You might have come across the term ‘slew rate’ while looking for the ideal sim racing wheel base. But what is torque slew rate, and why is it important for sim racing?
Torque slew rate measures the rate of change of a sim racing wheel base’s torque and is measured in Newton-meters per millisecond (Nm/ms). A wheel base with a higher slew rate gives you more responsiveness and clarity in force feedback, allowing for better control and precision on track.
As you explore various direct drive wheel base options, keep in mind that the ideal slew rate ultimately depends on your personal driving style. Some sim racers prefer a higher torque slew rate, while others may prefer a more subtle, smoother response from their wheel. I go through slew rate in more detail below.
Understanding Torque & Slew Rate
Before we go deeper on slew rate, we need to have an understanding of the most important aspect of a sim racing wheel base – the force feedback. Force feedback, or FFB, is an essential element of sim racing that helps create a realistic driving experience. It provides you with crucial information about what your car is experiencing, such as track conditions, grip levels, and overall vehicle dynamics.
Through force feedback, your wheel base applies torque to simulate these sensations.
Basics Of Torque
In sim racing, torque is the rotational force applied to your steering wheel. It is responsible for turning the wheel or resisting your hands as you apply a turning force. Torque is measured in Newton-meters (Nm).
Torque slew rate is a measure of the rate at which the level of torque can change.
You can think of slew rate as an indication of how quickly a wheel base can reach its maximum torque from a resting state. However, it’s actually a measure of how quickly it can go from any level of torque to another (e.g. from 0 Nm to 10 Nm or from 15 Nm to 20 Nm), although it may not be constant across the full torque range.
For example, the Simucube 2 Pro has a maximum torque of 25 Nm, and a torque slew rate of 8 Nm/ms. This means that torque levels should be able to go from a 0 Nm to 25 Nm within 3.125 milliseconds (25/8=3.125). Pretty quick!
Note: This calculation assumes that the slew rate is constant, which is not always the case in the real world. The slew rate might vary due to various factors, such as hardware limitations and software settings. Higher slew rates also aren’t always better, and I’ll discuss this in more detail soon.
Examples Of Direct Drive Slew Rates
To get an idea of the numbers in the sim racing world, let’s take a look at some wheel bases on the market from Asetek and Simucube (the 2 main manufacturers who willingly provide this information).
|Direct Drive Base||Max Torque (Nm)||Slew Rate (Nm/ms)|
|Simucube 2 Sport||17||4.8|
|Simucube 2 Pro||25||8.0|
|Simucube 2 Ultimate||32||9.5|
Note: These numbers are supplied by the manufacturers who each use their own methods for calculating them.
Importance Of Torque Slew Rate For Sim Racing Experience
Immersion & Realism
Your sim racing wheel base’s force feedback plays a crucial role in your perception of realism, and as well as peak torque, the torque slew rate is key.
With a higher slew rate, you’ll notice greater detail and accuracy in the force feedback, particularly when going over bumps, kerbs, and other track surface variations. As a result, you’ll gain a deeper understanding of how the car reacts to different driving scenarios, allowing you to fine-tune your performance and adapt your driving style.
This makes the entire experience more immersive and enjoyable.
At the other extreme, too low a slew rate can make your steering feel sloppy, less connected to the car, and less responsive to your inputs, reducing your sense of immersion and spoiling your racing experience.
Important Note: As I mentioned above, bigger numbers aren’t always better with slew rate. Going too high can make the steering feel overly harsh and unrealistic. I talk more about this (and how to avoid it) at the end of the article.
Driver’s Reaction Time
Another essential aspect of slew rate is its effect on your reaction time. Higher slew rates enable you to respond more swiftly to in-game events that require steering corrections.
Remember: The corrections required may also be throttle and brake corrections. Unlike in a real car, in a sim you can only sense car behavior using your eyes, ears, and the steering wheel, so force feedback simulates a range of sensations that provide you with key information.
In a competitive environment, this could be the difference between winning and losing.
Accuracy & Responsiveness
Torque slew rate affects the accuracy and responsiveness of your steering wheel’s FFB. To better understand this, consider how a steering system translates road feel and vehicle dynamics into the torque you feel in your hands.
