Revonte Drive System Offers the Highest Level of Configuration

The Revonte Drive System development has had two distinct phases: hardware and software. Most importantly, they form a unit that works harmoniously together in a way which is unprecedented in the e-bike market. First of all, the mechanical structure of our motor is simple and ingenious in its own right and when the broad scale of software-driven features are added into the mix, we can reach a new level of performance and customization. Today we are going to concentrate on the latter one. 

To Customize What?

Current e-bike drive units offer very little room for customization. Sure, there are different levels of assistance which might have some room for tuning but that is about it. A high degree of customization benefits all parties: the bike manufacturer and the end-user – meaning the rider. Let us explain how.

Let’s start with the bike manufacturers point of view. With Revonte Drive System the manufacturer can configure the motor properties however they want. Even though two bikes have the same motor and software, the ride characteristics and even the digital user interface might be completely different. The motor performance can be tuned to fit the needs of any type of use: commuting, road riding or mountain biking. For example, a cargo bike can have significantly higher torque values when accelerating than a regular city bike. This is just one simple example of the degree of tuning and customization that can be done by the bike manufacturer. 

From a rider’s point of view, the assistance modes can be configured – on top of choosing the assistance mode itself. If an avid mountain biker wants more “kick” during acceleration, it can be done through our app. Besides basic functions like these, the bike can learn commonly used routes and optimize functions towards them. The goals of route optimization might be anywhere from the fastest time possible to an option that has the best combination of travel time and battery life.

Customization Is an Asset

One thing that no manufacturer wants – be it inside or outside of the bike industry – is bigger and more complex inventory. With the Revonte Drive System, both are minimized since our motor can be fitted to any type of bike. “One motor to rule them all”, is a catchy slogan but well justified one in many respects. Single motor model and software means simplified and most likely smaller inventory, which makes the bike manufacturers business easier and their product manager happier. On top of this, even the smallest manufacturers can have the customization capabilities that were previously available only to the biggest players in the market. Varied customization options give more possibilities to differentiation and creates a more varied and competitive market environment which will eventually lead to more refined products. That is a win-win situation in every way.

From an end user’s perspective, customization is the ticket for the most enjoyable riding experience – whatever it means to the individual in question. A true tinkerer might find it interesting to search and try every cranny and nook that the motor and software offers. On the other hand, setup and forget style of approach is just as justified and would most likely meet the demands of an individual who uses an ebike just for an occasional or perhaps a daily commute. This, of course, topped with the basic choice of running our exclusive automatic transmission mode or a more traditional indexed type of shifting.

The App

Our system does not include a screen beside the LEDs that are embedded in the remote controller that sits next to the right side handlebar grip. This is one more feature where we give the freedom to the end-user to customize the cockpit area. The default mode is an ergonomic and “stealth looking” cockpit, but a big screen can also be used via our mobile app. If you want to have all the relevant ride metrics visible, it can be done through the app or by a 3rd party ride computer (e,g. Garmin, Sigma etc.) Our app gives the most thorough metrics since it acts as a user interface and dashboard for the bike’s ride characteristics. Besides that, our app has continuity built into it; the more ridden kilometres add up, the more refined adjustments and preference settings can be done based on the private user data. In short, one can go minimalist with a screenless setup or have all the bells and whistles imaginable by using our app. 

To Sum It Up

In our eyes, strong and robust design with broad customization possibilities was missing from the market. We wanted to make things differently from the ground up and ended up with technology and design that has not been used in e-bikes previously. We see the wide-ranging customization options as a strong asset that benefits everybody involved in the bike industry – bike manufacturers and the riders, you included.

All of these configuration possibilities (and much more!) are achieved solely by software, without the added complexity of levers, switches or other mechanical structures that were considered cutting-edge technology in the 20th century. Using a single hardware solution, or at least one with very limited configuration options is the route that the electric car industry has already paved. Why wait any longer in taking the steps in the same direction?

