Methods and Apparatus for Suspension Adjustment by Fox

In this article, we’ll be discussing a Methods and Apparatus for Suspension Adjustment by Fox, US publication 20200309229. The publication date is Oct 1st, 2020 and the filing date is June 16th, 2020.

This article will be discussing Fox Factory’s Live Valve. I know this isn’t a new idea but the USPTO has released patent documents that define what the Live Valve system actually does and what it could do in the future. I’d like to share some lines that Fox have presented to the USPTO, without any marketing jargon. This article will show explicit details on the mechanisms and the actions of Live Valve, including possible future developments. There’s a lot of information out there that Fox tell the public, but I’m going to tell you what Fox told the USPTO. I also think there are some philosophical items that should be considered about this type of technology.

This patent is a continuation of numerous patents dating all the way back to 2009, which tells us that Fox may have been working on this for more than a decade now. Additionally, there are numerous other patents that relate to mechanisms in Live Valve, such as adjusting a fork.

Brief Summary (tl;dr)

This article describes the Live Valve system as Fox want it protected. There are also some additional features that may not be implemented in the current system. The Live Valve system works by sensing multiple inputs such as terrain, pitch, etc., sending the sensed data to a computer that contains specific algorithms that determine a voltage level to send to the damper circuit valve in the shocks. The voltage level output to the shocks corresponds to a level of fluid flow that is predetermined by the algorithms. So, as the rider rides over bumps or climbs, the damper circuit is automatically adjusted for an optimized ride, with absolutely no input from the rider other than picking the algorithm they want to run.


An active system receives an input and then changes the way a component reacts to the input. An active system many of us deal with regularly is an All Wheel Drive (AWD) system in a car. The AWD system contains wheel speed sensors and automatically adjusts power between the wheels during a slip scenario, for optimized grip, by locking differentials (Torsen) or activating clutch packs (Haldex), among other methods.

Alternatively, a passive system is a system that does not react to an input situation. A passive system that many others deal with regularly is a 4×4 system used in trucks. These systems have open differentials, no sensors, and locking of differentials is a manual operation performed by the driver. There are advantages and disadvantages to both systems, but I won’t discuss them here. There’s a ton of articles across the internet for that.

In an example scenario, let’s think about a non-aero car. When you hit the brakes, forward momentum will cause the car to dive forward, called pitching forward. When this happens, weight is transferred away from the rear tires and toward the front tires. This can cause a ‘loose’ scenario when turning if you’re turning and braking at the same time, so you’re more likely to lose the back end of the car and spin out of control. This is a passive system, where the car does not react to an input scenario.

Now, let’s introduce a scenario where the car has a hypothetical active anti-dive system. There are sensors inside the suspension system, brake pedal, steering wheel, etc., that sense inputs. There are also servos, motors, etc., to adjust valves, compression ratios, etc., inside the suspension system. When a driver hits the brakes, the car will know the speed and position of the brake pedal, the speed of the car, and various other inputs that will affect the pitch of the car. This hypothetical anti-dive system will receive the inputs from the sensors, send the received inputs to a computer that then calculate an optimized anti-dive output. The computer then tells the suspension motors, servos, or valves what to do. So, the computer should tell the front dampers to close the compression circuits as much as possible to keep the nose in place. The computer will also tell the rear dampers to close the rebound circuit as much as possible to keep the tail in place. The end result would be a much flatter car, and weight transfer is minimized, and grip is preserved. All of this is performed without manual input from the driver. This is just an example scenario and these actions can be performed using other methods such as mag-fluid, air pressure adjustments, or linear actuators that actually move the car.


Live Valve is now a few years old, but probably still near its initial iteration. It’s an active system, responding to inputs such as pitch, terrain, and speed, among other inputs. The entire goal of Live Valve is to create more grip and provide a more efficient pedaling platform. The system optimizes grip to a level you and I cannot attain with a traditional bike, and pedaling is optimized to minimize wasted energy that a traditional lockout cannot achieve.

Live Valve is not exclusive to mountain bikes. Honda are using it in their SXS vehicles, and the Ford Raptor has a similar system. Currently, you cannot go to your local shop and have them install Live Valve. It appears as though Giant and Pivot are the only manufacturers that offer the system to the public.

Thanks to some input from Ryan Rasmussen, I can add that Lapierre and Rockshox had a similar system a few years ago. This system uses one sensor in the fork, and no sensor in the rear triangle, so the fork accelerometer adjusts both fork and shock. A speed sensor was used to determine the delay in the rear shock adjustment. There was also a cadence sensor to sense pedaling and lock the shocks. This system is a bit more crude than Live Valve, but it was a good intermediate step to get where we are now.

I also found a fork system that Magura introduced in 2013. Levy did a great article on how it works.

With the introduction of Live Valve, mountain biking is currently at the equivalent of about 1987 in the Formula 1 time-table, where the technology started its accent to so out of control that the FIA went ahead and banned active suspension systems altogether in 1994. They did this for two reasons, cost and safety. The cars were getting outrageously expensive, insanely fast, and if something went bad in the system, the cars could crash.

Intended novelty

This particular patent appears to try to protect the initial set up using Live Valve, but there’s a lot more information in the document than just the initial set up.

I think if I had to pick a technical novelty here, I’d say the Fox’s system utilizes two data rates; a high data rate (wired) and a low data rate (wireless). The wired data rate is used for the bike itself, where there is communication between sensors and the controller. The wireless communication is between the bike and a phone or computer to export data. So, the whole system communicates via both wired and wireless connections.

In reality, the introduction of very usable and pseudo-mass produced front and rear active suspension system in a bicycle is the earth-shattering novelty here. Making this commercially available is huge. The two data rates are ancillary as far as I’m concerned and is probably in this patent to overcome automotive/moto systems.


I like how this patent starts. The beginning states enthusiastically:

Despite efforts to educate product managers, retailers, and end consumers on the importance of proper initial vehicle suspension set up, it is evident at event support and trail side encounters that many mountain bikes and motor cycles are ridden with improper suspension initial settings.

I rarely see this kind of candid speech in a patent document. It’s refreshing to see Fox basically saying: “People… we’re tired of you fucking up our shit, so now we’re going to make it so you can’t fuck up our shit”. In part, Fox are doing this because they don’t want people, including those that should know what they’re doing, setting up their suspension incorrectly. Fox also state that they want to control rebound and compression settings to prevent packing and bucking.

But reading between the lines, Fox wants an extremely high-performing bike. There’s no arguing the advantages of an active suspension system, if it’s implemented correctly.


Please note that some or all of the items I’m going to quote from the patent may or may not already be implemented into the current Live Valve. This system is complex and I’ll try to pick out key features.

The process is fairly simple from a high-level view. The Live Valve system takes input from a few sensors (terrain, pitch, etc), processes the inputs in a computer (algo-magic), and sends an output to the suspension based on how the engineers have determined the bike should respond for improved performance (damper adjustments).

First, Fox state what metrics the sensors may actually sense; either right now in the current system or in future systems:

In one embodiment, a sensor may be coupled to the rear suspension, such as [a] shock absorber and/or damper assembly, for measuring the operational characteristics of the rear suspension. In one embodiment, a sensor may be coupled to the front suspension, such as front forks, for measuring the operational characteristics of the front suspension. The operational characteristics may include at least one of position, velocity, acceleration, stroke, sag, compression, rebound, pressure, and temperature of the vehicle suspension. 

The sensor data is sent to a processor and parsed based on a predetermined algorithm. The algorithms are the 5 or so settings the rider can choose on a phone/controller. So, each setting will have a different effect on how the shocks respond to the terrain.

The… bicycle is equipped with the processor, such as a suspension setup microcomputer device comprising [a] memory, [a] program having an algorithm and computer for executing the program, which captures data in the memory from the sensors that are coupled to one or more [bike] suspension components (such as a fork and rear shock on a bicycle or motorcycle).

The data may include suspension component relative position data (e.g., inches of compression or full extension or full compression or any suitable combination of such data) and/or other operational characteristics/features of the vehicle that are measured by the sensors.

The algorithm then determines a specific voltage signal to be sent to the shock. The voltage signal corresponds to how open or closed the damper circuit valve assembly should be. Remember, these signals can happen nearly instantaneously as the bike traverses over terrain.

The processor or controller compares the output voltage of [the] sensor to a preset… value and if that value is exceeded, the controller routes a predetermined amount of power from the power source to the valve assembly 511.

In short, the process is: sensor senses -> signal sent to controller -> controller does algo-magic -> controller sends voltage signal to the damper valve -> damper valve opens and closes as instructed.

Fox also state the system can lock and unlock itself automatically based on the input from the sensors for smooth or rough terrain:

Such “lock out” may be… provided automatically in response to some predetermined and sensed vehicle operation condition (e.g., smooth terrain). Alternatively, a “lock out” condition may be the default mode for the suspension whereby the suspension becomes active only upon some predetermined and sensed vehicle operation condition (e.g., rough terrain) wherein a sensor senses the condition and opens the “lock out” so that the suspension may operate for a prescribed period of time or terrain input.

…[the] remote lock/unlock [is] entirely automatically controlled by a controller in response to the input from the sensors and/or when the bicycle is in use. Optionally, the user may be able to override and/or adjust this automatic control using a device.