In a real car, this process happens almost instantaneously, and having a similar response time in a sim racing setup greatly improves the overall experience.
A highly accurate and responsive steering system depends on multiple factors like:
- Motor capabilities: More powerful motors may provide higher torque slew rates, allowing quicker changes in force.
- Firmware and software settings: Ensure your sim racing software is properly configured to send the right torque signals to your wheel.
- Steering wheel mass: A lighter steering wheel can help reduce the overall inertia, leading to a more responsive FFB system.
By considering these aspects, you can optimize your slew rate to better sense changes in the car’s grip and the track surface, providing you with critical feedback and a more enjoyable sim racing experience.
Slew Rate In Sim Racing vs Real Driving
However, you’ll never truly match the feel of a real car on a real road. A real car’s steering wheel is connected directly to the front axle (via a system of rods and pinions), and therefore the tires on the road. This system can be thought of as ‘reactive’ as your steering wheel is reacting to what the tires are experiencing. When you provide steering input, clearly it’s the tires that then react to that input.
A real car’s steering wheel won’t have an associated slew rate figure, as this is a measure of how fast a motor can deliver changes in torque (it’s actually a term borrowed from electronics, as it’s typically used as a measure of how fast voltage or current changes).
While your car’s ability to respond to the environment and your inputs can definitely vary, this is a result of many other factors, one of which is steering responsiveness. However, a real car’s steering response is a result of yet many more factors. These include:
- The steering ratio
- Suspension geometry
- Tire characteristics
- The car’s weight distribution
- How fast you’re going
- Whether the car has power steering
A sim racing wheel base on the other hand can be thought of as ‘active.’ There is nothing physical affecting what your sim racing wheel is doing – it’s all data passed electronically to your wheel base and then to your hands. That’s why your sim racing wheel base needs a motor in the first place.
By definition then, your sim racing wheel must ‘actively’ create the feedback based on in-game signals. There are no ‘real’ road conditions to ‘react’ to, and so it can never feel 100% natural or as it would in a real car.
But would the average sim racer notice this? Probably not, unless you take the slew rate to the extremes of high or low.
Is A Higher Slew Rate Always Better?
A higher slew rate allows you to feel more detailed information about your car and the terrain you’re racing on. However, a higher slew rate may not always be ideal for every sim racer, and higher slew rates don’t necessarily lead to faster lap times.
One thing to consider is your skill level and racing preferences. If you’re new to sim racing or mainly use it for casual gaming, a higher torque slew rate might not make a significant difference to your overall experience, and in fact it could make it difficult to control your car at first due to how responsive it can be.
Also remember that a higher slew rate usually comes with a higher price tag, so you’ll need to balance your budget and preferences.
Higher Is Not Always Better
Having a higher slew rate also doesn’t necessarily guarantee a better sim racing experience. Factors such as the quality of the force feedback system, the overall build of your wheel base and wheel (including its size and weight), and the games you’re playing also play a crucial role in how you feel when racing.
Finally, it’s worth mentioning that different bases have different slew rates, even within a similar price range. While a higher slew rate may provide more detail, it’s essential to consider other factors and features that might better serve your sim racing preferences.
Don’t obsess over one feature, and instead try to have a holistic view on what the perfect direct drive wheel is for you.
Factors Affecting Torque Slew Rate
In general, better hardware provides a higher slew rate, which in turn results in a more immersive sim racing experience. Higher peak torque levels typically correlate with higher slew rates, as you can see in the table at the start of this article.
Software settings also influence the torque slew rate. Various sim racing games and wheel base management software provide options for adjusting the slew rate settings. Experiment with these settings to find the perfect balance for your driving style and preferences.
Keep the following points in mind when adjusting your software settings:
- Make sure to use game-specific settings for optimal compatibility with your hardware
- Higher slew rates may require more processing power, so ensure your PC can handle the increased demand
- Adjust settings incrementally to find the best performance for your wheel base and game combination
But how do you know that you’ve found that slew rate sweet spot?
How To Find The Ideal Slew Rate
To find the ideal torque slew rate for you, it’s essential to experiment with different settings. Start by adjusting the torque slew rate to a lower setting, then gradually increase it to see how it affects your driving performance and feel.
