A video posted from Formula today reveals a piece of mountain bike history that has been hidden for 10 years. While talking about the Formula Nero's 3Air triple-chamber air-spring system, Chris Porter revealed he had made a similar prototype fork for Fabien Barel in 2009.
Barel was running a prototype Mondraker frame in 2009, designed by Cesar Rojo, that would form the basis for the brand's future Forward Geometry.(reducing the stem length and then adding that length to the front centre). In combination with Rojo's Zero Suspension system, Barel took the bike to the win on his return from injury in Maribor and then earned fifth at the World Championships later that year.
Forward Geometry wasn't the only new tech on that frame. Chris Porter created a fork with three air chambers that remained hidden from the world until now. There was a positive chamber, a negative chamber and a third one that controlled end stroke progressivity. This third chamber was not a traditional bottom-out chamber, which operates only at the end of the travel (and often in a sudden, uncontrolled way). Porter's design allowed for fine-tuning the compression curve from about half of the stroke to the end of the fork's travel. Chris claims this allowed them to tune the fork from track to track - a linear rate for flatter tracks to a more progressive rate on steeper tracks, where the rider needed more support. Chris hid the technology by creating a fake extension at the top of the spring-side stanchion tube.
There's a full bike check from that era here, although it doesn't look like the bike has the modified fork installed: