January 16, 2015

AccuForce Review

The most anticipated wheel of the year comes with a warning...

First Time Use Of The SimXperience AccuForce Steering System may cause serious disbelief and outrage when you realize what you've been missing out on all of these years.

Yes, consider yourself warned if you've never experienced the feel of a direct drive wheel before. When you realize what you've been missing in all of your years of simracing from not having force feedback delivered to you via direct drive, the amount of filth that will come out of your mouth will surprise even your pets.

Before I get into how and why that is, let's take a look on what you actually get.

Packaging & Assembly

The SimXperience AccuForce Pro Simulation Steering System arrives in a fairly heavy box. 35lbs to be exact!  Each component is packaged neatly and separately. Included are the base unit, a suede 320mm wheel rim, a button box with paddle shifters, and a standalone controller box for housing all of the wheels electronics and power supply.  The wheel I received was a pre-production beta unit, and despite that all of its components oozed with quality.
Assembly was fairly straightforward. A single cable connected the wheel to the controller box, and a USB cable connected the controller box to the PC. The controller box plugged directly into the power via a standard PC power cable. As per the instructions, I had to be mindful to route my cables and place the controller box away from all of my other cables and PC.  SimXperience assured me this was a precautionary step to avoid any electrical interference. They explained that even though all of the cables of the wheel assembly were shielded up to spec, they still make the recommendation because they can't guarantee that other cables or devices located near the wheel would be.

Base & Mounting

In addition to being beautiful, the all metal base motor casing is also functional. It's designed to act as a heat sink for the motor, conceal any internal wiring, and is pre-drilled on the bottom for rig mounting with 8 M6 bolt holes.
On the rear side, the base features 3 USB ports, what looks like a telephone jack, and three other pin ports.  The USB ports allow you to plug devices as if they were plugged into the PC. Any devices plugged into those ports do not get recognized as being part of the wheel, but as separate devices. It is unclear what the telephone jack is for and the other ports, but most likely intended for 3rd party accessories.

The base also features a custom designed, industrial grade motor, in a direct drive configuration.  Direct drive means that the steering wheel is mounted directly onto the output shaft of the motor inside the base unit. There are no reduction systems made of gears or belts between the motor and the wheel.  It's simply a 1:1 ratio between the output of the motor and the steering wheel.

Mounting requires planning and caution. The entire base unit is composed of pretty much all motor, and weighs nearly 21lbs.  It is very heavy, and should certainly not be handled like a toy. I had to be very careful when mounting it as the weight of the base was downright dangerous. Dropping it would have caused damage to my floor! Dropping it on my feet would have ensured a visit to the emergency room!

The base is completely flat, so mounting at an angle requires that the surface to which it's bolted to be adjustable or use some sort of angled bracket. SimXperience has mentioned that they will soon provide wedge mounting brackets which can be purchased separately for this purpose. My beta unit did not come with a bracket, but I was able to finagle the bracket from my old Fanatec wheel so that I could mount it at an angle to my Obutto Ozone rig, which doesn't feature an adjustable wheel tray.

It is imperative that the wheel be mounted to a very solid frame. SimXperience explicitly states that the frame should withstand up to 16Nm of torque.  How you would ensure and measure that precisely is a little beyond me, but I would encourage you to think metal, not wood.  Mounting to a desk or to a rickety rig may not do the trick when driving the wheel in serious competition.  Not so much because the wheel will generate torque that will break a desk, but because vibrations with peak values can have a jack-hammer effect and may shake things pretty violently.

Quick Release

The steering wheel and its button box attach to the base via a standard quick release system that is found on many modern race cars. The hub makes it very easy to attach and detach the wheel. When attaching the wheel, its position relative to the base can be arbitrary. You simply push in the wheel and rotate it against the base hub until the locking bearings click into their groves.  Most of the time if you just aim more or less correctly, the wheel will lock in without having to twist it into place. The groves follow a unique pattern, so the wheel always attaches correctly.

There are no pins to align as the electrical connections on the base hub are flush.  They are met by pins on the wheel's hub which are spring loaded to always ensure a tight connection.

Detaching is even easier. You simply unlock the hub by pulling onto the QR handles on the wheel's side, and the wheel becomes free to be pulled off.  There is no need to pull hard on the wheel when detaching it, which is great for keeping all of your teeth intact as the wheel doesn't suddenly fly toward your face when it disconnects!

One of the coolest features of the quick release hub is that it contains an electrical slip ring on the side of the base. This allows the wheel to rotate infinitely without having wires that twist. The slip ring is a silicone disk board with circular gold contacts on its face which allow connectors on the rotating part of the hub to slide around against it.  This unique feature allows you to configure the wheel to rotate within virtually any angle range. The wheel does make a subtle hissing noise when rotating it, but the noise obviously doesn't come from any gear drives or belts, but rather from the friction of the electrical contacts against the slip ring inside the hub.

Button Box & Paddle Shifters


The button box in this Pro version already comes mounted to the wheel. It features 12 push buttons, color coded in red and black. The buttons can be adjusted to an extent, which allows for the hub to accommodate a variety of other wheel rims. The hub is also extensible, which allows 3rd party vendors and modders to let you install more buttons, switches, or rotary encoders. When the wheel is connected to the PC, 48 buttons in total get recognized by the default windows driver even though only 15 are actually used. A neat touch to the center cap of the wheel is that it functions as a 13th button on the button box. Honk, honk!

Attached to the rear of the the button box are the paddle shifters. They are made from genuine carbon fiber and give the wheel a really sporty look. The paddle shifters engage in a very precise manner, giving great tactile feedback and confidence. They are extremely easy to adjust via two bolts located on the back side of the paddle shift assembly. The bolts adjust the distance from the wheel and amount of travel of the paddles, and are easy enough to twist with your fingers. They are threaded through a spring to ensure that the bolts don't come lose during heavy wheel vibrations.

Pro Steering Wheel

The steering wheel that is included with this pro version is a genuine 320mm 3 spoke all metal rim suitable for a real race car.

It is wrapped in high quality thick suede that is stitched and trimmed to perfection. There are absolutely no lose ends or flaps that get caught in your fingers.  The rear side of the wheel is ribbed for your fingers in the 12, 3, and 9 o'clock positions to give you even extra grip.  It also features a red leather centering marker. Unlike the synthetic Alcantara material found in many modern luxury automobiles, the suede covering feels quite natural and dry to the hand. Even after extended use. 

The only downside with my beta unit was that for the first couple of days, the suede shed and turned my hands black.  SimXperience told me that this was expected and recommended that I use gloves. My gloves also turned black unfortunately. I am not sure if this is the case with the MOMO wheel, which is an option for the MOMO edition of the AccuForce wheel, or the final production units. However, after a few days of use, the wheel stopped shedding completely and is now perfectly normal and doesn't stain my hands.

Since the suede is really grippy, I highly recommend using gloves when driving the wheel with higher forces. During slides, when the wheel starts to correct from aligning torque, the speed of the wheel may end up catching the skin between your thumb and index finger, flipping your hand over, causing a minor skin burn. I guess there is a reason why real race car drivers wear gloves in addition to having added fire protection.

Rotation & Bump Stops

When the unit is powered off, the wheel rotates quite smoothly around the base. The lack of internal resistance offered by this direct drive system is clearly apparent.  It's as if the wheel rotates freely around glass bearings.

When powering on the unit for the first time, after a few seconds, the wheel performs a calibration step just like most other wheels on the market. It rotates to the left and right for a total of 900 degrees and centers itself. It does it at a seemingly leisurely pace without giving you fear that it will chop your hands off even though the motor has enough juice to do so.

The wheel can rotate infinitely around its base and, via the driver software, can allow for virtually any rotation angle. Setting the wheel to over 2,000 degrees of rotation range for your latest bus driving simulator is not an issue. Or perhaps if you're playing some esoteric door valve simulator, you can adjust it to as much as 8,000 degrees, or more! Whatever the case may be, there is more than enough rotation angle to accommodate pretty much any virtual steering wheel system.

