Ebikes have come a long way since the first patent for an electric bike was filed in back in 1895. Explosive sales growth worldwide over the last decade is projected to continue and has led to an overwhelming number of ebike options and features. This makes understanding the different components of an ebike the first step in choosing the right configuration.
Starting with the basics, an ebike looks like a regular bike, but with several electrical components added to it including a motor, drivetrain and a battery. There are many different types of components; some are better suited to a retrofit (or electric bike kit) where an ordinary bicycle is converted to an electric bike, while other components require more design integration and are used with production ebikes.
Ebikes have motors that are installed in one of two places, either the center of the frame (mid-drive motors) or on one of the hubs (hub motors). The location of the motor will determine how the bike operates.
Front Hub Motor
This is the simplest and most limited motor installation. They are generally only used with throttle systems, they don’t work well at providing assistance based on rider input (pedaling), and have problems with traction as most of the weight on a bicycle is over the rear wheel. Additionally, cornering while accelerating is difficult when the drive unit is in the front wheel.
Front hub motors are not a popular ebike system and are usually only found on inexpensive electric bike kits as they can easily be added to most normal bicycles.
Rear Hub Motor
Many rear hub motors offer both a throttle and pedelec option and can be retrofitted (as part of an electric bike kit) making them the most popular option for electric conversions. They are limited as they create an uneven weight distribution with the motor in the rear wheel which affects handling, but they are affordable and less noticeable than other motor types.
A mid-drive motor design is activated by pedaling and as such will always be a pedelec. It is an ebike system where the motor is placed in the center of the bike frame and integrated with the cranks and bottom bracket.
It is the best system, delivering more torque than a comparable hub motor and, because it is centrally located, it distributes weight more evenly over the bike. It works well with a bike’s gearing as the motor drives the crank arms, rather than the wheel, and the sensor is better able to measure the amount of input from the rider allowing automatic adjustments to match the speed of pedaling offering a smoother experience.
The mid-drive design is the most popular system for pedal assist production bikes offering many benefits over a hub motor.
The drivetrain provides the power and torque needed to manually turn the wheels of the bicycle. A drivetrain powered by a mid-drive motor receives power directly from the motor which makes chain cranking easier. Most drivechains allow the rider to shift gears (increasing or decreasing resistance).
All ebikes have a rechargeable battery, usually lithium ion, composed of multiple battery cells linked within a larger case. Technology improvements mean that batteries are getting lighter and smaller, but they still contribute most of the weight on an electric bike. Whichever brand of battery you choose, ensure that they have a management system that protects the battery from excessive temperatures, overcharging and deep discharge.
Types of Batteries
The two most popular battery types are rack mounted or down tube.
Rack Mount Battery
A rack mount battery is mounted on the rear of a bicycle and can double as a place for panniers and additional storage. As it is mounted above the rear wheel it can affect handling, making cornering and moving the bike by hand more difficult. It is a flexible system providing a place to fit the battery on almost any bike frame.
Down Tube Battery
The downtube is the most common mounting location for a battery (the tube that goes from the front of the bike down to the crank). This placement puts the battery weight low on the bike which improves handling. It is also a good option in combination with a mid-drive system as the motor is located directly behind the battery. Down tube batteries can be mounted on top of a standard round or oval tube in integrated into an oversized tube.
The battery life depends on many factors including the size of the battery, the bicycle weight, the terrain being covered and the weight of the rider. For newer battery models, expect at least 35 – 40 miles.
The lifetime of a battery depends on how often it is used. Many good manufacturers offer cover for two years, and a good rule of thumb is that they should last around 1000 charge cycles which would be 37 000 miles of riding.
Charging an Ebike Battery
They can be charged from any mains power socket, and most newer models allow for the battery to be removed from the bike making it easier to find a plug point.
A full charge takes between 3 and 4 hours, and most can be partially charged in an hour or two without damaging the battery. Newer batteries do not need to be fully discharged before recharging.
Choosing an Ebike – The Optimal Configuration and Price Point
Typically, a mid-drive motor with a geared drivetrain and down tube battery is the best configuration for an ebike as it has the minimum impact on handling and offers the best performance. This is the most popular combination of good quality production ebikes.
Higher-end ebikes tend to be lighter, offer better battery life and more control over speed, and have better build quality. Ebike tech is developing at a rapid rate, and the latest advances carry a price premium. But in some cases, the price is inflated because of the brand of the ebike.
Prices vary considerably, and for most commuters, a mid-range ebike will be more than adequate. For a mid-range ebike, with good features, by a reputable brand, the price should be around $1500. When choosing an ebike; compare the different features, battery life and build quality of the bike to ensure that you get the best deal.