Electric bikes are equipped with special sensors that continuously read data from the pedals and allow the controller to apply motor power in a precisely measured way - according to the current need.
There are two types of sensors - cadence and torque. They calculate the "current need" using two very different principles, which you need to know before you make a model choice.
CADENCE SENSOR measures how fast you're pedaling. The higher the cadence, the easier it is for you, so the system provides less electric assistance.
TORQUE SENSOR measures how much force you're applying to the pedals. The more pressure you apply, the harder it is for you, so the system provides more electric assistance.
They operate so differently that the riding experience feels completely different.
PAS
Any e-bike, regardless of sensor type, lets you adjust the PAS (Pedal Assist System) level with "+" and "-" buttons when you are riding to dose the delivered motor power depending on changing conditions. Each PAS level is mapped to a pre-set percentage of the motor's maximum power, adjustable in settings. For example, PAS1 may deliver 20%, PAS2 28%, PAS3 36%, etc.
However, the meaning of PAS levels differs significantly between the two types of sensors, as will be explained further.
*** CADENCE SENSOR ***
PAS LEVELS BEHAVIOR
Each PAS level is mapped to a certain speed when you are riding on a completely horizontal road. For example, PAS1 might take you to 13 km/h, PAS2 – to 17 km/h, PAS3 – to 21 km/h, etc. - but never exceeding the bike's maximum speed, at which point the motor always shuts off automatically. I don't think this mapping is done in the software - probably, the given power is simply enough to reach the corresponding speed, since the speed drops on uphills.
The strong link between power percentage and minimum speed can be frustrating - you can only change them together, not separately. Most of the time that's fine, but not always.
As soon as you start pedaling, the motor engages and quickly accelerates the bike to the speed mapped to the current PAS level. Once that speed is reached, the motor maintains it on flat terrain. You can keep accelerating beyond that by pedaling actively and reach any speed you want or can - while the motor continues to assist you.
That minimum speed is maintained even if you're pedaling very slowly, with zero effort. This is known as "ghost pedaling". It doesn't move the bike mechanically but only signals to the sensor that you want to keep going. If you completely stop pedaling, the motor immediately stops.
An important point: the Cadence sensor ignores how hard you press the pedals. If you intuitively push harder in hope to go faster or climbing an uphill, the motor won't help you. Even worse - you can get the opposite effect: if your hard pedaling increases cadence, you decrease the motor assistance. So, you have no choice but press "+" in such a situation.
A small remark. I've repeatedly seen comments on Facebook claiming that a Cadence sensor is not actually a Cadence sensor, but rather an on/off switch, meaning it would be more accurately called a movement sensor. On my bicycle with a Cadence sensor, I had the ability to view the battery consumption in real time, and I can confirm that it is indeed a genuine Cadence sensor - the amount of delivered electrical charge clearly decreases when pedaling faster. During ghost pedaling it might register a few Ah (depending on the PAS level), up to the max Ah of the battery (20 Ah on my model), but with high cadence it would decrease to 0.6 - 0.3 Ah, occasionally even reaching zero.
HOW "+" AND "-" BUTTONS WORK
With a Cadence sensor, you're constantly pressing the "+" and "–" buttons to regulate speed. This very closely mimics a car's cruise control, just with a larger "step". You become a slave to the right PAS level - otherwise, you end up going too fast or too slow. This constant juggling of PAS settings takes a certain level of multitasking, especially when combined with the need to shift gears. And all of that - on top of watching the road and staying alert for safety, not to mention admiring the scenery, haha!
SETTING UP PAS LEVELS
For more precise speed control, change the default 5 PAS levels to 7 or even 9.
Setting the first (lowest) PAS level:
Sometimes, the factory setting for the lowest PAS level is too high. On my first e-bike, it was 50%. That's crazy! You can either ride by pedaling only (PAS0) or ride with a pretty high speed (PAS1) with no options in between - but the missing options are the most necessary ones for casual riding. My advice is to set the first level to the percent that will carry you on flat terrain while ghost-pedaling at a speed of 11 km/h (7 mph). You will use this speed for accurate, precise control while slowly passing sharp turns. Of course, if a turn is very sharp and the road is narrow, it's better to switch to PAS0 and rely solely on pedaling, but, still, PAS1 will be useful in many situations. On my bike, I've found experimentally that it's 25%.
