Why are electric bikes so heavy?

In this post, we will go through all the elements that add to an e-bike's hefty weight and why it can be beneficial to you.

The E-Bike Motor And Battery

In most cases, an electric motor and adds an extra 8kg to a bike. Most electric bike motors weigh between 3 and 4kg, but you will come across heavier ones. These are usually more powerful or not as high quality.

There are two main types of electric bike motor, hub-mounted and mid-mounted. A hub-mounted motor sits in the centre of the rear wheel and turns the wheel directly. These motors are suited to people who are not riding anywhere too technical and for beginner riders.

A mid-mounted motor is located low down in the frame, between the cranks. The motor is connected to your rear wheel via your front chainring. Mid-mounted motors are more efficient, so you will be able to ride further before needing to recharge.

But when it comes to how heavy each motor is, it is not the actual weight you need to consider. What is important when comparing the two motor types is where the weight is positioned.

The position of the mid-mounted motor balances the bike perfectly front to back. This balance gives the bike predictable handling, which is especially important for riding electric mountain bikes on technical terrain. Whereas the weight of a hub-mounted motor sits further back. This isn't a problem for most commuters and leisure riders, but you need to be aware of the imbalance.

But, you need something to power the motor, so this is where the battery comes in. In the past, electric bike manufacturers mainly used lead-acid batteries. Some cheaper electric bikes still use lead-acid batteries, but these are very heavy and not very efficient.

Most modern electric bikes now use lithium-ion batteries. These are much lighter, smaller and hold more charge than the old lead-acid versions. Lithium-ion batteries weigh between 2 and 3.5kg. Still, their weight is determined by their capacity and how the manufacturer has built it.

A battery with a high capacity will weigh much more than one with less capacity. This is worth remembering, as you may want to carry an extra battery in your backpack as a range extender. A big heavy battery on your back will raise your centre of gravity, affecting your ride.

Other Electrical Components

The other electrical components an electric bike needs also contribute to its weight.

For example, to control the motor's power output, you need to use a display. The display acts as a computer and is mounted within easy reach on your handlebars. Its purpose is to allow you to select the different assistance modes and keep an eye on your battery status.

Another component that adds to an electric bike's weight is the controller system. This uses a cadence sensor for a hub-mounted motor or torque sensor for a mid-mounted motor. The control system uses signals from the sensors to determine how much power to call from the motor.

Of course, all these electrical components need to be connected to each other. Therefore, a wiring circuit is threaded through the bike, which adds to the electric bike's weight.

Heavy Duty Tyres

The power and torque from an electric bike's motor are very high; therefore, a standard bike tyre would not cope.

Heavy-duty tyres are essential for electric mountain bikes, as the motor puts more demand on the tyre tread. To counter this, electric bike tyre manufacturers make tyres more resistant to wear. They also perform better on different surfaces while being more resistant to punctures and providing more stopping power under braking.

Electric bike tyres are made with a harder compound to reduce their rolling resistance, increasing their efficiency. All these extra characteristics make electric bike tyres slightly heavier than regular ones.

Beefed Up Frame And Components

Another way electric bike manufacturers design their bikes to cope with the power is to beef everything up. The frame designers need to place the battery and related components in a safe place. But the frame also needs to cope with the weight of the motor and battery system.

Also, in many cases, bike manufacturers need to fit electric bikes with heavy-duty components. For example, the suspension on an electric mountain bike needs to cope with the extra compression from the weight of the motor system. Therefore the tougher suspension increases the weight further, as do the stronger brakes, wheels etc.

How Extra Weight Affects Your Rides

The main attraction of electric bike ownership is how easy it makes getting around. But, where an electric bike really shines is when you need to climb steep hills. You will always ride uphill faster on an electric bike than a regular bike, as the extra power overcomes the bike's extra weight.

If you ride an electric mountain bike, you will notice that the descents are much faster too. The extra weight increases the bike's stability over rough ground, allowing you to ride at high speeds confidently. Also, the low down centre of gravity (with mid-mounted motors) helps with cornering.

When you are just generally riding an electric bike around, the extra weight won't be a problem. However, if you need to carry your electric bike up flights of stairs or load it onto a bike rack, you will undoubtedly notice the weight. Also, if you run the battery flat, you will find riding your dead electric bike difficult, especially up hills.

Final Thoughts

With all the extra components an electric bike has, it is no wonder why they are much heavier than regular bikes. Individually, these more robust components don't weigh much, but their accumulative weight all adds up.

Most of the time, you won't notice the extra weight. Electric bike manufacturers do their best to make their bikes feel as natural as possible. However, depending on your situation, the weight of picking the bike up may make it less practical for you.

As the technology and manufacturing processes improve, there is no doubt that electric bikes will become lighter. This will make the practical issues more manageable while increasing how far you can ride between charges.