„PERFORMANCE WHICH AMAZES ENTHUSIASTS AND ATHLETES ALIKE.”
WHY IS THE SACHS RS SO STRONG?
The E-Mountain Bike helped this electric engineer by trade back to an active lifestyle, and changed his conception that E-Bikes are for commuters only. Today, he rides an E-Mountain Bike multiple times a week and seeks the challenge of hill-climbs in rough terrain. As an experienced E-Mountain Biker, the Director of Sales for Sachs Micro Mobility had the opportunity to contribute his experience in the development of the new SACHS RS. Jörg Schmidt, born in Odenwald, Germany tells us the story of how this powerhouse-motor came to be.
How is the back, Mr Schmidt?
Thanks, besides the trying times it is much better. It is also thanks to a lot of E-biking.
How often do you currently get out to ride your E-Mountain Bike?
Once or twice a week. Often in the evenings after work I meet with friends for a night ride. That is the best way to balance work; we sweat and laugh. Without an E-Mountain Bike, I would not be able to do things like that here in the Odenwald in such a simple way anymore. Just outside my door there is a 400m elevation gain.
This was a challenge with the Mountain Bike, but with the first E-bike the fun returned. Today with the SACHS RS-Bike it is another dimension.
Can you describe this dimension a bit closer?
In the past with small batteries and weaker motors you reached the peak performance and range limit fairly quickly. Therefore, riders would ride cautiously, or it would be a short ride.
The 110 Nm of torque allow me today to have much more fun in the effective, middle performance area. This works the same as for athletes: If you have a maximum pulse of 175 beats per minute, you have less endurance at a constant 155 beats per minute than a more trained athlete with a maximum pulse of 195 beats per minute. The SACHS RS is stronger and therefore can offer a much more elastic performance in sportive environments. The power is converted in a more effective way and this yields much more range. Downhill has always been fun, but now also technically demanding uphill trails bring a kick of that same joy. Performance and fun at 100%.
How has SACHS doped the motor? Were you involved in the development?
The development was focused on our customers and their requirements. I was lucky to be one of the customers, that could write their requirements on a long list. This list was then put into practice by our development team step by step.
Regarding the topic of “doping”: The motor is not doped, otherwise it would not last for long. We have utilized a different approach. How can we develop a motor and a system, which provides high power without performance loss already at a low cadence? The lower pedaling cadence is an important component, as many e-Mountain Bikers do not have a sport-bicycle background. The most important for us: How could we make our system robust to withstand harsh conditions in the city as well as in alpine territory?
What do those solutions look like?
We looked where we could find electric motors that provided instant high-power output and were able to sustain this output for an extended period of time. We found the basis for our motor in the power tool segment. The electric motor in the SACHS RS stems from professional power drilling machines and like they are used on large construction environments.
The second approach was to develop a robust gearbox. It is a helically toothed planet gearbox, which is completely supported by roller bearings. These are also found in wind-mills or utility vehicles. We accepted some weight penalty to offer superior quality and durability.
The third and most important point was cooling. The stator of the electric motor is directly molded into the motor housing with a heat-conducting compound. That is where most of the heat is generated by the power, which needs to be conducted away. The current models in the market often have the stator and the coil are often only surrounded by air which perfectly insulates the heat. This is not wanted at all, since we would like to dissipate the heat outside as quickly as possible.
You spoke about city and sportive E-Moutain Bikes as application fields for the motor. This is easily imaginable in for mountain bikes, but how does it work in the city?
In the city E-bike rides have different challenges, however they pose similar challenges to the system as alpine terrain. Lots of traffic lights, lots of accelerating, often in a gear that is either too high or completely incorrect. Additionally, the bikes are packed with kids or groceries, but are still required to move in an agile way. Here SACHS RS provides maximal power output already at a low pedal cadence of 40-60 rpm. The motor is forgiving to “rider errors” though its power and setting and provides more safety to the rider. Cargo bikes benefit especially from these properties. Also, inexperienced bikers can gain more courage and safety on challenging root-trails. Missing muscle-strength and riding technique is compensated by the SACHS RS.
Does that much power not require a lot of energy?
If you are driving full-speed, the user will always require a lot of energy. This is the same for an e-bike and a car.
What makes the difference is the overall concept: The peak power results from the design of the motor – the goal was not to develop a 110 Nm motor.
As the motor does provide such high peak power rating, most riding happens in the middle performance sector of the motor, even if it feels like full speed for the driver. Therefore, the system is efficient and yields high range ratings. This is confirmed by all our tests, also with top athletes. We deliberately chose athletes who are able to produce high output wattage for long times. Almost 2000 meters in altitude with medium to high power by the biker were the result. Nevertheless, the motor stays in the ‘green’ performance area. The riders came back with the brightest of smiles.
Two controllers for the motor and battery finetune motor, battery and gearbox for a perfect interaction. The motor controller checks the power, rpm, sensors and temperature. The battery management system safeguards the battery from damage. The cells need to monitored much more closely than for a lead-acid battery normally found in a car. Additionally, the system generates all important data such as battery charging state and range for the driver.
Did you get fitter with the SACHS RS?
That depends on how you define ‘fitter’. I would rather say, I am riding my bike much more often, and I enjoy it every time. Nowadays, I can ride technically demanding trails thanks to the SACHS RS, even if my body is not feeling as fit as it did some years ago. This is important to me, to do the night-rides together with my friends. In the ‘trail-battle’ I can only keep up, if I am riding the appropriate E-bike with the corresponding support level. This time on the bikes not only helps my body stay in shape, but also offers balance for mind, mental strength and motivation.
In summary: Fitness and performance increase on a whole new level.