The system can also sense pedaling based on consistent frequency from a pedal force sensor and eliminate the pedal bob:

…if input from sensor is consistent in frequency with input from a pedal force sensor, the controller may direct a closure of the valve assembly until such synchronization is eliminated or reduced.

In conjunction with this process, a GPS system may also be implemented into the system. So, the bike will track you at the same time its pulling information from the bike sensors. The use of GPS in particular is interesting. Fox can collect metadata from specific trails and understand how the population rides that trail. Even more, they may be able to collect data from a region (Colorado, for example) and adjust bikes according to the region they’re being ridden. Colorado is much dryer and slick than, for example, Western NC. I don’t believe these sensors are currently used in Live Valve:

The controller may also have other sensors on board such as a GPS, a compass, an accelerometer, an altimeter, and/or an air temperature sensor.

Fox also state that this data could be viewed in ‘real time’ in front of the rider on your phone. So, as you’re riding, you can actually watch how much you suck at biking.

The controller may calculate data trends of other useful data derivatives for periodic ‘real time’ (effectively real time although not exact) display on the user interface of the communication device.

The system can even provide service intervals, and even take you straight to service videos when the time comes. How will this effect shops? I imagine the people buying Live Valve are not the same people working on their own bikes, though.

…the controller will log ridden hours and will prompt the user to perform certain maintenance operations, and when data is downloaded to the computer system, such as a desktop/laptop machine, a link to the service procedure for the particular recommended service will pop up.

Fox also state some additional possible features such as blow off valve adjustments, trim adjustments, etc.

…an adjustable manual mechanical blow-off; an electronic wirelessly adjustable blow-off; an adjustable “g” threshold to open valve; an adjustable “timer” to dose valve; an adjustable low speed bleed (which could be a separate adjustment, or a trim adjustment of the main on-off valve); a program mode where it automatically alters open and closing parameters based on sensor input (for example sensing a rock garden); auto (Inertia sensing)/On (always lockout)/Off (no lockout) modes; a wheel speed sensor that can also dictate how the fork responded; a travel sensor either for bottom out, or discrete travel points (to aid in proper sag); and a data storage.


First, Fox describe the calculation method. The controller calculates the change in the change in speed of the fork and shock. I believe this is jerk, or jolt. For all you people playing options, this is similar to the Greek called gamma.

…the controller takes a derivative (differentiation) of the acceleration to determine the rate of change of acceleration for forecasting and implementing adjustment of valve assembly (rebound issue is a big deal) or for determining a data rate or density required to adequately represent current suspension behavior (to for example to cull high rate raw data into more manageable yet representative data streams or sets). For example, if a bump is encountered followed immediately by a dip, it may be desirable to have the rebound of the tire into the dip (terrain following for traction advantage) occur very rapidly. If the valve assembly were opened to an intermediate state as determined by the controller, for the bump an immediately following large magnitude reversal of the derivative of the acceleration (as input from the sensor) may indicate that the controller direct the power source to full opening of the valve assembly to allow maximum rebound velocity…

Next, I’m going to describe how the actual fluid is adjusted with the valve assembly. In short, the voltage sent to the shock moves a voice coil linear actuator, and more or less fluid is moved through the damper circuit. Voice coil linear actuators are what allow speakers to make noise.

Figure 2A shows an example rear shock. Nothing matters in this except for the Fig. 2B box.

Fig. 2B is the valve assembly 511 that automatically controls the flow the damper fluid. Fox state:

…The valve assembly 511 is operable in response to electric current [sent from the controller] and is capable of being modulated or throttled for selective full opening, closing and intermediate opening or “throttle” positions.

The important parts in the valve assembly 511 of Fig. 2B are the valve portion 110 (comprising cylinder 112, orifices 114, piston 116, and spring 118) and actuator portion 120 (comprising coil 122, magnet 124, and back iron 126). This is a voice coil linear actuator.

I’m not going to go into super detail on how a voice coil linear actuator works, but a voltage is sent to the coil 122, this happens, and the piston 116 moves. As the piston moves, more or less fluid moves through the damper circuit. Fox have an important line here that supports the idea of different algorithms sending different voltages to the shock:

Different voltage commands may thus correspond to different amounts of force applied to the piston 116

In short, the different voltages should be able to control the speed and intensity of the movement of the piston, therefore controlling how the fluid flows through the damper circuit.

Currently, the Live Valve system functions on the damper side only, but Fox open the possibility for other adjustable components based on the sensor inputs:

…the controller calculates needed changes based on sensor input and facilitates those changes to dampers, air springs, or other suitably adjustable suspension portions.


