2001 when Iacocca went public with his bike. In truth, his primitive e-bike was about 15 years ahead of the level of technology that has delivered a solid future that can no longer retreat. 

For anyone new to e-bikes, we’re sure that you have plenty of questions about what to look for. For some, you may want to know what they’re all about and, really, why one might be the perfect addition to your day-to-day. 

WHY DO YOU WANT AN E-BIKE?

Some people want to get an e-bike to get back into biking, some to overcome an injury, still others for a faster commute to work. And e-bikes are the great equalizer, allowing groups of people to ride together easily, despite differences in riding abilities or fitness. No matter how you slice it, anything that gets you on two wheels and outside riding is a great thing!

This is a geared rear hub.

 

START WITH THE CLASS SYSTEM

There are three classes of e-bikes. This was started by the industry to help states make better laws to govern the use of e-bikes. It started in California, but has quickly spread, and now more than half of the states in the U.S. have adopted the three-class system. The classes are as follows: 

Class 1 means any bicycle with a motor that is pedal-assist only (no throttle) that can go up to 20 mph with assistance (you can pedal faster, but you’ll only get assistance from the motor up to 20 mph).

Class 2 can be pedal-assist or throttle at up to 20 mph.

Class 3 can be throttle-assist up to 20 mph and pedal-assist at up to 28 mph. 

Classes 2 and 3 are allowed only on bike lanes and some paved bike paths, but not on bike trails. Class 1 bikes are allowed in all of these places.

A new type of mid-drive, the Fazua Evation motor integrates the battery and motor into one removable unit the size of most systems’ batteries, all fitting into the downtube.

 

DIFFERENT DRIVE TYPES

There are electric-assist bikes in every category. Commuters, hybrids, folding bikes, road, mountain, fat bikes and more. What they all have in common is electric-assist motors, but there are different types of motors to be aware of. 

The first is the hub drive. Usually, this motor is found in the rear wheel, though some bikes  have them in the front wheel. For most e-bikes with hub drives, the motors are rated from 250 to 500 watts. The maximum you can legally use on public roads is 750 watts. There are two types of hub motors—direct drive and geared. The geared ones tend to be quieter. 

“E-bikes are the great equalizer, allowing groups of people to ride together easily, despite differences in riding abilities or fitness.” 

 

The advantage to direct drive is that the motor can incorporate some regeneration, which can help reduce the need for using the brakes, as well as putting power back into the battery when you’re coasting, especially downhill. Don’t expect an appreciable amount of energy to be put back into the battery unless you descend some really long hills. The slight disadvantage to these motors is the drag they put on (called “cogging,” because of the magnets always going across the stator) when the power assistance is not engaged.

Almost all e-bike batteries use these 18650 lithium-ion cells, connected together in both series and parallel to provide plenty of power and range.

 

The other type of motor is called a mid-drive. It is integrated into the bottom bracket area and drives the bike from the middle. This type of motor offers a couple of advantages over a hub drive. First, it centers the weight of the bike. This is very important for mountain bikes. It also takes weight off of the wheels, which allows the suspension to work much more efficiently. Mid-drives also allow a rider to control the torque better using the gears.

For both types of drive systems, the batteries are usually placed either externally on the downtube or inside it. With batteries getting smaller by the day, many bikes (especially road models) rely on the internal location to better disguise the “e” part of the bike.

This is a direct-drive rear hub motor. They tend to be larger and heavier, but the regenerative capabilities are useful.

 

POWER MODES

All e-bikes have different power settings. The lowest one is usually called Eco, and it will generally be just enough to overcome the extra weight of the bike. There are mid-ranges that offer more power the higher the power mode you choose.

For example, Yamaha has four modes on their PWseries motors: Eco+ offers 50 percent of whatever the rider’s leg torque input is. Eco offers 100 percent. Standard offers 190, and High offers 280 percent.

Yamaha splits the difference in size and complexity of the display with this ruggedized unit.

 

Yamaha’s PW-X motor offers a fifth mode—EXPW—that provides 320 percent.

Hub-driven motors usually have numbered power modes instead, which allow riders to control top speed, as well as power. In a class 1 or 2 bike with five different pedal-assist modes, 5 will usually be the most powerful, accelerate the fastest and go to 20 mph. Drop down to level 4 and it will go 18 mph, 3 will go 16 mph, and so on.

SENSORS

All e-bikes have a speed sensor, generally, a magnet bolted to a spoke on the rear wheel, and a wired sensor on the inside of the left chainstay. This will allow the system to control when to add or cut off power to the motor. If that magnet falls off, the controllers are programmed to stop delivering power. Otherwise, your bike would then have no limit as to how fast you can go under power.

This is a custom-made battery from Hi-Power Cycles. Using custom batteries allows for bikes to be built to customer preference for lighter weight, longer range or more power.

 

Some motor systems use a simple cadence sensor. That is, a series of magnets usually integrated into the bottom bracket area and attached to the crankarm or front sprocket that pass over a sensor that lets the controller know when you are pedaling. It doesn’t know how hard you’re pedaling, so you can ghost pedal, or simply pedal a little bit, and the motor will keep going at the fastest speed for the power mode you are in.

This is an external battery mounted on the downtube. It’s semi-integrated. Some batteries sit fully on top of the downtube, while others are mounted either behind the seat tube or on a rear rack.

 

Some bikes also have a torque sensor, which measures how hard you are pedaling, and can add power to assist you based on that. This is our favorite. It feels the most natural and controllable. Some systems, like Bosch, compute wheel speed, cadence and torque 1000 times per second to give optimal power and the best efficiency. 

CHARGING

One thing you want to make sure of if you buy any e-bike is that it comes with a charger. Most are rated at 4 amps, though some come with up to 6 amps charging. There are other options that are even smarter, able to charge faster yet be gentle enough to your battery to keep its life long. An example is the Grin Cycle Satiator, which is a 52-volt, 8-amp universal, programmable fast battery charger that can handle 36–52-volt batteries. You’ll need to get the right cable for it for your battery; altogether, that will cost you a touch over $300.

This is Yamaha’s PW-X II mid-drive motor. Giant uses the name “Sync Drive Pro” for their own branding.

 

Here’s a tip from long-distance e-bike rider Ravi Kempaiah (EBA, December 2019) for getting the longest life out of your battery: “If you don’t need to have the full range of your battery, you are best to charge it only to 80 percent. But, it’s better to charge it to 100 percent if you think you might drain it, as taking a battery to 0 percent one time can be more harmful to the battery than charging it to 100 percent often. Charging to 80 percent most of the time can almost double the lifespan of your battery.”

This is what an internal battery—the type that fits into the downtube—looks like.

FINAL ADVICE

When looking at bikes, we generally suggest getting a known brand name one from a bike shop. The bike shop will assemble it for you and be there for you if you need maintenance. In general, most e-bikes’ motor systems are very robust and can even withstand riding in bad weather, and generally don’t require much, if any, maintenance. But if you do need it, bear in mind that bike shops will often only work on the brands of bikes and motors that they carry for reasons of warranty, liability, inventory and parts.

Last but not least, stay tuned to the pages of EBA for more stories and helpful tips on both the current and future trends of electric bikes. There’s definitely a lot more to come!


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