Setting the last (highest) PAS level:
Set it to 96% to help protect the motor from overheating on sharp, long uphills.
If the riding conditions allow and your bike has a throttle, you can make the last level 70-80%, and if necessary use the throttle - this will reduce the step size between levels (this idea is especially good if your model has only 5 levels).Setting the in-between PAS levels:
The rest of the numbers should be distributed almost evenly between the lowest and the penult PAS levels. I wrote "almost" since steps in the higher area of the range can be bigger. You will use last levels pretty rarely, only on steep uphills, where you want a big increase immediately (a small increase will hardly be felt). For example:
5 levels: 25%, 35%, 45%, 57%, 70%
7 levels: 25%, 35%, 45%, 55%, 65%, 80%, 96%
Some models have 9 levels - including the one I rode. But I found that too many - very fine tuning of speed is not needed, and having to press "+" and "-" too often is annoying.
And the last thing I want to write in this regard. I discovered an interesting thing on the model I rode: setting PAS1 to 10% results in the motor never being engaged (the display always shows 0.0 Ah) - just like with PAS0. But, in contrast to PAS0, the throttle is available! This is a very good feature rarely found in e-bikes - you can ride without electrical assistance at all (for exercising), but the throttle is at your service to reach the desired speed and then pedal, to overcome a short hill or in an emergency situation. I changed the mode from 0-7 to 1-7 to make the throttle available always - even immediately after turning on the display - and selected the following values:
10%, 25%, 35%, 45%, 55%, 70%, 85%
RIDING SENSATIONS
The Cadence sensor feels very unintuitive. As soon as you start pedaling when the PAS level is not minimal, the bike sharply surges forward like a wild horse. Then, unlike riding a regular bike, slowing down your pedaling doesn't result in a decrease in speed as you might expect. The motor can't tell that you're putting in little effort - the low cadence makes it think you're struggling to climb an incline, so the motor delivers maximum power for the current PAS level. And when you try to increase the PAS level to make pedaling easier, the bike suddenly surges forward again, even if you just wanted to maintain the same speed with less effort. You end up feeling disconnected from the bike - it sometimes seems to do its own thing, and your control over it feels limited.
MANEUVERING AT LOW SPEED
When approaching a sharp, narrow turn - like a T-intersection in a park trail - you must switch to PAS1 or even PAS0. If you forget to do that because you're lost in deep thought, the bike will continue to run with a high speed, leaving you no time or control to make the turn safely. This is extremely dangerous and could result in you being thrown off the path, potentially injuring yourself or others.
If you sense things getting out of control, immediately press either the left or right brake lever. Pressing it just slightly won't engage the brake yet, but it will instantly cut off the motor because the electrical circuit is interrupted mechanically. It's a critical safety feature but be aware that some cheap models might not have it, which is another reason to avoid them.
While stopping pedaling will also turn off the motor, there's a slight delay since the cutoff happens electronically. In emergencies, always rely on the brake levers. Also, in tight turns, you'll likely want to keep pedaling to maintain balance, so stopping to pedal isn't always an option.
*** TORQUE SENSOR ***
PAS LEVELS BEHAVIOR
With a Torque sensor, the meaning of the PAS level is very different from that with a Cadence sensor.
When you start riding without throttle, you exert a lot of effort. The sensor feels this and compensates for your effort with the motor so that it's not difficult for you. As you accelerate, the pressure on the pedals decreases, so the electric assistance is dropping.
The fact that electric assistance decreases as you accelerate is also a description of a Cadence sensor. But the colossal difference is that with a Cadence sensor, the pre-set percentage of power is delivered immediately, whereas with a Torque sensor, the initial percentage depends on the pressure on the pedals. Just because you can reach the pre-set % doesn't mean you will. You could immediately get the maximum power out of the motor by pressing the pedals as hard as you can and get the Cadence sensor behavior. But you certainly won't do that - for smoothness and comfort, and for precise adjustment of the desired speed. To accelerate as fast as possible, just use the throttle.
Also, each PAS level defines how much power is delivered during casual riding - when the pedal force is low to moderate. In simple terms, it defines how easy pedaling feels at the same speed, and how easy the acceleration is. The higher the percentage, the faster the acceleration with the same foot pressure, meaning it's easier to pedal during normal conditions.
