SRAM has published a patent application
for an electronic and wireless suspension controller, which could be used with sensors to automatically adjust the compression damping of the rear shock. The patent was filed in December 2019 and published in June this year.
Of course this is not the first system to promise seamless and automatic adjustment of a bike's suspension.Fox Live valve
has been around since 2018, and RockShox, along with Lapierre and Ghost, showed off their e.i system as early as 2012
, but that's no longer available. So what makes this different?
Both Live Valve and e.i offer noticeable benefits, but downsides too. Neither caught on in a big way.It's Wireless
Both Fox Live Valve and e.i use wires to connect the various sensors (accelerometers and, in the case of e.i, a pedaling sensor) to the shock via a separate frame mounted battery/controller. This meant that, in both cases, it wasn't compatible with many frames. SRAM's new system appears to be a self-contained unit (battery and all) that sits on top of the shock. That means it should be possible to mount it to almost any frame.
It looks like the electronic controller won't work with existing shocks, as the architecture of the head valve (at the top of the piggyback) is quite different, but the controller is removable and replaceable. I'd be interested to see if it's possible to replace the electronic controller with a manual adjuster, in case of failure or a flat battery, or to allow one shock design to work with the electronic actuator or a manual dial. It Has at Least Three Settings
Instead of using a solenoid to toggle the compression circuits in the shock and fork between fully open and fully closed like Fox's Live Valve, SRAM's system uses a rotating electric motor and a system of gears to turn a threaded plunger, which then moves into or out of the shock's head valve. The patent art depicts three settings for the plunger. Open, where oil is allowed to flow past the plunger and through a port below; partially closed, where the plunger closes off the port but allows oil to flow through the parallel high-speed shims, and closed, where oil can't flow through either of these paths and is forced to go through the lockout shims above. How oil flow is regulated is nothing unusual. It's how the shock/controller changes between the three modes that's different.
I say "at least three" modes because it might
be possible to minutely adjust the position of the plunger in the open mode, without fully closing the port, in order to fine-tune the low-speed damping in a sliding-scale sort of way. The patent document doesn't go into this, so this is pure speculation, but that could
allow the shock to be fine-tuned to the terrain at hand while descending, either by automatic sensors and an algorithm, or by a bar-mounted controller. You could imagine, for example, the system automatically firming up the compression just a few clicks on a smooth flow trail, or if it detects you've been in the air a long time suggesting a big landing is imminent.
However, there are a couple of reasons to doubt this "sliding scale" theory. Most importantly, the patent doesn't explicitly talk about a graduated scale, and the power requirements to regularly adjust the valve position might be too much for a small battery if you want to have a reasonable battery life. So while the sliding scale adjustability might be possible with this screw-in plunger, I think it's more likely that the system is intended to switch between three distinct compression settings. It May Use Both Rider & Terrain Input to Determine Settings
The document is fairly detailed on the system's output (how it can control the compression damping) but it's less clear on what the system's inputs would be.
It does mention a handlebar-mounted remote that could manually control the shock. Anyone who's ridden - or indeed looked at - a Scott TwinLoc bike will appreciate the benefit of a wireless lockout system over current offerings, but this isn't exactly groundbreaking. The patent refers to automatic adjustment of the suspension, but remains vague: "the bicycle may have one or more sensors to measure and/or detect various parameters ... e.g. speed of the bicycle, a pitch angle of the bicycle, a crank assembly torque, etc."
So while Fox's Live Valve takes input from accelerometers in the fork, swingarm and frame, opening the shocks if vibrations are detected, it looks likely SRAM's system will be using speed, pitch and pedaling sensors as inputs which feed into an algorithm to decide what to do with the damper. There may be other inputs, perhaps including an accelerometer on the fork which can detect bumps and open up the shock before said bump reaches the rear wheel. After all, this is how the e.i. system worked.
The patent doesn't refer to a controller for the fork, but a wireless symbol is seen on the top of the fork in one image, so this could suggest an input sensor/transmitter on the fork (e.g. an accelerometer) which might communicate with the shock controller. The same drawing shows two wireless symbols on the stem, which could be a central computer and/or a manual remote switch.
