So, you are wondering what an eBike shift sensor is and whether you should add one to your eBike. A shift sensor is a great addition to your eBike and designed to add longevity to your cycle. Continue reading to learn more about why these little sensors are a great buy!
What is an eBike Shift Sensor?
A small experimental device appeared on the market from a Czech company. They were attempting to perfect functionality for mid-drive eBikes. This was achieved by putting a small device on the shifting cable by cutting a small section of the shifting cable off and rerouting it through this device. As the gears shifted, the motor power was cut off, smoothly and efficiently, allowing the drivetrain more longevity. This device is called a gear shift sensor.
An eBike shift sensor is used to protect the drivetrain and mid-drive motor. An average cyclist puts out approximately 150 watts of human power. Most drivetrains can handle slightly more than that.
However, now we add between 450 and 750 watts from the mid-drive motor, close to 3 to 6 additional cyclists each with 150 watts of human power, and we have exceeded the capabilities of the drivetrain. The drivetrain moves the chain across numerous cogs with a few teeth on one of the gears. This is where a gear sensor comes in handy.
How Do Shift Sensors Work on an eBike?
When installed on an eBike, a gear sensor can detect the movement of the cable as the eBike shifts. This sensor stops the motor for approximately a quarter of a second. Some mid-drive motors have a gear sensor cable already installed on the motor control module, so they are ready to equip a gear sensor.
If your motor lacks this cable, the gear sensor can be added to the brake sensor cable instead. When added to the brake sensor, though, the motor will shut off for at least 2 full seconds, which can be a hindrance to the rider.
RIDEeMTB Pro Tip: If you have brake sensors installed on your eBike, you can “simulate” a shift sensor by lightly appling the brake (which cuts power) and then shifting gears. Read more about brake sensors in this article 👉 What are eBike Brake Sensors and How Do They Work?
Can I Add a Shift Sensor to an eBike?
Yes, you can. Installation of a gear shift sensor on an eBike is straightforward. Frist, you need to choose the position of the shifting cable. Place the shift sensor on the straightest part of the shifting cable. Ensure the sensor will not receive direct splash back from water or mud. Next, cut the length of the outer casing, around 2 inches, of the cable and put cap ends on both.
Next, push the inner cable into the plastic housing to fit the direction of the input. When pushing the cable inside the housing, keep the cable parallel to avoid bending and damaging the exposed cable wire. Push the exposed cable through the sensor until it comes out the other side. Adjust the shifting system properly and connect the sensor to the drive unit.
The following manual shows one brand of gear shift sensor and how to properly install it on an eBike: https://www.electricbike.com/manuals/gearsensor-manual.html
RIDE e MTB Pro Tip: With eBikes growing in popularity learning all the terms and definitions can be a bit overwhelming. Let me help with this comprehensive glossary. 👉 eBike Glossary
What Types of Motors Do Gear Shift Sensors Work With?
If your eBike features a read derailleur with a mid-drive motor, you will want a gear shift sensor. You must pedal this type of motor through the shift, meaning the motor stays on the whole time you shift. If you are between mid-level and high-level motor assistance, you can put between 450 and 1000 watts on the drivetrain. The gear shift sensor is critical in this situation to keep the drivetrain at or below the safe wattage.
Some motors do not require a gear sensor. For example, a hub motor does not use the drivetrain; therefore, you do not need a sensor to relieve the additional pressure placed upon the drivetrain.
If your eBike features an internal gear hub, like some 3- or 5-speed eBikes, you likely do not need a gear sensor. This is because you must stop pedaling to shift, which causes the motor to stop anyway. When you begin pedaling again, the motor reengages.
It is worth mentioning that some motors have a slight pause when you stop pedaling before the motor disengages. Wait until it completely disengages to shift. Some models are programed to cut off instantaneously, which negates this issue.
If your eBike has a torque sensing motor, you do not need a gear shift sensor. The motor responds to the amount of torque applied, allowing you to ease off the pedals while shifting. If you must shift a lot during high torque events, which cause you to pedal harder, you may still want a gear shift sensor for extra support. (Source)
RIDE e MTB Tip: Are you thinking about building an eBike? It isn’t very hard – Heck I’ve got step by step instructions with videos along with all the tools. Check it out 👉 How to Build a Mid-Drive Electric Bike
Are eBike Gear Shift Sensors Expensive? Where Can I Buy One?
Most eBike gear shift sensors range in price from about $20 to $50. They are sold on multiple retail sites including Amazon, Bafang, eBay, and Walmart.
What is the Best eBike Gear Shift Sensor?
One of the best eBike gear shift sensors is the Bafang Gear Sensor, found on Amazon. Usually priced under $30 and easy to install. The gear sensor will momentarily cut motor power to mid-drive motors when shifting. It mounts inline with the shifter cable and uses the cable movement to control the motor power while shifting, reducing the wear and tear on your drivetrain.
My Recommendation is the BaFang check the current prices and reviews with this Amazon shortcut link 👉 Gear Sensor & Shift Sensor for Electric Bike Conversion Kit
So, in a nutshell, a gear shift sensor for many eBikes is a must have. This device is designed to alleviate the additional wattage applied to the drivetrain, giving the drivetrain more longevity. The additional pressure applied while shifting some eBikes can cause major issues with the drivetrain and cause it to malfunction or need to be replaced.
The gear shift sensor is made to make the drivetrain function longer by cutting power to the motor temporarily while shifting. This temporary power diversion lasts a fraction of a second and is relatively unnoticeable when applied to the gear shift cable. This will save your drivetrain in the long run.