The best thing about a Torque sensor is that there's no such thing as a minimum speed for a PAS level. No matter what percentage you set - even 100% - you can still ride very slowly. If the pressure on the pedals drops low enough, the motor will reduce power to a minimum or even shut off completely. At 100% PAS, pedaling doesn't just make the bike move - it acts more like a command to the controller. The pedals essentially shift from being mechanical power transmitters to becoming a data input device that tells the system how much help to give, especially at low speeds.
In contrast, if you set a 100% PAS on a Cadence sensor bike and start pedaling, all available power is delivered immediately. The bike will jerk forward sharply and, as long as the pedals keep spinning - regardless of how much effort you're putting in - it will keep accelerating until it hits the bike's speed limit.
The behavior of a Torque sensor e-bike on the max PAS is shown in this video fragment:
HOW "+" AND "-" BUTTONS WORK
The buttons aren't used to control speed - that's done with the pedals. So, you're not a slave to constantly switching between numbers in order to be on the desired speed - you gain an unprecedented level of freedom. Personally, I find that I almost always use the buttons just to toggle between PAS 1 and 0.
That also eliminates multitasking when you have to manage gear shifting at the same time.
SETTING UP PAS LEVELS
There's no need to fine-tune PAS levels to get those "in-between" speeds. Instead of dealing with a few big, fixed steps, you get stepless fine control - with an infinite number of "PAS levels" - just by adjusting how hard you pedal.
After switching to a torque-sensor e-bike, I've gone from using 7 PAS levels to just 3 (plus zero):
- 20% (the minimum on my model): It simply compensates for the bike's heavy weight, essentially turning a 50kg, $2K e-bike into a 7kg, $15K non-electric bike. I use this level almost always when I need the help of an electric motor.
- 50%: For moderate climbs. On flat terrain I feel like an Olympic champion.
- 100%: For steep climbs. On flat terrain I feel like a superman.
Since I bought the bike for exercise, I try to stay on the lowest PAS level possible. But if your goal is effortless transportation - like commuting to work without arriving sweaty or doing food delivery - just set PAS to 100% and forget about the "+" and "–" buttons entirely. The only real purpose of lower percentages is to help improve your health and fitness, and, possibly, to increase the electrical range if necessary.
RIDING SENSATIONS
The immediate, on-demand response proportionally to your pedaling effort creates a smooth, natural and intuitive riding experience. It feels like you're riding a regular bike - the motor simply amplifies your pedaling. You feel very connected - the bike is doing what you want, not what it wants.
MANEUVERING AT LOW SPEED
Sharp, narrow turns are obviously much safer and easier with a Torque sensor. There's no need to lower the PAS level beforehand even if you're at the 100% PAS - you intuitively slow down by easing off the pedaling, just like on a regular bicycle. I've often noticed that when maneuvering at very low speeds, I'm using pedal pressure solely to control the motor's output. The force is so minimal that it's almost like ghost pedaling - just sending a signal to the controller about the speed I want.
Once the turn is completed, just start pedaling harder to return to your normal speed - again, without pressing any buttons.
RIDING ON FULL AUTOMATIC!
Note that if your e-bike has a hub motor, then you can enjoy a "fake" automatic transmission.
The hub motor enables the "single-gear bike mode" - you set the gear on which you ride most often, and don't change it since you don't have to downshift before stops - you can stop at any gear, even the last one. Then, you start moving with the throttle, and switch from the throttle to pedaling after gaining some speed.
The combination of the "single-gear bike mode" (no need to switch gears) and the Torque sensor (no need to change PAS levels except of steep uphills) brings the experience of an automatic transmission. At low speeds, when the cadence is minimal, pedaling doesn't move the bike physically (as I wrote earlier, "The pedals essentially shift from being mechanical power transmitters to becoming a data input device that tells the system how much help to give"). That means low cadence will not kill the drive train as it would in mid motors where low cadence is synonymous with enormous stress on the chain and sprockets - so you can ride with low cadence without any worries.
The only situation where you'd want to shift to a higher gear is during a fast descent. For example, you might constantly ride in 4th gear, but on a long downhill, you'd shift to a higher gear to avoid too fast or even ghost pedaling - if you're using the bicycle for physical activity.