Automatic Transmission is the Future of E-bike Drivetrains

If you are visiting our site for the very first time, our drive system and the principles behind it aren’t most likely familiar to you. The Revonte Drive system is based on integrated automatic transmission – a technology which has been used in a wide range of industrial applications. In the car manufacturing world heavy hitters like Subaru, Nissan, Toyota, Honda, Mitsubishi, Volkswagen, Audi and Mercedes have made their own application of it. It’s about time to apply the time tested technology to two wheeled and (mostly) human powered vehicles! As you will learn later, our drive system does offer significant and even unheard benefits and ride qualities when it comes to e-bikes in particular.

What it is?

We at Revonte have created a new type of e-bike motor and drivetrain construction which is based on principles and technical design of an Automatic Transmission. The technology principle itself can be considered quite old. In this case that comes with a considerable advantage. If a technology has stood the test of time it means that it is highly functional and in this case robust. The principle behind our drive system could be described even as stylish in all of its simplicity. Besides the ingenious principle behind the automatic transmission technology we’ve made a considerable effort to make it light and compact by means of mathematical modelling and simulation. After all the hard work, we can say that the result is very pleasing.

The “hardware side” is only half of the equation, although an important one. Besides that the technology is more robust than any other existing one in the e-bike market, our motor ride qualities are highly adaptable via software. This means two quite profound things:

  1. More adjustability and choices for the rider – more on this later.
  2. One motor can be used in all bikes, no matter the intended use and application.
Integrated automatic transmission frees the bike from the derailleur and cassette.

The benefits – what it does?

The term “automatic” gives a strong clue what’s to come. To quote Wikipedia page:

“Shiftless transmission, single-speed transmission, stepless transmission, pulley transmission, or, in case of motorcycles, a ‘twist-and-go’, is an automatic transmission that can change seamlessly through a continuous range of effective gear ratios.”

Not only is our motor automatic which enables the rider to pedal on self-selected cadence, but it’s also stepless! No matter if you’re riding uphill, downhill, headwind, on gravel or the smoothest tarmac there’s no need to make gear changes, the motor and software does the work for you in that department – continuously. Later we will cover what this means specifically in different types of riding applications, like MTB, road riding, touring etc. But let’s not get ahead of ourselves in that direction. Stay tuned.

Would you prefer the traditional indexed shifting? No problem. Our software can also be adapted to that. What about the number of gears, would you like to run 5, 10, 12 or even 20-speed? Once again, no problem. This can also be achieved just by the software settings alone.

Last but not least is that our drivetrain employs a single-speed setup – at least to the uneducated eye. All the gear ratios, automatic transmission or indexed gears are achieved by use of a single chain (or belt, if you like). This brings the drivetrain complexity down by several magnitudes meaning fewer braking parts, maintenance and therefore unwanted headache.

It goes almost without saying but it’s still worth mentioning that our motor is located around the bottom bracket. This keeps the center of gravity (COG in short) at the center of the bike and as low as possible, which produces superior handling characteristics. There aren’t any other options for motor placement when it comes to riding characteristics and simplicity of construction. In short, locating motor around the bottom bracket is the superior choice in every aspect.

What’s next?

Sounds promising, we’d assume? What will happen next? Stay tuned for more regularly appearing articles and blog texts on this site where we’ll be describing the motor and its characteristics with growing amount of details.

The bicycle drivetrain has followed the path of incremental improvements for nearly a century. It is quite clear that the current technologies have been “maxed out” in every aspect. Our goal is not a small improvement on top of existing technology, rather a revolution.

Viva la Revonte!

Optimizing the motor and the CVT

Hi there – nice to have you reading this! My name is Dr. Antti Lehikoinen (just Antti will do), and I’m working as a special advisor for Revonte.

This post will take you through what our team has spent the last few weeks on – optimizing the Revonte drivetrain. It’ll cover the benefits and workings of the CVT drivetrain, some challenges we’ve faced, and finally the basics of modern optimization. I’ve tried to keep the amount of raw tech to a minimum, to make the text readable to anybody who understands bicycles.

Please let me know in the comments if I made it or not 😊

Why CVT?

As you might know, the Revonte drivetrain utilizes a continuously variable transmission, otherwise known as a CVT. As its name suggests, a CVT does not have a discrete set of fixed gears. Instead, any transmission ratio (within a certain range) can be reached.

But why use a CVT, you might be wondering. Why not simply have a traditional bicycle gearbox or wheel stack?

Well, there are several reasons for that.

