eBike Types - Pros and Cons
Broadly speaking there are 2 types of eBike drive systems available and when deciding which style to go for, one of the most important factors to consider is the type, and degree of control you want over the motor. Pedal assisted electric bikes provide a similar riding experience to a traditional bike, only your pedaling power will be supplemented by the electric motor where as throttle power closely resembles a motorcycle or moped. Most modern and higher end e-bikes will have both pedal assist and throttle options and typically riders get a longer range out of their battery when using pedal assist as the demands placed on the motor are lower.
PAS systems detect and respond to your pedaling. When the bike is being used, the automatic motor detects movement and force applied to the petals and adjusts to provide adequate help to the rider. The motor can only be activated through pedaling and is limited to relatively low speeds. Pedal assist systems will have different levels of assistance which are generally percentages of total motor output for example, if an electric bike has 5 PAS settings, level 1 will be 20%, level 2 will be 40% and so on. There are two styles of pedal assist systems:
Cadence sensors use magnets on the crank of the bike to detect movement and tell the motor when to turn on and off. The speed that the magnets pass the sensor determines how fast the motor will go. A sensor will detect how fast you’re pedalling and allows the motor to kick in and assist you to reach whatever level of speed you have set. Cadence sensors only begin to operate once you’ve started pedalling for a few seconds. The benefit of these systems are that they are basic and inexpensive. Cadence systems can feel jerky and laggy when ridden however. The crankset usually needs to be rotated 2-3 times before the motor can kick in, making it far from ideal if you are at traffic lights or climbing a hill particularly if you are riding in a high gear when you come to a stop. Cadence systems can work counterintuitively at times because they operate based on how fast you are pedaling. If you are going on a flat surface, faster pedaling speed means more power is needed but when climbing a hill when the resistance is greater and you require more assistance, your pedal rotation speed will be lower meaning you will be provided with less power than you may require.
Torque sensing systems feel natural, like riding a push bike because the power that you apply to the pedals is directly proportional to the amount of power the motor will put out. These systems require little effort to operate because of the system that will automatically kick in once you start moving the pedals. This style senses how hard you are pedaling by measuring the pressure applied to the chain and more accurately adjusts to the speed that you require than cadence systems. This system can assist immediately once pressure is applied to the pedals because you can generate a lot of power from a standing start. This type of system is more complex than the example above as it monitors 3 factors: pedal rotation, force and road speed, and adjusts on-the-go. There is a certain amount of pressure that must be applied in order for the motor to kick into motion which changes from bike to bike, the ride is a great deal smoother though.
As torque sensing systems are more complex than cadence sensors, they are more costly to add to a bike. Electric bikes at the lower end of the price spectrum will generally have cadence sensors, and if you are investing in an e-bike for regular use, the style of PAS system is definitely worth checking out to ensure you get the right system for your needs.
This style features a variable throttle switch on the handlebar similar to a motorcycle or moped to manually turn the motor on or off and to control the motor’s output. Using a throttle lever allows the rider to take more control in turning on/off the bike and to control how much power/battery is used making it very easy to ride in either pedal-only or motor-only mode. The main drawback of riding using a throttle is that the battery will get eaten up a lot faster than when using a pedal assist system. In Europe, electric bikes are restricted to pedal assist only. In the US on the other hand, throttle controllers are legal and highly popular and many ebikes offer both options. Throttles provides the rider with full motor power instantly and allows for complete control. Where some pedal assist systems need to be moving above a certain speed before they kick in, using a throttle can help a rider get started from a standstill, get a burst of speed to help you up a hill or through an intersection.
Throttles can come in three forms, half twist, full twist and thumb controlled. Riders who have ridden motorcycles and scooters often find full twist throttles easier and more comfortable to use however, they can be particularly dangerous. For instance if the user is not used to having a twist throttle on their handlebars, lifting the bike up to an apartment, over obstacles or curbs can be dangerous as it is easy to slip your hand over the throttle and accidently engaging it while lifting, causing the bike to accelerate and potentially lose control. The jury is out as to which is the best throttle method, each have their pros and cons. Twist systems can be a little safer when it comes to emergency situations as your entire hand is in contact with the handlebar, providing more control when maneuvering. Half twist systems often result in less hand/wrist fatigue than the other two types on longer rides because you can keep 2-3 fingers on the handlebar while engaging the throttle, this gripping arrangement allows you to keep pressure on the throttle naturally rather than flexing your wrist or extending your thumb.
Both is best
E-bikes with both drive systems are most popular as they offer the rider an option at least. Often experienced cyclists who still want the feeling of pedaling prefer pedal assist systems but there will be times that using a throttle will be necessary. Pedaling uphill on an ebike can be tough due to the added weight of the battery, motor and heavier duty materials. Pedal assist can be seen as a type of cruise control, particularly when on long and flat journeys. It allows you to relax and just complete a pedaling motion without exerting too much effort and you won’t have to worry about holding a throttle in place. The higher price of e-bikes with both systems reflects the complexity of adding both PAS and throttle components to the bike but will enhance the user’s experience because of the choice offered to them.
To learn more, see our electric bike motors tutorial.