What It Takes to Design an E-bike Handlebar Controller?

Nov 11, 2019 at 3:58
by Revonte  
The handlebar controller is essential, but still oftentimes an overlooked part of the e-bike drive system. The whole ride experience is largely depended on the controller since it forms much of the human-machine-interface.


The Controller Design
Revonte ONE Drive System
A rendered version of the ONE Controller.

In some instances, it almost feels that the handlebar controller is just a necessary evil that has been slapped on top of the motor since it is part of the package. Here at Revonte, we decided to take a different route and make things right from the start by designing our own controller from the ground up.

Part of the Package
Revonte is a new manufacturer in the field of e-bikes. The Revonte ONE Drive System is the first stepless and automatic drivetrain which eliminates the need of the cassette and rear derailleur. Since most of the readers are more or less technically savvy, some of the numbers "under the hood" are listed below.

We are not only about the raw numbers though. Power means very little without control. The Revonte ONE Drive Unit has its foundation on solid mechanical engineering and is further enhanced with sophisticated software. This combination gives our solution to a high level of configurability. Since the very successful launch of the Revonte ONE System in Eurobike this year, we have been busy with testing and getting the product finalized for production.
Technical specifications
• Power: 1.5kW peak, 250W nominal
• Gear range: 416% at 60rpm
• Q-factor: 180mm
• Chainline: 57.8mm
• Weight: 4.7kg (drive unit)
• Battery: 36V, 635Wh, 3.98kg
• For more info, see our previous press release.

bigquotesThis is a step into the right direction, big time! You can either have this in automatic mode or have it customized to whatever you need. What I'm talking about is a combined motor and a drive unit at the same time. So drive unit as in the gears on a bike. I mean this has got to be the future of e-mountain biking!Steve Jones, EMBN.com

On top of the considerable amount of engineering that has gone on the mechanical and software side of our system, we have taken great care with the design process of our controller - as you can see below.

Core Values
The term core value is usually mentioned with company policy or business strategy. We've employed the same tool and line of thinking on the level of individual components. This was the case with controller controllers since it is such an important part of the system and user experience. After careful consideration, idea gathering sessions and feedback from the every-day user all the way up to the professional level, the core values were condensed in the five following points:

• Intuitive. If the rider needs to think about how to use the controller or the learning process takes a considerable amount of time, the design hasn't met this goal. In other words, controlling the behavior of the bike must become effortless according to the “No look” principle.

• Screenless. An overflow of information will distract the user while riding - keep it simple! We believe that all the needed information can be conveyed through a led indicator. Our drive system does not require a screen and if the user wishes to use one, mobile phone or a dedicated ride computer will provide a platform for all the information imaginable and most importantly, with a customizable view. More on this later.

• Right-hand side. Since the traditional shifter is gone and there is space to occupy, the right-hand placement is an obvious one - especially for mountain biking - and supports what the rider is used to at this location. A placement like this declutters the cockpit setup and creates a more streamlined and elegant look.

• Integrated. The goal was to integrate the controller into the cockpit rather than occupying any new space.

• "The rule of thumb". By this, we mean that the controller can be operated using the thumb only so that the index finger remains free for braking purposes, therefore adding safety and confidence. This is an obvious design feature for general trail riding and other rowdiness done outside the paved roads.

Design Drivers
From core values, we moved on to a more practical level. Design drivers are properties or features that we want you – the rider – to notice when using a bike equipped with the Revonte ONE Drive System. In this case, there were some similarities between them and core values, but the list got diversified and most importantly, more exact. All of the points were considered carefully and verified with the feedback from professional mountain bike riders as well as every-day users.

Revonte ONE controller
A bit more than a napkin sketch.

• Simple & intuitive design. All of the relevant functions to riding can be controlled underneath the handlebar by using the thumb only.

• Versatile. Works on multiple platforms. No matter the handlebar setup, bike or ride computer you are using, our controller will be compatible.

• Simple & compact. The form and use should be broken down to a minimum without sacrificing features and functionality. No one will benefit from a huge clunky controller with too many buttons.

• Stealth & integrated design. No matter how good the function is, if the end product is an eyesore, it has not met all the goals – or not at least in our books. Smooth surfaces, shapes, tactile features, alloy construction on levers and a nice color scheme are a must-have. Our controller integrates itself seamlessly to the cockpit.

• Great ergonomics. Although this is an obvious criterion, not all designs meet it. The controller should be comfortable to use, it should not require loosening the grip and reaching when used, etc. These are basic things and therefore something that we want to make especially well.

• Future-proof. We included a modular element into our design to make it as future-proof as possible. This gives us the option to modify user-interface, including the paddle structures. More about this later on a whole separate article!

The list does not end here, though. Besides, the design drivers listed above, there is a hefty list of requirements for the design. Since we are dealing with electronics, the structure has to be waterproof to keep the system functional. Our controller design fulfills the conditions for the IPX7 & IPX6 standards which means that it can be washed with a water hose. You can keep your bike nice and clean, even though it is note solely powered by muscular force. On top of that, the design has to meet the recently renewed EN15194 e-bike safety standard and Machinery Directive 2006/42/EC.

Where's the Display?
Continuing on the previous point about the screen. Although the decision to leave the screen out might seem somewhat counter-intuitive, we made it early in the design process. The reasoning behind it is quite simple.

First of all, there is a limited amount of information that is useful when riding. Even if you ride in a straight line without any features or obstacles, eye-contact should be kept forward. If eye-contact wanders off from the optimal line choice, usually trouble ensues. Given these points and the fact that not too many metrics are useful to observe while riding, a need for a screen does not really present itself. When it comes to post-ride analytics, the situation changes of course. Ride data can be viewed and analyzed from a mobile phone or from a laptop interface.

A second reason for leaving the screen out is that we want to give the control and customizability back to the user. If he or she wishes to use her own device, the option exists and is even the preferred one. The companies who manufacture ride computers know their job and we trust them.

Closing Thoughts
There you have it. Those were the basic factors that guided our design process which resulted in innovations all the way to the level of filed patents. A component like a controller seems simple on the surface but the number and depth of decisions are quite surprising when the design challenge is truly tackled. The final product ended up being quite a lot like our motor: functional, robust and almost elegant in all of its simplicity.

The Revonte ONE Remote
Fucntional prototype; very close to the final production version!

No corners were cut in the process. We are happy with the end result and confident that you will like it as well. Stay tuned for more information and news about the Revonte ONE Drive System on a later date! While doing so, please do sign up for our newsletter at Revonte.com.


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