First, a standard fixed-gear transmission has, well, fixed gear ratios. Anybody who’s ever ridden a plain 3-speed bicycle has certainly been climbing a moderate uphill where gear 1 was far too slow, while number 2 was already a tad too heavy. Of course, you could avoid that situation by riding a fancier 21-speed mountain bike, but then you’d be spending far more time going through gears once that uphill suddenly turns into even ground.

Which brings us to the next item: a 21-speed gearset obviously has lots of parts. It’s heavy, there are more parts to service and maintain, and a higher chance of one of them breaking down as they were never designed for e-bikes.

By contrast, the Revonte CVT through inside the pedal hub. All that comes out are the pedals, and then the chainwheel and the chain. It’ll be easy to keep it clean, and you’ll only have to oil the chain a few times a year or you can even choose to use a belt drive.

Furthermore, we only use robust components that have stood the test of time, like spur gears and electric motor. This makes the system extremely durable (especially compared to some other CVTs on the market), while also bringing the total number of moving parts down to the level of a standard 3-speed hub gearbox.

And obviously, it’s a CVT. You’ll be able to maintain a comfy cadence of 60, no matter how fast you’re going, or how steeply you’re climbing.

Challenges we’ve faced

Of course, it’s not all honey and no sting with CVTs.

CVT systems – all CVT systems – are by nature a little less efficient than regular gearboxes. For that reason, they usually adopt a configuration illustrated below (artwork by yours truly).

On the left side there are the pedals. (Obviously!) The power coming in from the pedals is split between two parallel paths. The majority is led along the lower path – a highly-efficient conventional shaft plus standard gears. The remainder is led above, through the actual variable part. Here, speed can be traded for torque, or vice versa. Finally, the powers are combined in a kind of differential, and led into the rear wheel.

As a result, biking happens. And, by changing the transmission ratio of the variable part, we can change the total pedals-to-wheel ratio. Handy, isn’t it?

Also, by using this kind of a power-split approach, the losses in the variable part can be minimized. After all, a big part of the total power goes through a conventional transmission, which is very efficient.

However, the optimal split ratio depends heavily on many factors, such as bike speed, pedalling torque, preferred cadence, the configuration of the conventional-gear path, loss characteristics of the variable path…you get the point. For instance, a drivetrain optimized for steep uphill riding at 8 km/h loses some of its efficiency when cruising around the countryside at 25 km/h.

To complicate things further, all of the above was assuming no assist coming from the battery. Once we consider that, we have even more choices to make. For instance, should we put the assist right after the pedals? Immediately before the wheel? The lower path? The upper path? Or some combination of these? You get the point. And then there are all the dimensions of the individual gears and motor parts to consider.

So, how to wrap all these together?

Optimization

We begin by defining a representative drive cycle – an imaginary cycling trip with both mountainous terrain and urban crosswalks included. Everything, from the gradients to the speeds to the time spent in different environments, was adjusted to best represent a typical cycling behavior of the Revonte end-user. This drive cycle is then coupled to models representing the various components – gears and electric motors – to evaluate the system as a whole.

Of course, this alone doesn’t exactly help in choosing all the dozen parameters discussed above.

Luckily, we don’t have to make all the choices ourselves. Thanks to the advances in computers and in the science of optimization, we can now (and did!) automatically analyse tens of thousands of configurations to find the best fit for our application.

Since a CVT is a rather complex system (you are probably starting to see this by now), something called multi-objective optimization is used. True to its name, the ultimate goal of multi-objective optimization is to find the solution that is best in the all possible senses: the lightest, the most affordable, the most efficient.

But, as you’ll undoubtedly guess, such a solution almost never exists. For that reason, the realistic goal is finding the best possible trade-offs between different targets.

These can be nicely visualized as something called the Pareto front. Despite the weird name, the Pareto front is nothing more than a curve (or surface) visualizing the best trade-offs attainable.

An illustrative example between price and weight can be found below (NOT representative of final Revonte results – just an example). What you can read out of the curve is that a 3-kg design would cost a bit over 200 Euros, while the price of a 1-kg solution would be close to 600.