In the end, a simple active suspension system, such as Live Valve, has a few ingredients: a memory, processor, sensors, little actuators (or something else to adjust damper fluid), and some programs to act on the actuators based on the sensors. Fox make it pretty clear that they have a lot of room to move forward, but have they gotten it right? Active systems are ripe for errors and if they don’t get this 100% correct, they’ll be in the same place as Magura, Lapierre, and everyone else relegated to the history books. They have to make a system that reacts to every person in such a way that no one notices Live Valve exists, and hat’s not an easy feat.

Eventually, I foresee this system being simplified with the use of magnetic damper fluid, called a magnetorheological damper. A mag-damper uses magnetic fluid and an electrical input to change the viscosity of the fluid (rather than controlling fluid flow like the current system), thereby changing the damping characteristics. The major advantage of this system is that the viscosity of the damper fluid can be adjusted nearly instantaneously, which would be significantly faster than opening and closing valves. There would also be less things to break with less valves, motors, servos, etc.

In reality, this type of system is taking control out of your hands. There’s no arguing that fact. You no longer have an infinite amount of adjustments for you to fuck up. Fox will now make sure your suspension is tight and right. This could absolutely be beneficial for some, while others will completely reject the idea as sacrilege.

This then leads to the situation of 3rd party bike tuners. Will this open an entirely new market for custom bikes tuned by algo-nerds? Will this void a warranty? I’d bet that Fox think their system is 100% secure, but there’s definitely someone out there that will be able to open the settings and change them.

Another item to note is the data logging. Don’t think for one second that every single rock, pedal stroke, and tree you hit won’t be logged and sent back to Fox for analysis. Just as auto companies collect auto data, just as Facebook captures user data, Fox will collect your riding data. Again, I wonder if this data can be used against you on a warranty claim? Yikes. However, it may not be all bad. The massive collection of data will probably be used to optimize settings. Hell, it may even optimize settings based on location. The people riding in super-dry Moab are not riding the same features as people riding in the jungle-moist western North Carolina. Maybe Fox will be able to see differences in suspension data based on GPS data and tune accordingly.

I love data. It’s so much fun to see what is going on inside something from a granular level, then try to improve it and I love seeing this level of data acquisition being used. I spent years doing just that in auto racing, but it was limited to testing only. As much as I’d love to see how fast someone could actually go on a mountain bike, these are the kinds of systems that will create huge problems in mountain bike racing. Active suspension systems require incredible amounts of research to optimize every possible scenario based on the massive amount of data that is produced, not to mention the expensive physical components needed. This is directly related to cost. As cost goes up, small players, privateers, etc. are pushed out of the sport. Remember, the highest level of motorsport on earth outright banned active systems in racing 25 years ago. As much as everyone in the mountain biking community wants to compare the current DH, EWS, XCO, etc. to the F1 of biking, the reality is, is current biking disciplines are equal to good ol’ NASCAR of the 60’s to 80’s. Technology has generally been rejected, there are very little electronics, the machines are simple, the focus is on the rider, and most importantly, the bikes are nearly identical to what is on the showroom floor. All of this keeps cost down and the racing tight. Do you want bike racing to be like F1 or NASCAR?

I hope this article shows how the bike industry is just on the cusp of some serious technological changes. The current Live Valve system isn’t anywhere near the potential limitations that have already been proven in the automotive industry. If this is adopted, the bikes we’ll see in 10-20 years will be modern-day space ships. This then presents the question of; will you buy one? Is this type of technology appropriate for a bike? The only way these bikes become commonplace is broad market acceptance. Do you think they’ll be accepted? Should this type of tech be exclusive specific disciplines like E-bike racing? Let me know what you think.

Thanks again for reading my incoherent ramblings.  

5 thoughts

  1. Active systems are great but fox mentioned it in their intro: people don’t know how to do a baseline setup. Integrating a system similar to shockwiz into the design of suspension components would go a long way and be much simpler. Not sure if that’s been covered in other patent on this live valve.

    1. I’d guess they wanted to skip that step altogether. A quick search found nothing in the patent world for something similar to the Shockwiz, but that doesn’t mean they’re not doing something like that. Or I’m not looking at the right stuff. I’ll keep an eye out.

  2. In the automotive world this is considered semi-active suspension since the system can’t add energy to the suspension, only remove (in a very calculated way). Active would be if the spring and damper were replaced with an actuator. Fully active systems can be dangerous since they can make the system unstable. Practically, semi-active systems could never become unstable. I.e if the valve fails in normally open position you’ll just have a shock with barely damping and if it fails normally closed you’ll have a semi rigid bike. If your active actuator decides to spontaneously extend you could be forcefully ejected from your bike

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