Fox “Active Valve” suspension predicts terrain w/ wireless sensors & radar!

fox active valve electronic mountain bike suspension controls shown in patent drawings

I’ve ridden the original Fox Live Valve and it’s amazing. Making a 150-160mm bike climb like an XC bike is more than fun, it’s a game changer.

The downside (other than cost) is it requires wired sensors at the rear dropout and on the fork, plus a dedicated battery/brain unit mounted on the front triangle, all wired to the compression damping circuits on the fork and shock.

The original Fox Live Valve wire and sensor layout.

Now, new patent filings from Fox show that they’re looking at whole new “Active Valve” system with a wide range of updates and improvements:

  • Wireless control
  • Smartphone tuning & integration
  • Wheel, handlebar, saddle, pedal & other sensors
  • Bike-to-bike communication
  • Active compression damping management
  • Predictive RADAR/GPS terrain mapping

There aren’t a lot of pics, but trust me, it’s worth the read. Disclaimer: Any features or specs mentioned in this story are purely my speculation based upon the contents of their public patent filing.

TL;DR – What is Fox Active Valve?

The switch from “Live Valve” to “Active Valve” electronic suspension management upgrades the original Live Valve’s on/off compression damping management to an infinitely adjustable system that can adjust the damping anywhere between fully open and fully closed, giving it complete control over every aspect of the suspension’s performance in real-time.

Add in predictive (radar! lasers!) terrain monitoring and additional on-bike sensors, and it can adjust suspension proactively instead of reactively and include rider inputs into the equation. There is also a suite of new wireless and app controls for tuning its performance.

Live Valve wireless controls & app-based tuning

The original Live Valve system puts the controls on the battery/brain unit, which is typically mounted on the downtube or upside down under the top tube. Neither position makes it easy for mid-ride adjustments, and those adjustments are only changing the initial bump sensitivity tolerance, not switching between unique tunes.

patent drawing for next generation fox live valve active mountain bike suspension
Example user-interface buttons and settings that could be in a Live Valve smartphone app. Click any image to enlarge.

Fox’s current Live Valve app does let you choose between Open, Comfort, Sport, Firm & Climb modes, but you have to stop, open the app, and select the mode.

The patent suggests adding a wireless controller, which could be bar-mounted, much like a dropper lever, and give the rider on-the-fly adjustments of the threshold bump sensitivity, but as best I can tell you’ll still have to use the app to change tunes.

At least these patent drawings look like they’re about to give you more control over the system’s sensitivity and create your own unique tunes.

patent drawing showing OEM tuning controls for 2nd gen fox live valve active mountain bike suspension

The chart above shows the various controls available for each mode. Thus far, these settings have only been adjustable by Fox and their OEM partners, and for good reason…you can imagine how easily it would be to FUBAR the settings and ruin your bike’s performance.

patent drawing showing smartphone app tuning controls for 2nd gen fox live valve active mountain bike suspension

It’s likely a consumer-facing version of this would be simplified (and hopefully have a “restore to factory settings” button) more like the version above, and with a nice UI on the app.

patent drawing for next generation fox live valve active mountain bike suspension
All patent drawings from Fox’s patent application. This one shows the sensors and features of the smartphone that could be used to make a connected app function.

The filing suggests Fox Live Active Valve may pull data from your phone’s sensors to adjust suspension, too, however I think a more practical (as if any of this is practical) use of this is geotagging terrain using a smartphone’s GPS so to crowd-sourced data to create trail-specific tunes.

This could easily be a “pro” (paid) subscription feature from Fox or bundled into revenue-sharing agreement with apps like Trailforks or MTB Project.

Wireless Live Valve sensors in wheels, handlebar, pedals & more

fox active valve electronic MTB suspension monitoring could use sensors in the wheels, cockpit and dropper seatpost

Why stop with sensors at the fork and rear axle? The patent considers sensors inside the rims, handlebars, and seatpost, for a more holistic view of the impacts reaching the rider.

Conveniently, Fox owns Race Face, and Race Face makes all of these parts.

A dropper post sensor makes a lot of sense, telling the suspension to open up when the saddle’s dropped since, presumably, it means the rider is descending.

Live Valve already knows if the bike is pointed up or down a mountain, leaning, or turning, but more data points could give it better information to work with.

The big functional improvement Rockshox’s Flight Attendant system added over Live Valve is a crank-based cadence sensor. It can tell how much and how quickly you’re pedaling, adjusting the suspension accordingly to maximize efficiency.

Now, Fox appears to be considering crank and/or pedal-based sensors, likely to accomplish the same thing. Adding a strain gauge to the system could let them know how hard you’re pedaling, too, to optimizing for sprints versus cruising. (Race Face had a spindle-based power meter that does this)

Add a wheel speed sensor and it’ll know how fast you’re traveling, too. Raging DH descent? Curving flow trail? Grinding climb? It could adjust accordingly, no matter what and how you’re riding.

Lastly, speed sensors inside the suspension could tell how quickly the fork or shock is compressing, and adjust damping accordingly.

Theoretically, this could allow them to give the suspension different characteristics at any point in its travel.

Forget tuning with volume spacers and air pressure and leverage ratios, just let the computer keep it soft at the beginning and firm up at the end while still allowing full travel.

In total, Fox mentions sensors for the following:

  • Terrain
  • Environment
  • Temperature (ambient and component)
  • Speed
  • Pitch
  • Roll
  • Yaw
  • Component activity
  • Tire pressure
  • RPM
  • Chain tension

…and that such sensors may be embedded, moved, mounted, or otherwise positioned to allow any desirable range of adjustment.