Like mentioned, that is just dummy data, but you certainly get the idea. Indeed, the main benefit of Pareto optimization is to let the designer make the final choice between different trade-offs. Like if the price would suddenly explode below 2 kg of weight, you probably wouldn’t want to go there.

But how does the optimization work?

Alright, this part is not directly related to the Revonte drivetrain itself. But, it’s still such interesting information that I decided to include it nevertheless.

Namely, how does the optimization work? Like, really work?

Well, we used a specific genetic algorithm (SPEA2 for those really detail-oriented). Genetic algorithms work by maintaining a large set of different designs – called a population of individuals. See where the name ‘genetic’ comes from already?

The actual optimization then happens by creating new generations of individuals from the previous one, based on simple rules utilizing random numbers. Like in Darwinian evolution, the best individuals are favored in the process. This way, each successive generation tends to get closer and closer to the right optimal design.

This process can be seen in the animation below, illustrating a very early-stage optimization run of a then-scrapped design. Each dot you see is an individual drivetrain design. To tell the different generations apart, the first ones are illustrated in blue while deep red is used for the final one.

As you can see, each generation represents slightly better designs – lower losses and lower maximum internal temperatures.


Conclusion

Phew, that was a long one. As a reward for making it this far, you can read the highlights in a convenient list:

  • A continuously variable transmission (CVT) always lets you ride with the best possible gear.
  • The Revonte drivetrain combines CVT with simplicity, robustness and low maintenance.
  • Actually designing the system was a daunting task in the beginning…
  • …but we made it, with some state-of-the-art optimization techniques. And lots of sweat.

Thank you for reading! Please comment, share, and get in touch!

Dr. Antti Lehikoinen

We are now Revonte

Revonte is creating a revolution in the e-bike technology

Freedom to innovate remains the heritage along our journey to make better e-bikes. Our new name underlines the evident new digital era movement in the e-bike industry. We are not happy to make small steps and call them innovations. We are one of the drivers of this industry to push things entirely onto a new level – make the digital revolution in e-bike electronics and services.

The story behind the name comes from Aurora Borealis, the Northern Lights, called Revontuli in the Finnish language. Electrically charged particles created by the solar wind forms an extraordinary light phenomenon in earth’s magnetosphere here at the northern latitudes nature. Name itself is a combination and word puzzle of those words, revolution and revontuli.

Similar to that, our personal “charge” comes from the dedication and passion for developing one of the greatest devices of mankind, e-bike, to its extreme. Making citizens life under the Revontuli better is our goal. We integrate the gearbox in the central motor, services to our system heart and diagnostics in our system soul. That makes lighting experience for every user.

from the CEO’s corner

Antero

Future of e-mobility

Eurobike 2018

Eurobike is now behind us, and slowly all the aftermath is done. It’s great to notice the ever-increasing interest on e-bikes and the effort manufacturers put into them. The whole industry seems to be moving forward and is slowly transforming from traditional bike manufacturing towards e-bikes with all the new possibilities.

Innovations keep gaining traction, and it’s great to see e-bike manufacturers embrace and test new models with new motor manufacturers – of which there seems to be more than ever. Competition is always good news for consumers and manufacturers alike since from hard competition innovations arise faster. E-bike market appears to be dividing into two segments of more heavy duty high-performance e-bikes and lighter e-bikes that are more focused on the riding experience.

Where is the future of e-bikes and e-mobility going?

It doesn’t take a genius to see that sharing economy is coming fast. Especially in the bicycle industry with companies growing at an enormous rate – unreachable for many traditional manufacturers. For example, Chinese bike sharing company MoBike (founded in January 2015) was sold for $2.7B to Meituan Dianping making it likely the most significant purchase ever in the bicycle industry.

It is no wonder that these bike sharing start-ups are gaining value so fast. Cities all over the world are growing, making the traffic ever increasingly more congested. For cities, these type of operators who provide their bikes to the town, free of charge, can feel like a blessing – which allows the technology providers to grow at tremendous speed.

However, to make the sharing solutions popular, it requires complex yet seamless integration between hardware and software. When e-bikes with recharging stations are added to this equation, the whole solution becomes even more complicated. At the moment electronic solutions in the market don’t allow manufacturers to provide shareable e-bikes easily.