IS THE CADENCE SENSOR PURE EVIL?
Upon reading this page, you might have gotten the impression that I lead a Sect of Cadence Sensor Haters. This is not at all the case. I began writing this article shortly after switching to a bicycle with a Torque sensor, and my enthusiastic impressions likely influenced my writing style (I guess I'm overly emotional). But in reality, everything in this world has its own advantages and disadvantages. So, now I will list the pros of the Cadence sensor.
1. Physical ease of riding.
With a Torque sensor, if you want more power from the motor, you have to pedal harder. We're not talking about the throttle here - it's useful for short bursts, like quick acceleration or steep climbs, but not ideal for casual riding (you don't want to immediately pick up the maximum speed after each stop or slowing down). Also, some e-bike models don’t have a throttle at all.
Although the Torque sensor responds to how hard you push the pedals, the pressure still needs to be reasonable. If you pedal lightly, the bike will move slowly. If you ghost pedal, the bike will eventually stop - even at 100% PAS.
Riding my 1000W Himiway D7 on flat terrain at 100% PAS feels very easy - it's not far from ghost pedaling. But I've heard some people on YouTube complain that, on less powerful torque-sensor models, pedaling isn't that effortless even at full PAS. And when going uphill, I also need to apply significantly more pressure - especially if the slope isn't steep enough to justify using the throttle.
The need to apply pressure is a huge advantage for my training goals. However, this can be a downside if you want an e-bike to get from A to B with minimal effort - more like a moped. In that case, especially in hot weather or in a hilly city, a Cadence sensor might actually be the better choice.
2. Precise dosage of training load.
On a bicycle with a Cadence sensor, it's easier to precisely regulate effort when you are in a low gear. To train more intensively, I can deliberately decrease the PAS level in order to force myself to push the pedals harder to maintain the same speed. On a bicycle with a Torque sensor, pressing hard on the pedals leads to a significant increase in speed even at the minimum PAS level, while the leg effort is less than desired. Perhaps this is happening on my model because it's powerful, and even the minimum 20% (PAS1) is too much. This becomes a problem when the road goes slightly uphill, and pedaling without the motor is too difficult (while with the motor, it turns out to be too easy - I need something in the middle!). For a quality workout, I need to ride at higher speeds and gears, which isn't always possible. For example, when the path in the park turns or winds significantly, I have to greatly reduce pressure on the pedals to decrease speed. Actually, I ride for athletic purposes, so such slow riding is a waste of time.
With a Cadence sensor, you enjoy a broad range of effort levels - from ghost pedaling (zero effort) to intense pedaling - with precise adjustment available through the PAS buttons. With a Torque sensor, you've exchanged these capabilities for the convenience casual riding.
3. Long riding with the throttle.
There's a neat trick that definitely works with a Cadence sensor (not sure about Torque sensors - I haven't tested it): you can ride for a long time using only the throttle, without pedaling at all, while still being able to control your speed - basically like riding a real moped.
To do this, you need to adjust the settings so the throttle doesn't accelerate you to the bike's full maximum speed (which is the default behavior in most e-bikes), but only to the speed associated with the current PAS level. That way, pressing the throttle will work exactly the same as ghost pedaling. With this setup, you press the throttle and ride, adjusting your speed using the "+" and "–" buttons only.
Since the speed scale becomes completely stepped (you can't fine-tune it with pedaling anymore), it's best to set PAS to 9 levels, so each step is smaller and gives you more precise speed control.
If you're serious about using this method, install a twist throttle - holding down a thumb throttle for long periods can get tiring. The twist throttle works like this: first, twist your palm away from you, then grab the throttle ring and return your palm to the normal riding position. Then, use your body weight to hold the ring in place and prevent it from snapping back - instead of squeezing it with your fingers.
4. Lower price.
The Cadence sensor will save you money. Almost all lower-cost e-bike models come with a Cadence sensor. In fact, Torque sensors are relatively rare - they're typically found in mid-drive motor bikes, which are more expensive by nature, and only in a few rear hub motor models. The Cadence sensor remains popular mainly because it's affordable - and because most potential buyers haven't come across an article like the one you've just read.