The range of the wheel is bounded by the wheel's force feedback, which simulates bump stops.  The hardness level of the bump stops is also adjustable via the driver software.  The settings allow you to have anywhere from a really hard stop, where the wheel will simply bounce off the stop as if it hit rock, to a much more dampened stop as if the wheel was stopped by some mushy substance. Pushing past the stops is not quite easy, but also not quite hard.  With both arms, the applied max torque of the wheel can be overcome. When released, the wheel rotates back into its range smoothly without trying to saw your fingers off.

Here we go...

The Feel

For my very first test, I fired up iRacing, choosing the C6R at Sebring. I specifically chose a bumpy track and a car I've always struggled with to control at the limit, to see if this wheel was indeed the holy grail I've been after all these years.  I am ashamed to quote the first words that came out of my mouth in reaction to what I felt from the wheel driving out of the pit lane. 

Never in my 17 years of sim racing had I felt such detail, such clarity, and such precise feedback from any sim or game. It was as if I had witnessed 3D HD video for the first time after only watching black and white TV! I couldn't believe there was this much detail available to deliver and with such crystal clear clarity. When driving over curbs, it was as if I could tell whether or not I was driving over the white or blue patches. I felt like all of these years I had been betrayed, lied to, and sold to absolute nonsense with any of the other wheels I've owned. It was incredible. It was unbelievable. It was simply ridiculous! 

This wheel doesn't have any auxiliary motors to cause vibration; it's just a single motor. Any vibration effects are just genuine wheel movements at a varying levels of frequency. An interesting thing about the vibration frequencies is that you can feel incredibly high levels. The wheel simply keeps on vibrating until the frequencies relay that very weird buzzing feel into your hands. Where it's not quite vibrating, but you can feel shivers going through your arms. Vibration frequencies do not simply stop or disappear as they get higher, they just keeps on getting higher, and higher, and higher until you simply let go because your hands start to feel weird.

One of the most captivating bits about the FFB from this wheel was the ability to feel the tiniest of forces.  The very low, rumbly, twitchy forces as you drive over bumpy surfaces.  You know, the ones where you needed a bunch of Min Force in iRacing just to get your wheel to vibrate slightly on.

At Daytona, there are two dark patches on the racing surface in the final corners leading onto the front stretch. It really surprised me that through the wheel I was able to feel driving over them. The first patch came through as a very subtle and long flat hump, and the second a much shorter, but slightly more subtle bump. What was even more amazing was that I was able to feel which wheel went over which bump. Both wheels over the first patch, and the right wheel over the second. To me, this really highlighted the laser scanned surface of the iRacing tracks, as it allowed me to feel far more subtle differences in the racing surface.

When going into a corner, the force of the wheel would ramp up significantly, but the feedback was still very precise and detailed.  The smoothness of the wheel didn't let you feel as if you were fighting the wheel's feedback, but rather fighting the car you were driving.  Absolutely no cogging and no notchy feeling, just honest, precise, and raw feedback from the sim. 

No matter how high the forces got, there was always detail, detail, and more detail to be felt. However, when driving over a smooth surface, the sim gave almost no feedback, which made the wheel feel dead and smooth as glass. When hitting a curb, the wheel gave sharp and precise jolts. Specifically curbs that rumbled gave off the rumbling in the wheel at a high and well defined frequency. This seems to very well highlight when the simulation had force feedback to relay. 

The detail was so good that the force feedback from the game seemed inadequate. To explain what I mean by that, imagine viewing a low resolution image on a really high resolution display such that you can see all of the individual pixel boundaries on the image.  It was very clear when the sim gave feedback, how much, and how often even at the highest frequency.

Catching Slides

The rumors of direct drive wheels making slides easier to catch are true. Because of the high detailed information this wheel delivers, it's not only a lot easier to know when you're starting to lose grip, but the quickness, the low resistance, and low inertia of the wheel allow you to catch and correct a slide far earlier than before.

