Direct Drive Explained: Torque, Clipping, Encoders and Slew Rate
Source video: Serial Driver — Direct Drive explained by Simucube co-founder and CTO Tero Kontkanen
The French Simracer verdict in 30 seconds
Direct Drive improves force feedback by removing the belt or gearbox between the motor and steering wheel, but maximum torque is only one part of the result. A good wheelbase also needs useful headroom, an accurate encoder, responsive motor control, well-designed software, a rigid Quick Release and a stable cockpit. Choose the complete signal chain—not the largest Nm figure.
What is a Direct Drive wheelbase?
In a Direct Drive wheelbase, the motor, encoder and control electronics act directly on the shaft that drives the steering wheel. Belt-driven and gear-driven systems add a transmission between the motor and the driver. That transmission can introduce friction, play, flexibility or a slower response.
Tero Kontkanen describes the central objective as transparency. A good wheelbase should behave like a clear window onto the simulator’s physics. It does not create the information generated by the game; its job is to reproduce it without adding unwanted behaviour.
- Fewer mechanical intermediaries: the motor acts directly on the steering wheel.
- Cleaner response: load changes can be transmitted more quickly.
- Better readability: grip changes, weight transfer and surface texture become easier to distinguish when the whole system is well controlled.
- More available torque: motors designed for Direct Drive can provide more headroom than compact traditional wheelbases.
Direct Drive architecture is not an automatic guarantee of quality. Two wheelbases with the same maximum torque can feel very different because of their motor, encoder, electronics, software and ability to remain consistent.
No belt or gearbox between motor and steering wheel
Preserves force variations before clipping
Slew rate defines how quickly torque can change
Motor, encoder, software, Quick Release and cockpit
Maximum torque, sustained torque and clipping
Torque, measured in newton metres (Nm), represents the rotational force a wheelbase can produce. It is the most visible number on a specification sheet, but it only answers part of the question.
Why torque headroom matters
Signal path
Headroom keeps useful variations below the wheelbase limit.
The simulator continuously calculates the torque it wants to send. If that request exceeds the configured or available capacity of the wheelbase, the signal reaches a ceiling. This is clipping. The steering wheel still feels heavy, but further variations in the signal disappear. A bump, grip loss or weight transfer can be hidden inside that saturation.
Torque headroom is therefore not primarily about driving with permanently heavy steering. It preserves detail during peaks. There is no universal ideal output: the right level depends on the simulated car, game, steering wheel diameter, driving preference and cockpit rigidity.
Peak torque does not tell the whole story
Torque versus velocity
Maximum torque alone does not describe behaviour across the complete motor-speed range.
A wheelbase may advertise a maximum torque that it cannot sustain indefinitely. How long it can maintain that output depends on the motor, power supply, cooling and controller design. According to Tero Kontkanen, a properly designed wheelbase should not reduce torque during normal driving; the risk increases when it is operated continuously near its limit.
It is therefore important to distinguish:
- maximum torque, available during peaks;
- sustained output, describing stability over time;
- headroom before clipping, which helps preserve information;
- response quality, which cannot be reduced to an Nm figure.
What matters beyond Nm?
| Criterion | What it measures | What the driver feels |
|---|---|---|
| Maximum torque | Maximum rotational force | Steering weight and headroom before clipping |
| Cogging | Natural magnetic detents in the motor | Low-speed smoothness and rotation quality |
| Encoder | Shaft angle and movement | Control accuracy, velocity and acceleration calculation |
| Slew rate | How quickly torque can change | Response to impacts and sudden load changes |
| Refresh rate | How often the signal is updated | Temporal detail and reconstruction requirements |
| Software and filters | Signal processing and stabilisation | Balance between detail, natural response, noise and stability |
Cogging: the motor’s magnetic detents
Cogging describes torque variations that can be felt when turning certain motors, particularly while the wheelbase is switched off. Rotation can feel as though it passes through a series of small steps. A compensation algorithm can substantially reduce this behaviour while the base is powered, but its effectiveness depends on speed and response bandwidth.
Cogging should not be judged only with the wheelbase switched off. What matters is the result while driving: smooth low-speed movement, clean vibration and the absence of unwanted grain or notchy behaviour.
Encoders: resolution is only part of the story
The encoder measures shaft angle. Higher resolution can theoretically track finer movements. Its purpose is not to make the driver feel millions of individual “steps”; the electronics use these measurements to calculate position, velocity and acceleration before controlling the motor.
In the interview, Tero Kontkanen considers approximately 20-bit resolution sufficient in practice when used well. More importantly, a high bit count alone does not prove that the signal is better. Real accuracy, noise, latency, filtering and sensor technology also matter. He particularly discusses possible differences between optical and magnetic encoders.
Encoder information chain
A cleaner position signal reduces the amount of corrective filtering required.
Slew rate: how quickly torque changes
Slew rate describes how much torque can change over a given time, often expressed in Nm/ms. It is not maximum power. A strong wheelbase may still change torque less rapidly than another model.
If slew rate is too low to follow the requested signal, fast transitions are rounded or delayed. The driver may lose part of the impact from a kerb, collision or sudden load change. A very fast response can also feel aggressive, which is why some wheelbase software allows users to limit it according to the game and their preferences.
Slew rate
A low slew rate rounds the fastest transitions; a very high one can feel aggressive if left unfiltered.
Refresh rate: the game and wheelbase work at different speeds
The video separates the game’s output rate — usually much lower — from the internal control rate of the wheelbase electronics. A low game rate creates a staircase-like signal. The wheelbase must reconstruct and smooth that signal without introducing perceptible delay.
Too little smoothing can create noise and roughness. Too much can produce a soft or rubbery response. A good algorithm must find a clean path between those two problems.
