Is there anything different about the brakes on an eBike? Heck yeah! If you look at the brake lever assembly at your hands, you’ll notice two sets of lines running from each lever assembly. That’s a unique feature to electric bikes.
In this article, I’m going to describe how the whole braking system works in harmony on your eBike to bring you safely down from the high speeds that having “the power” provides.
The Bike Braking Physics
All bike brakes work by using a controlled system that transforms kinetic energy, which is the energy your bike has when it’s moving (rolling), into heat.
This transformation happens when you apply the brakes and the friction between the brake pads and the wheel rim or disc brake rotor generates heat. This process of creating heat slows down and eventually stops your bike. Simple, right? 🤯🤯🤯
Let’s Start with the Different eBike Braking Systems
Rim brakes are the traditional brakes seen on many lower-priced bikes. The assembly uses a caliper or a “V-Brake” to squeeze the tire rim, converting your forward motion into heat, thereby slowing the bike down.
A properly tuned V-brake system can work really well, but the key is to keep it in good working order. On an electric bike, as the brake lever is squeezed, a switch is triggered, which cuts power to the motor.
Disc brake systems come in two versions: mechanical and hydraulic. Both versions have calipers that clamp down onto a rotor disc mounted to the bike wheel hub. Disc brakes are preferred for most electric bikes for their durability and modulation control.
Mechanical disc brakes use a cable to actuate the caliper. As you squeeze the brake lever, a cable is pulled that clamps down onto one side of the disc. Just like on the rim brakes, a switch is triggered in the brake lever assembly that sends a signal to the bike’s controller.
Hydraulic disc brakes use a fluid instead of a cable to transfer force to the caliper to squeeze the rotor disc. The lever assembly has a reservoir of fluid, usually mineral oil, and the squeezing action pumps the fluid into a hose which in turn pushes on cylinders in the caliper which pinches the rotor disc.
In a hydraulic disc brake system, a switch is triggered in the lever assembly as soon as movement is detected. The signal from the trigger is sent to the controller and power is cut to the motor.
Regenerative brakes are only found on direct-drive hub motors and work in combination with disc brakes. Basically, regen brakes convert the kinetic energy back into electricity. So, instead of a motor mounted in the wheels, you have a generator. When that switch in the brake lever is actuated, it REVERSES the flow of electricity. The result is the motor slowing the bike and charging the bike’s battery.
Diagram of an Electric Bike Braking System
Electric bikes have two systems, one for the braking and a second system that cuts power to the motor.
Factors That Affect Stopping Your Bike
A bunch of things can affect your ebikes braking. The key considerations are below:
Your Load and Speed
Let’s jump back to the physics – converting kinetic energy into heat. Faster speeds and weight in motion add energy, and your brakes convert that energy into heat at a set rate (TIME). As an e-bike rider, you’ll quickly notice that your weight and any extra stuff you’re carrying can really affect your brakes. The heavier the load, the harder your brakes have to work to slow you down. And remember, e-bikes are already heavier than regular bikes because of the motor and battery.
Riding on Different Terrains
The type of ground you’re riding on can make a big difference to your brakes. Don’t be surprised that it takes twice the distance to stop your eBike going downhill as compared to a traditional bike.
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Choosing Your Brakes
The kind of brakes on your e-bike can affect how well they work. Hydraulic disc brakes are really strong and good in the wet, while mechanical disc brakes still squeeze on a disc, the amount of force applied is through a weaker cable system.
Rim brakes can work well, but a wobbly rim or poorly adjusted cable is going to reduce how effective rim brakes stop. Rim brakes need regular attention and maintenance.
Regenerative brakes can even help stop your bike and charge your battery at the same time, but how well they work can depend on a few things, like the percentage of regen set in the controller.
Keeping Up with Maintenance
Alright, let’s talk about keeping those e-bike brakes in tip-top shape! As a seasoned bike mechanic, I can’t stress enough how important regular maintenance is for your brakes.
First off, you gotta keep an eye on your brake pads. Over time, they can wear down, which can make your brakes less effective. So, make it a habit to check your brake pads regularly. If they are looking a bit thin or worn out, it’s time for a replacement.
The added weight from the motor and battery accelerates how quickly your brakes pads wear out.
Another way to understand disc brake pad wear is by looking at how close the brake lever comes to the handlebar. You should have 2 fingers of distance from the lever to the bar. If the lever gets closer consider brake pads or bleeding the brakes.
Wrapping it Up and Slowing Us Down
Alright, that’s a wrap on our deep dive into e-bike brakes! As we’ve seen, there’s a lot more to these systems than meets the eye. From the traditional rim brakes to the high-tech regenerative ones, each type has its own unique features and quirks.
And remember, no matter what kind of brakes you have on your e-bike, keeping them in good shape is key. Regular check-ups and maintenance can make a world of difference in how well your brakes work and how safe you feel on the road. So, here’s to safe and happy e-biking!