Regenerative braking is a feature that recharges the battery when the brakes are applied. All Rad Power Bikes ebikes with a direct drive motor have this feature. The RadCity 4, RadCity Step-Thru 3, and RadWagon 3 have a direct drive motor that allows for regenerative braking.
This article explains how regenerative braking works, how it feels to ride a bike with this feature, and more!
How Does Regenerative Braking Work?
Inside the direct drive motor, copper windings are powered by the battery to drive an outer ring of magnets that spin the wheel, which puts the power in your pedal. When either the front or rear brake levers are squeezed (like when coming to a stop or riding downhill), a signal is sent to the motor controller, which changes the motor into a generator, quickly converting some of the momentum of the bike into electricity to charge the battery. Using the direct drive motor as a generator returns some of the energy (that would otherwise be lost) into the battery. This added battery charge extends your riding range!
You can see this in action on your display when the wattage readout displays ~250W. This is actually power flowing back into your battery! You may even notice your battery readout displaying more bars after periods of braking. Check it out if you are able to do so safely while riding-- just remember to only briefly glance down at your display and be sure to stay aware of your surroundings at all times.
What Does Regenerative Braking Feel Like?
Regenerative braking is seamless in the riding experience, and you will likely forget it’s happening at all. Starting from a stop or while using the throttle, you may notice more gentle acceleration from the direct drive motor compared to a bike with a geared hub motor.
As you pick up speed, the motor will give power assistance to the bike, up to the top speed of 20 mph. If you want to ride faster than this, you will need to pedal. At 20 mph, direct drive motors will experience a kind of magnetic rolling resistance (or “drag”) known as counter-electromotive force. This resistance may slow you down a bit when coasting downhill faster than 20 mph, but that doesn't mean it won't still be fun. Applying the brakes will convert this “drag” to energy flowing back into the battery.
Otherwise, a bike that has regenerative braking feels no different than riding any other ebike. Ride Rad!
When is Regenerative Braking Limited?
There are two ways regenerative braking could be limited: if the battery is full or if the brake levers are very tight.
If the battery is fully charged, then power will not flow into battery. This protects your battery by ensuring that regenerative braking does not convert more energy to the battery than it can handle.
If your brake levers are adjusted to be very tight, there's a small chance that the mechanical brakes begin to stop the bike before regenerative braking has a chance to kick in.
You can check if your brakes are too tight by gently squeezing a brake lever while slowly twisting the throttle. When the brake lever stops the power to the throttle, that's the position where the brake lever sends a signal to the controller to stop powering the motor and to begin regenerative braking. If the mechanical brakes stop the bike at this point, you can adjust them using the instructions HERE, so the brakes stop the bike when the brake lever is about halfway between neutral position and the handlebar grip.
When brakes are adjusted properly, ebikes by Rad Power Bikes with direct drive motors use BOTH regenerative braking AND the mechanical brakes to slow you down safely.
Which Models have Regenerative Braking?
Models with a direct drive motor offer regenerative braking. This includes the RadCity 4, RadCity Step-Thru 3, and RadWagon 3. From the outside, these motors are thinner and larger in diameter than the geared hub motors on our other models.
Regenerative braking, which leads to more range in between charges, makes these models efficient, ideal for longer commutes to work, trips to the store, and extended adventures!