Signal reconstruction
The objective is to smooth the steps without adding a perceptible delay.
Why software matters as much as the motor
A good motor controlled by weak software will not produce good FFB. The reverse is equally true: a sophisticated algorithm cannot erase every limitation of the motor, encoder or power supply. Final quality is determined by the weakest link.
Wheelbase software commonly provides several groups of settings:
- reconstruction or smoothing: reduces the steps in the game signal;
- damping: slows rapid movement and stabilises the steering wheel;
- friction: adds more constant resistance to rotation;
- slew rate limit: reduces the aggression of fast torque changes;
- overall force: defines the capacity available from the wheelbase.
How should a Direct Drive wheelbase be configured?
Setup advice: begin with low filter values, monitor clipping, then add only enough reconstruction, damping and friction to obtain a stable response without hiding useful detail.
The video recommends starting with low filter values and adding only what is needed. The correct settings depend on the simulator because games do not all transmit FFB at the same rate or with the same information density.
- Choose an overall force compatible with your cockpit and safety requirements.
- Adjust in-game gain while monitoring clipping.
- Add reconstruction progressively if the signal feels grainy.
- Use damping and friction to stabilise the steering wheel without hiding detail.
- Test with a familiar car and circuit before changing several settings at once.
Running the wheelbase at 100% is not an absolute rule. Torque headroom helps avoid clipping, but a base-side limit can also protect the driver from violent spikes during a virtual crash. The aim is to retain enough headroom for useful information without exceeding a manageable output.
Quick Release and cockpit: the mechanical links
The Quick Release should behave like a rigid connection: no play, no rattling and as little flex as possible. Its mass, concentrated close to the axis, is generally less important than its rigidity. A larger or heavier steering wheel changes the perceived inertia more significantly.
The cockpit plays the same role on a larger scale. A flexible frame absorbs movement and may resonate under fast effects. A capable Direct Drive wheelbase mounted on an unstable support cannot reproduce its full potential. The budget should therefore be balanced between the wheelbase, steering wheel, pedals and a suitable cockpit.
Can a better Direct Drive wheelbase make you faster?
Not automatically. Fast drivers can produce excellent lap times with simpler equipment. A more precise wheelbase can nevertheless make the car easier to read and help with repeatability and reference building. Tero Kontkanen explains that drivers who use Simracing for motorsport training place significant value on FFB quality and consistency.
For recreational use or a first setup, the most powerful model is not necessarily the best choice. A balanced, well-configured Direct Drive wheelbase mounted on a rigid cockpit often delivers more value than a simple race for maximum torque.
How should you choose a Direct Drive wheelbase?
Before comparing specification sheets, ask these questions:
- How much torque can I use comfortably and safely?
- Does the wheelbase retain enough headroom to avoid clipping?
- What is known about its motor, cogging and encoder?
- Does the software provide clear settings, profiles and regular updates?
- Does the Quick Release and steering wheel ecosystem suit my setup?
- Can my cockpit accept the mounting system and forces involved?
- Is compatibility with my PC, console and chosen games confirmed?
To compare the current range, browse our Direct Drive wheelbases and our Direct Drive database. You can also explore the Simucube, Simagic, Fanatec, MOZA Racing, VNM and Conspit ranges directly.
Benefits and limits to keep in perspective
What Direct Drive can improve
- Mechanical transparency
- Torque headroom before clipping
- Response to rapid load changes
- Grip and weight-transfer readability
- Consistency when the system is well tuned
What maximum torque cannot prove
- Encoder accuracy and latency
- Software and filter quality
- Sustained output over time
- Quick Release rigidity
- Suitability for your cockpit and games
Compare Direct Drive wheelbases with the right criteria
Use torque as one part of the decision, then check software, encoder, ecosystem, mounting and cockpit rigidity.
The French Simracer verdict
Do not choose a Direct Drive wheelbase from maximum torque alone. Nm determines force and available headroom, but FFB fidelity also depends on the motor, encoder, slew rate, algorithm, filters, Quick Release and cockpit.
The right wheelbase preserves detail without clipping, responds accurately, remains consistent and genuinely fits the rest of the setup. That complete chain — from the simulator to the driver’s hands — creates the transparency described by Tero Kontkanen.
Direct Drive FAQ
What is the difference between Direct Drive and belt drive?
A Direct Drive wheelbase connects the motor directly to the steering wheel shaft. A belt-driven base adds a transmission between them. Direct Drive therefore reduces play, friction and deformation introduced by that transmission.
How many Nm does a Direct Drive wheelbase need?
There is no universal ideal figure. The wheelbase needs enough torque headroom to avoid clipping without exceeding what the driver and cockpit can manage. The car, game and steering wheel diameter also change the perceived output.
Does more torque mean more detail?
Torque headroom can preserve detail during peaks, but two equally powerful wheelbases may feel different. Motor design, encoder performance, slew rate and software processing are also decisive.
What is Direct Drive cogging?
Cogging is a torque variation caused by the motor’s magnetic positions and can feel like small detents. Software can compensate for it while the wheelbase is powered, so the result should be judged while driving rather than only with the base switched off.
Should a Direct Drive wheelbase be set to 100%?
Not necessarily. There should be enough capacity to avoid clipping, while retaining an appropriate safety limit. In-game gain and maximum wheelbase force must be configured together.
Is a rigid cockpit necessary?
It is strongly recommended. Flex and resonance absorb or distort part of the FFB. The mounting system must be compatible with the wheelbase and suitable for the forces that will actually be used.
Technical explanations and diagrams are attributed to Tero Kontkanen in Serial Driver’s source video. The article reorganises and paraphrases the interview; paraphrases are not presented as direct quotations.