I remember the days when I used to try drifting around in LFS. I always struggled despite it being a sim where this was fairly easy to do, and was never quite good at it. Maybe I never had the fast reaction time required, or maybe I never quite got how to do it right. Plus, I always felt that some cars were better for it than others. Jumping into the FZ50, one of the cars I've always favored in LFS, but could never quite hold a drift without spinning, all of the sudden I felt the steering and sliding movements in a much more natural way. Just like a real car, the self aligning torque was quick, fast, and during a slide, it was as if the car corrected itself, requiring only just catching the wheel at the right time. Drifting never felt more natural to me than this, and I was able to drift like a pro with very little practice, and do it over, and over, and over again.

Driving The Limit

With the wheel feeding back so much more detail, it's a lot easier to feel where you are around the limit of the tires. There is a very noticeable and wide range of resistance building up and down when you approach and go past the limit. When I would lose control of a slide, I didn't feel surprised, or that the car spun out of nowhere. It was as if I knew it was coming, I had warning, I chose to ignore the warning, I decided to push a little more, and when the rear end went out, I accepted that I had it coming. In some sims it was easier to recover once I got past the limit than in others, but the important point is that as a driver, the wheel gave me enough feedback to know exactly where I was in the scary zone. There wasn't much guessing because the feedback information was so direct. It's as if if I payed enough attention to the car approaching its tire limits, I could massage and balance the car there. This isn't something that anyone would be able to easily do, however the information coming from the wheel is there, and you just have to figure out what to do with it. I wouldn't necessarily agree that the wheel will make anyone faster, but instead will give a driver more information about how to go fast. It will also give more information about when the car has lost grip giving the driver a greater chance to correct. In most cases that alone will improve the driver's success rate and will hopefully result in faster lap times.

Consistency of FFB Delivery

Another impressive feature of this wheel is the consistency at which it delivers forces. Even after extended use or long race sessions. After a full hour of use, the wheel was as responsive and as sharp at delivering feedback as it started. No change, no heat fade, no heat period!! The only thing that faded over time was my strength and stamina trying to endure the intense feedback.

FFB Strength

The specs of the wheel state 13Nm of torque, whatever that means. I say "whatever that means" because this is a complicated topic and the figures aren't quite exact. There is stall, there is peak, and in different situations it varies. What I would tell you for sure is, at its "High" settings, it's more than enough for providing realistic resistance levels on most cars. While at times it may feel like the wheel could be even stronger, especially to really prevent you from going past the bump stops, the intensity of the details delivered can really tire your arms out.

I've never had my arms burn, or had to take my hand off the wheel for my palms to relax ever before. The amount of force produced by the wheel easily convinces you that it has more than enough resistance for any practical use. I can't imagine running full strength in a 20 minute race as only after 2 laps my hand got tired from the vibrations of the feedback. It's not exactly that the force will get you, but the high frequency and sharpness of its delivery. It's like throwing your hands into a paint shaker. Well, see for yourself.

Of course, the intensity settings can be dialed all the way down to nothing. This will depend on personal taste but most likely on your physical abilities.

More Feedback with Sim Commander 4

Since the wheel provides very clear and high resolution feedback from the sims, any shortcomings from the sim feedback is immediately felt. This was the case in all of the sims and games I tried, including iRacing. In iRacing, it wasn't the case that the feedback was inaccurate, but rather there wasn't enough.  Just like a low resolution image viewed on a high resolution display, there was room for more pixels, or rather feedback. 

This need for more detailed force feedback is mitigated by the driver software of the wheel, which is included with the purchase of the wheel. It is SimXperience's Sim Commander software. Customers of other SimXperience products, such as motion systems and SimVibe, will already be familiar with this software package. 

In this latest version 4, it provides support for the AccuForce wheel and exposes a very extensive set of options to tweak and tune. It works by allowing you to select a specific profile for a specific game and overrides or enhances the feedback signals. There are also core feedback settings that are similar to other wheel driver settings, such as default dampening, spring, rotation, and more, which can be adjusted and directly saved to the wheel, and don't require Sim Commander or any profiles to be running in order to take effect while you drive.

