Fox Racing Shox test new electronic suspension

Geoff Kabush and Catharine Pendrel spotted with ‘wired’ forks

What we once thought was perhaps a prototype Shimano XTR Di2 transmission on Geoff Kabush’s (Scott-3Rox Racing) new Scott Scale 29 actually turns out to be some sort of electronic control for his Fox Racing Shox suspension fork that both he and Catharine Pendrel (Luna) are testing. But is it simply a battery-operated remote lockout? We don’t think so. Here’s why.


Visual inspection of race photos from this past weekend’s Mellow Johnny’s Classic shows a small wire leading from the top of the fork damper on Kabush’s bike to some sort of switch on the handlebar. When asked, Fox was tight lipped regarding the new fork.

“Fox is always developing new products through its Racing Application Development (RAD) program,” Mark Jordan, Fox’ global marketing and communications manager told BikeRadar. “Fox strongly believes that racing provides the best environment for testing and all future product developments go through this program in one form or another. With this in mind, there will be times when some products may be seen in the public whether or not we are ready to communicate about them. Right now, there are no new developments that we are ready to communicate.”

The obvious assumption is that Fox are developing some sort of electronically actuated remote lockout lever.

While more complex, in some sense, than a mechanical system, there are still some advantages: shorter lever throw (or in this case, a pushbutton), potentially faster response, weatherproofing, and more flexible switch positioning — all of which are highly enticing to cross-country racers.

Pendrel had her remote mounted to the right side of the bars while Kabush had his on the left
Pendrel had her remote mounted to the right side of the bars while kabush had his on the left:
Dave McElwaine/

Pendrel had her remote mounted to the right side of the bars while Kabush had his on the left

Electronic lockouts aren’t new, however, and though past incarnations were only modestly successful, one common theme was that they didn’t require much power to operate — after all, it’s just a tiny valve that needs to be opened and closed.

Yet Kabush’s bike is fitted with an energy-dense Shimano Di2 battery that’s designed to last 1,600km (1,000 miles) moving far more power-intensive front and rear derailleurs.

Fox and Shimano have collaborated on at least two projects in the past (the current mechanical remote lockout lever and the 15mm thru-axle standard), and while Shimano are often notoriously conservative, Fox have already demonstrated that they’re not afraid to aim for the bleachers in regards to test concepts, so our money is on a more elaborate electronically controlled damping system.

We’re not expecting a system similar to Cannondale’s seemingly defunct Simon setup, though.

Cannondale’s awe-inspiring Simon fork may not have seen the light of day, but the concept was incredibly intriguing — and absolutely impressive. The electronically controlled valve and the multiple damping maps seemed to work as advertised. While Simon’s main developer, Stanley Song, left the company in 2009, he’s continued to work for them on a contract basis so we’re still crossing our fingers that we may actually see the Simon fork in production someday.

Geoff Kabush (Scott-3Rox Racing) competed at the Mellow Johnny's Classic with a prototype electronically-controlled Fox fork. There's a Shimano Di2 battery mounted to the down tube and there's a wire clearly visible coming out of the top of the fork on the damper side
Geoff kabush (scott-3rox racing) competed at the mellow johnny’s classic with a prototype electronically-controlled fox fork. there’s a shimano di2 battery mounted to the down tube and there’s a wire clearly visible coming out of the top of the fork on the damper side:
Dave McElwaine/

Geoff Kabush (Scott-3Rox Racing) competed at the Mellow Johnny’s Classic with a prototype electronically-controlled Fox fork. There’s a Shimano Di2 battery mounted to the down tube and there’s a wire clearly visible coming out of the top of the fork on the damper side

Song explained to BikeRadar that Simon’s constantly variable electronic damper port required an enormous amount of power and the included 2000mAh battery yielded just 2-8 hours of ride time. The Shimano Dura-Ace battery’s capacity is roughly one-quarter that of Simon’s pack, so we’re not expecting a similar system here.

“Simon was originally designed to operate independently of the hydraulic forces in the damper,” Song told BikeRadar after we tracked him down at his new home base in Taiwan. “I grossly overlooked some of the nonlinear flow dynamics, and it turned out the valve actually did need to fight the hydraulic forces. As you can imagine, the system suddenly needed to fight a very big uphill battle. In a sense, it worked, but at the cost of a huge battery and a short operating life.

“As you can see, the battery requirements stem from the mechanical design. And there are many different mechanical designs from multimotor design, to different shaped valves, or even magneto-rheological fluid,” Song continued. “They would all have different battery requirements.”

Fox actually do look to be developing a magnetorheological damper system similar to the Delphi system used in the Chevrolet Corvette and other advanced GM vehicles. Dr. Dave Batterbee — in conjunction with Dr. Neil Sims  — developed just such a system for mountain bikes at the University of Sheffield and he began working for Fox Racing Shox in June 2010. If Batterbee’s system has indeed come to fruition, the result will be absolutely groundbreaking.

Just like on those GM vehicles, Batterbee’s concept incorporates accelerometers to detect impact forces and assuming the system works in a similar fashion, those sensors feed information to a central brain that then adjusts the voltage applied to the damper chamber — thus virtually instantly changing the viscosity of the magnetorheological damping fluid based on real-time demands. How fast, you wonder? GM’s system adjusts itself 1,000 times per second.

In concept, the system we speculate Fox are using would thus deliver nearly the same feature set of Cannondale’s Simon, but with far lower power demands, and at least in theory, more instant changes in damping characteristics. In practice, it is effectively the electronic analogue to Fox’s own Terralogic system or Specialized’s Brain but with no additional moving parts, a much faster response time, and a much wider range of settings instead of just ‘on’ and ‘off’ — in other words, the absolute holy grail of mountain bike suspension.

Looking even further forward, there’s no reason this also couldn’t be applied to rear suspension, too.

This still leaves the question of the remote switch, however, and at this point we can only speculate. It’s possible it’s an on-off switch for the magnetorheological system, a lockout override, or perhaps a variable fluid viscosity adjuster but either way, Fox are clearly not relying on the setup to be a full-time automatic system.

Regardless, something is brewing between Fox and Shimano, and we expect the full reveal just prior to Sea Otter. If our hunch is correct, it’s going to be amazing. Stay tuned.


BikeRadar would like to extend our thanks to reader monsieur_velo for the tip that led us to Dr. Batterbee’s employment history.