Electric bikes work by augmenting your pedal power through the use of a motor, but these bikes need to know when you’re pedaling in order to assist.
E-bikes do this through the use of either a cadence sensor or a torque sensor.
Both sensors function to tell the motor when to start/stop (during pedal assist), but they go about it in different ways and they each have their own advantages and disadvantages.
Long-story-short: torque sensors offer a smoother, more efficient ride, but usually cost more; cadence sensors are quite a bit cheaper, but don’t offer the same fluidity.
If you’re interested in the longer story, keep reading.
In this guide, I’ll go over all the main points you should know about these integral e-bike components before making a purchase.
After reading, you’ll know which sensor makes more sense for your next e-bike.
Well, let’s get to it already.
If you’re new to electric bikes, you may be a little fuzzy on how these things work in the first place.
Well, it’s all about pedal assist (PAS).
Technically, I guess it isn’t all about pedal assist because a lot of e-bikes have throttles too, but all e-bikes will most certainly offer pedal assist to some degree.
This is kinda the point of an electric bike.
PAS refers to the process of the motor kicking in to help you pedal and most e-bikes let you select your PAS level to determine how much assistance the motor provides.
This is different from the throttle, which allows you to push a button or twist a grip to get motor power without pedaling.
Being able to select your PAS is great because sometimes you may want less motor so you can still get a workout in, while other times you may want the motor to do all the work.
Cranking up the PAS level can come in real handy when having to climb steep hills.
The presence of pedals and the ability to still manually pedal your e-bike is what sets ’em apart from an electric moped or even an electric motorcycle.
But as mentioned in the intro, your e-bike’s motor needs to know when you’re pedaling in order for it to know when to turn on and off.
Enter cadence and torque sensors.
Cadence sensors are the most common e-bike sensors because they’re more affordable – you’ll see these sensors on pretty much any e-bike under $2k (although there are a few exceptions out there).
These sensors simply detect when you start pedaling and turn the motor on; when you stop pedaling, they turn the motor off.
Cadence sensors work through the use of a magnet on the crank arm and a sensor that detects when it starts moving.
This sends a signal to the motor to cut on and vice versa when the detector sees that you’re no longer pedaling.
The amount of motor output you get will depend on which PAS level you’re on (higher level = more assistance), but otherwise you’ll get all the assistance for that level regardless of how fast or hard you’re pedaling.
Juiced Bikes likens this to turning on a traditional light switch – you flip the switch and the light is all on or all off.
The biggest advantage to a cadence sensor, other than being more affordable, is that you don’t have to work hard to get the full benefit of the motor.
You can pedal lightly and still get full motor assistance, which can be fun (aka ghost pedaling).
But if you’re looking for a more natural feel, going with an e-bike that uses a torque sensor could be worth it.
- More affordable
- Constant power
- Don’t have to pedal hard to get full power
- Not as efficient
- Pedal feel not as natural
- Not as good for people looking for active ride
Torque sensors use precision strain gauges that can tell how hard you’re pedaling and they tell the motor to help more or less, depending on how hard you pedal.
If you pedal harder, the motor will give more assistance to match your effort; pedal lighter and the motor will help less.
This is a more sophisticated technology and this is why e-bikes with torque sensors usually cost more (most start around $3k, but we’re seeing torque sensors on more affordable bikes now too).
The biggest benefit a torque sensor offers is a more natural pedaling experience.
In these e-bikes, the motor isn’t taking over, it’s just making your job pedaling easier. It’s kinda how it would feel if you had robot legs they were a lot stronger.
You can still have PAS levels with a torque sensor, but the amount of motor assistance will still vary for each PAS level depending on how hard you pedal.
And since the torque sensor alters how hard the motor is working, they tend to extend the bike’s range between charges too.
Torque sensors are great for people who want a more active experience on their e-bike or for folks looking for optimal performance, but they might not be optimal for people looking for a less active ride.
If you like the idea of barely pedaling (ghost pedaling) and still getting full horsepower, you might actually prefer the feel of a cadence sensor.
Hey, there’s nothing wrong with riding your e-bike for pure enjoyment, I get it.
If a cadence sensor is like a traditional light switch, then a torque sensor would be more like a damper that lets you select how much light you’re getting.
- More natural pedaling feel
- More efficient for battery
- Great for riders looking to stay active throughout ride/improve performance
- More expensive
- Have to pedal harder to get full power
- Not great for folks looking to ghost pedal
When comparing electric bikes, there are a lot of specs and features to consider – motors, batteries, ranges, sizes, etc.
But if you dive a little deeper, it’s worth considering what kind of sensor any prospective e-bikes use.
Budget alone might decide for ya, in the case of cadence sensors, but if you’re working with a larger budget, you’ll have a decision to make.
If you want a smoother pedaling motion and are looking for a more active riding experience, going with a torque sensor could make a lot of sense.
If you’re just looking for a fun bike to cruise around on and aren’t looking to work too hard, going with a cadence sensor could make more sense.
Even though cadence sensors are considered to be the more basic technology, they still work great.
It all really depends on your budget and what you’re looking for out of your e-bike.