Pay attention to how much force you feel through the wheel and whether the feedback is responsive, allowing you to react quickly to changes on the track. As with racing in real life, a lot of it just comes down to that word – feel.
Different sim racing games and software may require different slew rate settings to achieve optimal performance. And many sim racing games have in-game settings where you can fine-tune force feedback parameters, including slew rate.
I recommend using a combination of in-game settings and your wheel base system settings to achieve the ideal balance for each specific game or simulator.
Just remember that personal preferences play a significant role, and there is no same ‘optimal’ setting for everyone, so experiment and find what works best for you!
Note: It’s important to consider your hardware specifications when adjusting the torque slew rate. Make sure your wheel base can handle the torque levels you’re setting, as exceeding the manufacturer’s recommendations can damage the hardware.
Below, I’ll explain how to adjust the slew rate for a few common racing disciplines.
Adjusting Slew Rate For Different Types Of Racing
For circuit racing (be it on a track or street circuit), you’ll want a torque slew rate that provides smooth and responsive force feedback. This allows you to feel the subtle changes in grip levels, road surfaces, and car behavior.
To achieve this, try setting your torque slew rate to a moderate value, which will strike a balance between responsiveness and smoothness.
Experiment with different values and remember that the ideal setting may vary depending on the specific car and track you are racing on.
Rally racing involves driving on various types of loose surfaces, which requires a different approach to torque slew rate settings. Rally cars tend to be livelier, and you’ll want to feel the constant shifts in grip and car balance.
So, consider increasing the torque slew rate to enhance the responsiveness of your force feedback. This will allow you to quickly react to changes in road conditions and better control your car through the unpredictable rally stages.
As with regular track racing, remember to adjust your settings to suit your personal preferences and the specific car and rally stage.
When it comes to drift racing, controlling your car’s oversteer is crucial. As a result, you’ll want a torque slew rate that offers immediacy in force feedback, allowing you to quickly correct your slides and maintain the desired angle.
To achieve this, you might want to set your torque slew rate to a higher value.
Note: Keep in mind that drift racing can be quite demanding on your sim racing hardware, so ensure that your settings are within the recommended limits of your equipment. Also be aware that setting your slew rate too high in these cases can make the car very snappy and difficult to handle if the maximum torque level is set to a high number.
Experimenting with different torque slew rate settings for each racing scenario will help you find the perfect balance that suits your driving style and enhances your sim racing experience. Don’t be afraid to refine your settings as you gain more experience and get a better feel for what works best in various situations.
Common Challenges & Solutions In Adjusting Torque Slew Rate
Challenge 1: Dealing With Inconsistent Force Feedback
You may experience inconsistent force feedback in your setup, which could make it difficult to control your car.
One solution is to adjust the slew rate lower to ensure smoother and more consistent FFB. Experiment with different settings to achieve the right balance between responsiveness and stability.
Some games may have specific force feedback settings that you can fine-tune for better performance.
Challenge 2: Managing Wheel Oscillations
Wheel oscillations can occur when the force feedback is too strong or too sensitive, leading to an unpleasant and unrealistic driving experience.
Adjust the torque slew rate to lower levels to help reduce these oscillations. Also consider reducing the overall force feedback strength in the game settings and/or your wheel base software.
Challenge 3: Understanding Motor & Wheel Base Limits
The actual achievable slew rate depends on the limits of the motor itself, the wheel base’s firmware limits, and any specific game’s feedback limits. It’s essential to understand these limitations to make the most effective adjustments to your torque slew rate.
Refer to the documentation of your wheel base for recommended guidelines and values (a lot of us may feel too proud to check the instructions, but please, do it!).
Challenge 4: Adjusting For Wheel Weight & Diameter
Another factor to consider when adjusting torque slew rate is the combined weight and diameter of your wheel and button box.
If possible, try using a lighter wheel setup or experiment with different wheel sizes to find what works best for your setup.
Finally, let’s see what Asetek’s Andreas Windfeldt has to say about torque slew rate, before I give my final thoughts on the concept.
Q&A With Andreas Windfeldt From Asetek
I go to a lot of sim racing events, and one person I have met a couple of times is Andreas Windfeldt who works at Asetek.