Installation of the software is fairly easy as the installer automatically detects most of your current sims and creates default profiles for them.  However, there are so many different options, tweaks, and ways in which you could customize the force feedback, you'd need a degree in engineering. No worries, as SimXperience is working on a detailed guide for how to tune each setting of the wheel. The user interface is a bit busy, and quickly fills your view with tabs, panels, sliders and switches, so it takes a bit of getting used to.  In fairness, SimXperience has admitted that the current functions of the software have far outgrown its design.  They hope to improve its usability in a future version.

After loading the iRacing profile and firing up the sim, the feedback felt as if it was turned up to 11! All of a sudden the sim became much more alive, with far more detail, and far more things to be felt.  The engine RPM effect allowed the feel of the slightest and highest vibration pitches when going up and down the RPM range.  The feedback forces didn't disappear with higher frequencies, they just outputted higher and higher detail frequencies.  

Being able to feel the road surface seams, curb patterns, down shifts, wheel hopping, and engine vibrations made the sim feel much more alive and immersive that ever before. At one point I was sure I was able to feel the car drive differently as fuel load decreased.  As if the forces got subtly sharper from the car being lighter. This was force feedback on a whole 'nother level. Driving without the Sim Commander effects just made the sims feel dead. 

Some of the "effect" options exposed by Sim Commander are not really effects.  Sim Commander features a plugin specific to the game you're playing which pulls out real time physics data updated at a very high frequency and produces feedback on top of it.  In other words, the feedback is based on the physics of the sim! The question then becomes, why didn't the sim output that feedback information in the first place? Perhaps because of current hardware limitations, game developers don't see a need to go any more detailed. Hopefully the AccuForce wheel changes that. In the mean time, the Sim Commander enhancements do just fine. 

Other options, however, are simply effects, in that they tune the feel of the wheel, such as the amount of friction, dampening, and filtering.  Each effect option is customized separately and can be toggled on and off.  The list is extensive, so when Sim Commander comes with its tuning guide, it will be a must to understand if you want to get the most out of the wheel.

Standard vs. SimCommander FFB

The difference in force feedback when using Sim Commander is easy to see. Well, easier with the help of some masking tape.



The integration with Sim Commander really makes this wheel stand out in a unique way. While there are a number of other direct drive wheels on the market, none of them come with a package that actually enhances the feedback information fed to the wheel by tapping directly into the game's API. 

The great thing is, is that Sim Commander already includes profiles for almost all popular racing sims. SimXperience also claims that with Sim Commander you can create force feedback for games that don't even output any!! It's like adding more pixels to a low resolution image so that the high resolution display you're viewing it with can live up to its potential.

I am sure it's possible to have even higher quality and even more precise hardware than what the AccuForce wheel offers, but it would be a bit pointless if there wasn't a way to get more information from the sim. The AccuForce wheel already senses and feeds back beyond what the sim reports, so the Sim Commader is necessary just to fulfill the capabilities of the wheel.

Overall, the default force feedback was very impressive, especially with the tuning aspects.

Stats For Nerds

Using the WheelCheck tool, developed by iRacing staffer David Tucker, the measured linearity of the AccuForce wheel is impressive.  It appears that linear motion starts to take place at less than 2% of applied DirectX force.  In actuality, the plot does record incremental movement below that mark with initial values of:

force | 0  50  100  150  200  250  300... deltaX  | 0 1 4 7 10 49 84...

This certainly explained why the wheel felt far more detailed than any other wheel I had tried before. When I configured iRacing to apply 2% min force, the wheel produced some chattering at the center. Since the AccuForce actually reported incremental values below that mark I didn't think applying min force was necessary and avoided the unnecessary feedback noise. What is even more impressive that is visible in the plot, is the overall consistency of the linearity.  This means that the wheel, when given a particular force will produce results with incredible precision.

At the halfway mark the slope of the chart changes, but only because of the rotational speed limit imposed by the wheel's driver.  It is still evident that linearity maintains after that mark as the slope of the line continues to be constant.  A speed limit on this wheel is necessary for safety reasons, and certainly any force feedback effects delivered to produce such results are so extreme, they are impractical. 

