Electric motors translate electrical energy into mechanical power to boost your pedaling effort. They’re not just for lazy people, but can make cycling fun on even the steepest hills and longest rides. You can control the amount of power you receive via a button mounted on the handlebars, and some systems let you switch between modes that adjust the amount of pedaling assistance to match your terrain and style.
There are two different types of e-bike motors: hub or crank. Hub motors sit in the wheel hub and are usually quieter than crank drive systems. The most common are geared hub motors, which use a system of internal gears to turn the shell of the motor and generate more torque at lower speeds than direct drive units. They’re typically cheaper than mid drive motors too.
More recently, the market has been dominated by mid drive systems that use a belt to spin a cog on the motor’s shaft and create more powerful, more linear output at higher speeds. These motors can be more expensive than hub systems, but are quieter and offer more consistent power at all speeds, which is useful when climbing or cruising on flat terrain.
The amount of power an e-bike uses and how long it lasts depends on the motor’s wattage and how much voltage, or amp-hours it draws from its battery. These figures determine how quickly it can accelerate and the range a bike will achieve. If you’re planning to use your e-bike for long commutes or hilly rides, then a more powerful motor and larger battery are recommended.
Most e-bike systems offer a choice of battery capacity, and you can also upgrade the size of your frame battery to extend your ride range. Bike batteries have shrunk in size and become lighter since switching from lead to lithium cores, but they still add weight to your setup. The location of the battery can also influence the handling and balance of your bicycle, so look for a pack that’s well-balanced, positioned low and centered on the frame.
There’s a huge selection of options out there when it comes to buying an e-bike, but not all systems are compatible with all frames. For example, mid drive systems are often designed to work with a specific frame supplier’s motor and battery, so it can be tricky to swap between systems.
Some companies, such as Bosch, offer all-in-one systems that include the motor, battery and sensors in a single unit. These are among the easiest ways to convert a standard bike into an electric bike, and they’re often the best option for riders who plan to commute or do frequent hilly rides. The company’s 2023 e-bike offering, the Bosch Elevate all-in-one system, is a good example and is available in a 350W version that peaks at pedal-assist mode and can be run on the flat, climb or Eco modes. It can be paired with either a front or rear rack, and is compatible with internal and external frame mounting.