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