For example, if you crashed into a wall, and the steering rack forced the wheel to rotate with incredible speed in one direction, unlike in a real car, the speed limit of the wheel would make sure you still had your hands and fingers in tact. In a simulator, where the focus is to simulate applicable car behavior, and not crash physics, this is very much a welcomed feature.

When comparing the AccuForce wheel to other wheels on the market, the quicker response time and much more precise and consistent linearity is evident. While this is quite the unfair comparison, as the other wheels are not direct drive wheels, I'm only using this chart to gain perspective on where the AccuForce stands in terms of its accuracy and precision. 

If you have data on other direct drive wheels, please contact me for a fair comparison.

*Data for other wheels supplied by Dmitry Skulkin

The step test, which induces full force in one direction on the wheel, followed by full force in the other direction after 300ms, doesn't quite paint an accurate picture of the AccuForce.  Instead, it only highlights the speed limit, dampening, and oscillation controls built into the wheel.  This certainly doesn't mean that the wheel isn't fast enough to react to changes in force feedback. In fact, SimXpererience has assured me that while it's certainly possible to produce a chart where the wheel would change direction much closer to the change in force time points, it wouldn't feel or drive like a real steering wheel.

What is still evident in the step test chart is the quick initial response from the wheel, which is better highlighted in the linearity charts. In other words, the below chart is a bit useless for highlighting any performance features of the wheel, but rather highlights the safety features very well instead.

Unfortunately I was not able to collect data from other wheels for this test. If you would like to contribute, please contact me.


With price tags ranging from $1,360 up to $1,949, depending on the exact trim and whether or not the Sim Commander software is included, the wheel is very good value, even at its most expensive configuration.

The direct drive system reports force feedback from sims on an entirely new level, and above and beyond from how wheels with reduction systems that use gears or belts do.  It is also significantly cheaper than competing direct drive wheels from other vendors.  Since the performance of this wheel already exceeds the current capabilities of many sims and games to report force feedback, any additional improvements on hardware should return marginal results.  While it's possible to build your own direct drive system by sourcing your own industrial strength motor, controller, and open source software, the cost of the components alone is not much less.

SimXperience has been developing this wheel for couple of years now and they've been in the business of haptic feedback devices for even more.  Paired with the Sim Commander software, which already has plugins for many of the well known games and sims to produce additional feedback effects based on their physics, the potential of the AccuForce wheel is virtually unlimited.  Especially when it's designed, built, and tuned by the people who brought you SimVibe.

On top of the great performance and potential with the Sim Commander software, the wheel is also extensively moddable.  It allows for a variety of ways to plug in external devices, attach custom wheels, and even install custom buttons!

The SimXperience AccuForce is available in three trims. Starting from the lowest price, each progressively priced trim includes the following extras:

AccuForce DIY - $1449 ($1360 for SimVibe owners) - Motor, Controller and Cables DIY Kit. 
+ Base Motor with 2000 Updates/sec via Dual 1000Hz streams (SimXperience Dual-Stream)
+ Encoder resolution with 16,000 PPR (Pulses Per Revolution)
+ SimXperience AccuForce controller box
+ Dashboard software (usable on phones and PC monitors)
+ In game Heads Up display dashboard software

AccuForce Pro - $1749 ($1660 for SimVibe owners) 
+ SimXperience steering wheel
+ SimXperience quick release system with gold contacts (suitable for real cars)
+ Includes adjustable wheel button box with  Carbon Fiber / Aluminum paddle shifters
+ Accommodates a wide variety of real world racing steering wheels
+ Desktop Mount Available but rig mounting is highly suggested
AccuForce Pro MOMO Edition - $1949 ($1860 for SimVibe owners)
+ Choice of three MOMO steering wheel options instead of the SimXperience steering wheel

Detailed specs and ordering information can be found at www.simxperience.com.

Where you'll find the sense and funds to buy this wheel, is entirely up to you.

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