The phrase "crank assembly torque" is particularly interesting. E.i. used a simple magnetic cadence sensor in the bottom bracket to detect when the rider was pedaling and opened the compression damping whenever pedaling stopped. A torque sensor might do the same job but with a faster reaction time, making it harder to catch the system out.
I also found this patent
for a crank sensor, which also was filed by SRAM in 2019 and published in 2021. It's not a torque sensor, but it is claimed to fit inside a crank axle and "measure angular velocity or position [of the crank] in less than a single revolution of the crank axle" In other words, it would detect pedaling faster than a magnet in the BB, which only detects pedaling once per revolution. Here's the really juicy bit: "The apparatus also may include a wireless transmitter to communicate with another component, such as a suspension controller."
So perhaps this crank sensor is one of many possible inputs for the suspension controller. It may work like an updated version of e.i., with faster pedal detection, three (or possibly more) compression modes, and no wires. It could be that SRAM are aiming towards a complete wireless ecosystem, building on their existing wireless AXS gearing
and dropper post. Perhaps the wireless shock controller could be used with an array of detectors (cadence/torque, speed, accelerometers, bar-mounted remotes etc.), and be configures to respond to multiple different input sensors at once, adjusting the shock to suit the terrain and/or what the rider is doing. Disclaimer
To be clear, I don't know anything about this product other than what I can glean from the patents linked in this article. I don't know if the product will launch tomorrow, or in a year, or never. And of course, much of the speculation I've made about how it might work could be way off.
With that in mind, feel free to have a look through the patent document yourself (I'd recommend a strong coffee first) and let us know how you think it could work in the comments.
: There have been accusations of journalistic impropriety regarding this article from Wheel Based
. Dan at Wheel Based wrote an article about this patent before us, and he feels that we've taken inspiration and information from him without credit. We didn't do that, and I've personally reached out to him to try to get on the same page, and offered to show him some information on how we got our info. We've acted in good faith, but I should apologize for our salty pushback in the comments. I understand how it could seem like we're just ripping off the little guy, but it's really disappointing to see people attack Seb's hard work when that's not the case.
We didn't get onto this patent through the Wheel Based story. We have plenty of sources. I've been aware of and chasing down info on this shock since 2019, and we go looking for new patents on a regular basis. In this instance, digging into whether this dropper post
on Nino's bike is a new RockShox product (before this patent was public), got me some information on this project that lead to this patent. We've been writing patent-based articles since 2018 (likely earlier, but that's the earliest one that comes to mind), and it's a common practice across cycling media. Never mind that, being first doesn't grant exclusivity on a topic; we don't get mad when other media outlets report on a bike we spotted and reported on first, and we're not going to get mad if Wheel Based ever talks about the pedal sensor patent we're the first to assess in this article.
We're always keen to work with people and our policy is always to give credit when our reporting is coming from somewhere else. Whether it's Vital or Bike Mag/Beta or Bicycle Retailer or users here, we're not insecure about credit. We have had communications with Wheel Based in the past, but not for quite a while now. Dan is a smart guy doing interesting stuff, and while I don't agree with some of his assessments, he's been quicker than us to look at several patents. All the power to him—I need to improve our systems to monitor the major players' filings. If we ever come to a story through him or build off of his work, we will absolutely give credit, but he doesn't have exclusivity on assessing public patents.
Several of Dan's comments have been deleted for violating our TOS, but he's welcome to criticize us or give his perspective. I appreciate having his voice on the site, and I'm hoping to have constructive dialogue with him.
And finally, I'm looking at his analysis now, and he has come to some very different conclusions than we did—for example, he didn't mention the pedaling sensor patent, and from my limited understanding he seems to think this is going to be a terrain-reading system while we think it'll be based more on rider input. I believe people who read our respective stories closely can see that they're independent takes on publicly available information.
I hope this helps shed some light on our perspective. Regardless of if you think we're in the right or wrong here, please don't attack Seb Stott for it. He's not a thief, trash, scum or any of the things being said. I'm the one who's responsible for assigning him to analyze that patent and write a story, so if you've got a problem with our approach, blame me. And by all means if you enjoy his work go follow Wheel Based. It's all cool bike stuff, and I'm genuinely excited to see what this technology looks like if and when it comes to market.
Brian Park, Head of Editorial