The second time I met him, he was boasting about the slew rates of Asetek’s wheel bases compared to their competitors, so I had to ask him a few questions!
RO: How do you measure the slew rate of your wheel bases?
AW: We’re measuring our wheel base’s performance using rotating torque sensors with non-contact transmission.
RO: How does Asetek measure up vs the competition?
AW: We have test machines where we benchmark our own DD Wheel bases against the competitors. We can’t share test data from other brands, but let’s just say our customers will be very pleased with the results! 😉
RO: How much of a priority is slew rate for Asetek’s wheel bases?
AW: It’s a big priority because we want to provide the sim community with outstanding products that can give them the feeling of driving a real race car in their living rooms. Slew rate is a significant factor in delivering those products. The faster the torque delivers, the more detailed feedback the user will experience.
RO: Can you tell me about Asetek – what was the company’s history before recently entering sim racing?
AW: The company was officially founded in 2000 by a young, ambitious toolmaker who also studied for an engineering degree. His name is André Eriksen who is still today the CEO of the company. He invented a cooling solution that could freeze the CPU down to -40 degrees Celsius, landing many headlines worldwide.
After a few years, the company invented what is today known as the AIO liquid cooler, which is a maintenance-free closed-loop system. We have shipped more than 10 million of these today and continue to do so.
RO: So if business was going so well, why did you enter sim racing?
AW: We had been looking for an additional business within the gaming industry for years where we could sell directly to consumers (B2C). André Eriksen is a big racing enthusiast who has also been driving himself, not to mention his son, a former GT3, F3, and currently LMP3 driver.
They had previously been experiencing difficulties assembling a rig with products from various brands, and they also missed the real racing feel so that you could practice for a race from home and actually get something out of it.
We started looking at our company’s resources. Because we had +20 years in Mechatronics and an already established supply chain and R&D department, we could get started right away to create a complete ecosystem with ease of use in mind, and a true-to-life racing feel.
Also, due to our mass-production experience, we could manufacture very high-end equipment for a mainstream price tag so that more people could afford the “real deal.”
RO: What are Asetek’s ambitions within this niche?
AW: We aim to become the market’s preferred one-stop sim racing manufacturer where customers can buy everything they need for their rigs, while allowing customers to upgrade products as they improve.
RO: Thanks Andreas!
What I’m about to say may go slightly against ‘conventional wisdom’…
While I think that slew rate is important, I also think that for most direct drive wheels on the market, slew rate is starting to turn into a vanity metric.
When using the Simucube 2 Sport, I tend to run the base between 0.5 Nm/ms and 3.0 Nm/ms, depending on the simulator software and the type of racing I am engaging in. You’ll notice that is substantially lower than the 4.8 Nm/ms maximum of this wheel base.
Maybe higher-level sim racers can absolutely notice differences beyond 3 Nm/ms, but after asking others who also have some years of experience, I hear similar opinions from them too.
Part of the problem of setting the slew rate above 3 Nm/ms for me is that the force feedback starts to feel too harsh and jerky (and I’m talking about things like bumps and kerbs, not just the obvious crash scenario – where your hands should be off the wheel anyway at such high torque levels).
I recommend you scale your slew rate setting up in proportion with the amount of max torque you set. This way, as you get comfortable setting peak torque at higher levels, the variations in FFB should ‘feel’ similar to when you were racing with lower levels of torque.
This leads me to say that, assuming torque slew rates are now at levels that are good enough for most sim racers, peak torque should be a more important factor in your buying decision. Clearly this will vary by manufacturer, and not all brands share slew rate numbers yet, but I still recommend looking at the peak torque figure as more important when buying a sim racing wheel base.
From everything I’ve written above, we can see that torque slew rate plays an important role for your sim racing experience. But, for me at least, there is a limit to its benefits.
I would recommend first-time DD wheel base buyers to consider the Asetek Forte (18 Nm max torque, 6.7 Nm/ms slew rate) or the Simucube 2 Sport (17 Nm max torque, 4.8 Nm/ms slew rate), while the Simucube 2 Pro (25 Nm max torque, 8.0 Nm/ms slew rate) is a good upgrade option.
Just keep in mind that while higher slew rates sound great, it’s essential to balance other factors, such as cost and compatibility with your current sim racing setup.
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