Torque-Sensed (Intelligent) Control Systems for E-bikes—Explained

Torque-Sensed (Intelligent) Control Systems for E-bikes—Explained.

BionX does a great job offering a correctly programmed E-bike motor system.

Becoming more popular everyday and wanted by most E-bike riders, intelligent E-bike control is the best way to go.   They work at different comfort levels and in varying ways so I thought some insight to them might be of interest.   Next to power and range, and overall bike quality and dependability, the control system on your E-bike is one of the key features to your satisfaction and safety.


In the early days of E-bikes they offered a simple on/off switch or a two-leveled power switch that was not connected to any kind of controlling electronics.   These worked but allowed the bike to surge heavily when powered up and the electrical arching at the switch or relay was only going to last so long before a failure occurred.   Next up was the hand (or thumb) throttle that activates a fairly simple ECU (electronic control unit) to give proportional control of the motor’s power.   These are still in use on many E-bikes.   Many prefer this and they work quite dependably.

The eFlow E3 Nitro is another E-bike that takes full advantage of this great way to control an E-bike motor.

The term Pedelec was coined to describe E-bikes who’s motors came on automatically when you pedal.   They first came to light with a Hall Sensor mounted at the bottom bracket (pedal arms) that could sense the movement of the pedals and activate the motor.   Usually working through a analog knob or a button controlled panel, you can set the power assist level that the motor comes to when it comes on.   Although they can be a little jumpy, if the maker gets all the settings right, they can work well.


When the pedelec function is teamed with a hand throttle you get dual control.   These systems can work nicely when engineered correctly and you see this set-up on lots of E-bikes in many price ranges.   I do like to see bikes with this lay-out to have an off setting for the pedelec feature so the bike can be kept from surging with power at lower cruising speeds and when you are riding in a group.   At this point and time you will find the majority of E-bikes outfitted in this manner.   I could go on about this type of control system for hours, but today we are on a different subject.

The pinnacle of E-bike control is now torque-sensed control systems.   In a nutshell, they have a very sensitive load sensor (usually mounted at the rear dropout) than sends a signal (of how hard you are pushing on the pedals) to a micro-computer which takes that information, reprocesses it and than tells the ECU exactly how much power the motor should offer its rider.   This process happens many times a second and the exact programming of the whole system is key to the rider’s comfort, confidence and safety.

I really enjoyed my time with this Gepida Reptila 1100 that NYCeWheels sent me for testing.

Needless to say, a intelligent control system is only offered on higher-end E-bikes due to the extra equipment needed to allow it all to work correctly.   What you will also find is that when it is programmed and executed correctly, it is the very best way to control an E-bike.   The seamless feel of the power and the lack of any input from the rider other than pedaling make for the best of experiences.   This is why so many E-bike makers are moving towards torque-sensed control systems on their better bikes.

The first E-bike I rode with intelligent control was a Sanyo Eneloop.   It used a semi-complicated mechanism built into the bottom bracket to sense the load on the pedals.   Although it rode well in many respects, the computer was too sensitive and the bike would surge slightly with each pedal stroke.   Because there is a varying amount of load on the pedals during the 360 degree rotation and the computer was set to respond too quickly, this surge was noticeable, but not a safety issue.   Sanyo has quit producing the Eneloop.


The next E-bike I experienced with torque-sensed control was the Gepida Reptila 1100.   This very high-quality bike uses a set-up much like the many hitting the market right now.   It was a true pedelec with no hand throttle.   That is the European spec as they don’t allow a dual-control system as of this moment.   (You will find that most US torque-sensed E-bikes do come with a hand throttle).   This bike rode well, the control was superb, yet a few of its drawbacks are still seen in the many E-bikes fresh to the market with this control system.   More on this in a moment.

Because it works so well, the BionX is seen on many maker’s E-bikes and can also be adapted to most any bike you may already have.

On to the BionX.   They did the homework,   They spent the time on R&D.   They have mastered what makes intelligent control what it is today.   The programming of this system is the benchmark that others should copy to a T.   Unfortunately many don’t seem to be using the tools a system like this offers to make a safe and comfortable E-bike that all can enjoy.   So far in the newer to the market E-bikes I’ve ridden, the eFlow E3 Nitro is the only one that  brings it together similar to a BionX.   (I am sure there are others though).


The programming is what makes the difference in how the bike responds and rides.   There is a little more to it also, including if the throttle can be used in conjunction with the automatic assist or if by pushing buttons you have to choose one or the other.   The quality of the programming has to do with how quickly the power comes on when you start pedaling, how quickly it turns off when the pedaling stops.   How smoothly it engages and the amount of steps (power levels) it offers during your ride are important considerations too.

This mid-drive Focus Jarifa enjoys torque-sensed control. It was great fun to ride.