While public bike sharing solutions keep growing and getting more and more popular, new solutions for transportation are on their way in the start-up garages and product development labs all over the world. New concepts of light electric vehicles keep popping up almost daily, some more sophisticated than others.

One of the more interesting ones is the German company Schaefflers Bio-Hybrid. What is so exciting about this type of vehicles is that in future they can solve the bottleneck of bike sharing – logistics. No matter if the bike sharing systems are stationless or fitted with stations the bikes need to be moved around via truck.

Four-wheeler vehicles like Bio-Hybrid can work around this problem with autonomous driving during peak hours to even the distribution. Sure autonomous capabilities still need a lot of work but as the AI evolves and car industry keeps working hard with self-driving cars, who knows how quickly this tech will be available for lighter use. In fact, hacker George Hotz’s company Comma AI has already made pretty good progress with their self-driving hardware that costs less than 1000 $. In case of Comma AI it hooks up with the car regular drivetrain, but light electric vehicles need a drivetrain that is flexible enough for innovations like this to evolve.

What could we learn from innovators in other industries?

Especially in the software industry, there has long been a mentality to fail fast – fail often. It is something that is slowly making its way to new fields. New innovations don’t evolve without failures and in the bicycle industry, especially with e-bikes, we should embrace ideology to test fast – fail fast in order to bring new features to the market quicker.

Most of the new technologies rely less and less on the actual hardware – meaning new features and enhancements can still be made even after the product is sold. One of the key examples here is Tesla with their Autopilot software, which is still work in progress. However, every Tesla that leaves the factory is equipped with the required hardware, so when the software is improved, it can be uploaded to the cars remotely. Another interesting example is Audis new project E-Tron that goes even further with over-the-air upgrades with features like new light patterns for headlights that can be bought later on.

In the e-bike industry, this is something that is not entirely taken advantage as of yet. Current systems can be upgraded via a Bluetooth or USB connection, but the full potential of software is yet to be harnessed. Especially as everyone is still so territorial about their products and ideas that it can take years for new features to hit the market.

Nonetheless, these are exciting times, and for sure the e-bike market will go through significant changes. We here at Revonte believe that new technology should be harnessed to its full power. It doesn’t just make our lives more convenient, but it also improves the user experience and whole progress of electric bikes.

 

Iiro Peltola,

Head of R&D

Who are we

Revonte in its current form was founded at the beginning of the year 2018. Revonte was originally a result of two e-bike enthusiasts coming together being fed up with the domination and restriction current electronic systems could provide. We strive on our passion and believe it should show in our corporate culture and in our products.

We both, me and Antero have worked inside the e-bike industry for years mainly on the reseller side gaining firsthand experience of customer needs. In his previous careers, Antero has been running successful industrial projects from start to finish giving him a great deal of expertise to work as our CEO. I come from a very different background as a millennial tech enthusiast and current mechanical engineer having experienced the rise of social media and service economy.

We both experienced the same limitation of current electronics in our previous product development projects – for me in public bike share project and for Antero in his innovation winning light electric vehicle project which led us to an idea to develop our own. Since then, we have iterated the idea with end users, bike manufacturers and service design experts to come up with what we believe to be a winning concept.

From the start, we have had a great pleasure to work with multiple start-up accelerator programs and great start-up culture here in our hometown Tampere. And it has truly shown – through these couple of months we have managed to iterate our product idea, raise private pre-seed funding, raise public funding, run through a feasibility study of the electronics and software, create initial product designs, design a prototype and strengthen our team. The latest addition to our team is Otto in the role of CTO – a successful serial entrepreneur with tens of years of experience in software development.

But a lot of our success is merit to our subcontractors. We have had the utmost success as well as a good luck with selecting the great partners to work with. For us, the fall of Nokia has been a great deal as it has left a huge amount of capable, brilliant and experienced engineering knowledge for us to make use of.

Our vision is to create a new revolutionary e-bike electronics that raise the bar in every segment from mechanical performance to embedded and cloud software. With the ideology we have learned from the software industry, we can provide new service models, earning methods and quicker product development which ultimately leads to better user experience and brand loyalty.

We believe that from here on we will only accelerate our pace – and we can guarantee You that we are working day and night to make that happen!

Iiro Peltola,

Head of R&D