Multi-vehicle communication

multi-bike sensor sharing on wireless fox live valve design, shown in patent drawing

Fox also mentions that the wireless capability could be used to send terrain and suspension data from a lead vehicle to a follow vehicle, presumable making the second (and third and fourth…) bikes in a train able to handle the terrain even better than the first.

But…it also mentions that a second vehicle (think, team car) could transmit data to the first vehicle. I’m thinking recon drones…🤯

Predictive terrain sensing with Radar, LiDar, ultrasound, lasers…

The wildest part of the patent involves pointing a sensor (could be infrared, radar, 2D or 3D imager, ultrasonic, photoelectric, LiDar or similar – it specifically mentions the STMicroelectronics VL53L0X) at the ground in front of the bike to detect terrain changes.

This could detect upcoming obstacles, bumps, or holes, and also detect their shape and abruptness. Imagine a suspension that adjusted for every stone in a rock garden, smoothing the terrain as you crank through it.

It even mentions systems so sensitive as to apply to road and gravel bikes, too.

And it talks about changing rebound speed, too, where the current system only controls compression damping. Supposing it detected a pothole, it could speed up rebound damping so the wheel quickly pushes down into it and minimizes the drop, while compression damping is opened up to absorb both entry and exit impacts.

(Side note: Bose made a similar system for Lexus, and it worked magically, but it was too expensive to hit mainstream, however it could also pull the wheels upward rather than simply let an obstacle push them up. It required electromagnetic motors, which were too heavy for cars, so it’s unlikely we’d see that level of suspension reach bicycles. Recently ClearMotion acquired Bose’s tech and is working on a more commercially viable version..so, maybe for eMTBs someday?)

Fox Active Valve electronic suspension control

fox active valve replaces live valve with a variable compression damping system

If all that sounds crazy, the most interesting new aspect of the patent filing is Active Valve, a new electronically controlled damper that actively controls the compression damping by adjusting damping fluid flow in real time.

Here’s how it works:

  1. During compression, damping fluid flows into the Active Valve compression circuit (450) thru the inlet port (402). The fluid exits through another port (403) and would presumably return thru a separate rebound circuit.
  2. A spring-loaded needle (412) covers the inlet and is held in position with a spring (415), so any compression must overcome the spring’s (415) force to push it back and open the compression circuit.
  3. The strength of the spring would be the “base tune” for the compression circuit, and its preload is user adjustable with a knob attached to a screw (408), even allowing it to partially or fully open a flow path between the entry (402) and exit (403) ports.
  4. The spring (415) rests against a piston (405), and behind that piston (405) is the Active Valve reservoir (407).
  5. Feeding the reservoir (407) are three cylinders (451, 452, 453) filled with damper fluid.
  6. Each cylinder has a piston (465) and rod (466) that can be moved by a solenoid (475) to push fluid into the cavity (407) behind the spring’s backing piston (405).
  7. More fluid behind the piston (405) adds more preload to the spring, making it harder to push the needle (412) back and open the compression circuit.
  8. The Solenoids (475) can also retract each cylinder’s pistons (465), pulling fluid out and reducing preload pressure on the spring, thus making it easier for the shock to compress.

The appearance of three cylinders is likely to give Fox the ability to claim “one or more” active valves may be used so as not to limit the scope of the patent. They also state that multiple active valves may be used to control various things like shaft speed, rebound circuits, and more.

What’s the difference between Fox “Live Valve” and “Active Valve”?

Live Valve uses a simple latching solenoid, basically an open/close port that uses a small electromagnet to open or close a compression fluid port in a few milliseconds (the sensors monitor the terrain 1000x per second).

Live Valve is On (Firm) or Off (Open), relying on the mechanically adjusted settings for either position to manage compression damping.

Active Valve, as described here, is far more complex, using an electronically controlled hydraulic system to infinitely adjust compression damping force in real-time.

This gives it much more granular control, ranging from wide open to fully closed and anywhere in between, adjusting in milliseconds based on input from all the sensors.

This, combined with cadence and other sensors, would make it a much more “active” system than Flight Attendant, which simply switches between preset modes (eg. open, trail, closed).

closeup details of new 2023 scott genius trail bike with adjustable travel
Closeup details of the Scott Genius, which can adjust between 0-100-150mm rear travel.

I could imagine Fox also using an Active Valve system to adjust travel. They’re already doing this mechanically on the Scott Genius trail bikes, but an Active Valve system could easily decrease travel automatically on the climbs and increase it on the descents. I bet this is coming.

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When does Fox Active Valve launch?

The patent was filed in 2021 and is still pending. There is no public release date, and no public acknowledgement they’re even working on this. But… the original Live Valve launched in August 2018, so it’s almost five years old, about time for an update.

And, Pivot Cycles recently offered a free Live Valve upgrade on select mountain bikes, which (to me) suggests they want to move inventory before the next generation arrives.

Fox does not comment on future products, and any and all features, benefits, and functionality described herein are purely my speculation.

What does it mean for riders? For racers? For cars?

It’s worth noting that every motorsport bans “active” suspension management in competition.

Fox has OEM Live Valve placements on the Ford Raptor and Polaris UTVs, among others, but those are “recreational” vehicles (that just happen to have game-changing performance thanks to the active suspension control).

Mountain biking is the only sport where it’s (currently) allowed, and both Fox and Rockshox (and maybe SR Suntour) have products available to their top racers, with (most of) those systems also available commercially for recreational riders.

So, yeah, it’s a ton of tech in a sport with simple mechanical roots, but it’s exciting to see what’s capable when governing bodies don’t get in the way. Look away, UCI, look away…

To be honest, even though the drawings show a mountain bike, nothing about this patent limits it to bicycles. I could see a lot of these concepts being applied to cars, trucks, snowmobiles, motorcycles, and UTVs, too.

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