From a safety and efficiency stand point, I think it is important that the motor cannot come to life until the bike has attained some forward motion.   Just a simple thing like waiting at a stop resting your foot on the pedal can allow power to be wasted and the potential of the bike getting away from you.   Also if you are pushing the bike backward and the pedals jam on the kickstand, the unintended rush of motor power can be a big safety hazard.   These are points BionX and eFlow understand.   They must have some forward motion before the motor will run.

Being able to use the hand throttle at any time during your ride can be very important.   The BionX and eFlow allow this, while others require you to take your eyes off the road and your hand off the bars to toggle a button to change between the two modes.   Plus I am seeing some makers adding an unmarked ’walking’ button designed to allow you some motor power when fording a steep hill un-mounted from the bike.   This is not needed and is just another major safety issue I see.    If you need to add power when walking, using the hand throttle is the way to go.

One bright spot on the E-bikes with poorly programmed torque-sensed control systems is that they can be up-dated to better and safer operation.   Although this can only be done when the makers start to realize the need and offer those up-dates.   All the tools needed are built-in to the bikes and when the time comes I do feel like every maker will climb on-board.   This is still building technology and the future can sometimes be a rocky road.   Many of the E-bikes I ride are prototypes and the final programming hasn’t been chosen.   I do my best to give them feed-back to help guide them to what I feel is the best and safest way for these systems to operate.

The Stromer is well respected and part of that comes from the torque-sensed control system.

I could go on for a long time about this subject.   It is up to you to fully investigate all the features of any E-bike you are purchasing to make sure you are happy with all the programmed functions.   And too, you may have a different opinion on the way the programming should be than I do.  That is normal, yet I have been doing this for quite a while and have ridden many of the bikes in question.   I am a stickler for control system confidence, comfort and safety.

This also goes towards internet buying.   There is no way for you to evaluate your bike purchase on the net.   You need to climb aboard, ask questions of the salesperson and really ride the bike long enough to be satisfied it is what you like and safe to ride.   Unfortunately price shopping on E-bikes with torque-sensed control system can get you in trouble too.   I am seeing the market flooded with unsafe E-bikes that cut over a thousand or more from the price point of the better bikes.   You do get what you pay for.

I have written much on these systems and the bikes with them.   If you want more information just scan my reviews, the opinion section and the E-bike general interest section.   And don’t hesitate to ask any particular questions that you have about this subject.
Keep E-biking, Turbo Bob.

“To sweep down hills and plunge into valley hollows; to cover as on wings the far stretches of the road ahead and to find them in bloom at your approach.”—Alain Fournier, The Wanderer.


About Turbo Bob's Bicycle Blog

E-bike Enthusiast Vintage Bike Enthusiast
This entry was posted in E-bike general interest, Opinion. Bookmark the permalink.

4 Responses to Torque-Sensed (Intelligent) Control Systems for E-bikes—Explained

  1. rbs says:

    I think progress is being made in this area. However, what we need is OPEN STANDARDS not more proprietary solutions that keep the costs artificially high. I personally use the Cycle Analyst on my bike and really wouldn’t know how to ride properly without this information. I have so much more fun on my bikes now that they are electric, and the cycle analyst helps me avoid riding mistakes and creating too much stress on components.

    I still see the market needing to address ergonomics more. And I’d really like to see an Ebike Specific Quick Release System developed that is safe and easy. And that system would include integrated plug and play harnesses that made it easy to remove and replace punctured tubes and worn tires. I’d like to see better weight distribution (As so many of the components make the backend heavy or the entire bike so heavy that it’s a chore to ride with the power off).

    I find myself using the cruise control feature integrated with my controller quite often now. Without it the bike will sometimes “pulse” if I’m not real steady with the throttle.

    Personally I think a better implementation of the forward pedaling/thrust before the motor can “come to life” as you say would be a computerized controller that ramped power smoothly. Perhaps an option to select how much “ramp up” you want. I want to be able to ride in an emergency (Broken chain, broken derailleur, etc.) without the need to pedal. I know that happens almost never, but I’ve experienced it.

    I have a 3 speed switch on my bikes and it helps some, but I still sometimes forget how powerful the rear wheel is and “wheelie” start from time to time.

    Once again well written and you are addressing real world issues that will just make things better. Lets hope the manufacturers listen to your suggestions. I look forward to your posts.

    • Thanks for the response RBS. Standards have been implemented in some forms of transportation (for example—aircraft instrumentation), yet I would be surprised to see it on E-bikes. We can hope though.
      My concerns for safety on all E-bikes is very high. Plus rider peace of mind and a lack of uncomfortable and disconcerting unexpected motor activation rank high in my thoughts.
      Even a non-moving bathtub can cause injuries, so riding a bike has its injury possibilities. I just don’t like the see the addition on a electric-assist system adding to the equation.
      Please continue to add your words to any post you see fit.
      Biking rules, Turbo Bob.

  2. Ashly Young says:

    My 48v 500w ebike has a back hub motor and Everytime I put the throttle on it makes a loud studdering noise and most times I have to spin the wheel just to get it going at first…while having throttle on

  3. I would suspect the controller or the sensors in the motor.

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