Meet the Obsys, BOS Suspension's new inverted downhill fork. Boasting a whopping 220mm of travel, the fork is air sprung, with a design that was heavily inspired by BOS's work in the motocross world. Why go with an upside down design? According to Olivier Bossard, the company's owner, they found that the fork felt more composed under heavy braking, with a precise and accurate feel that they weren't able to achieve with a more typical design.
BOS Obsys Details
• 220mm travel
• Air sprung
• 42mm stanchions
• Wheel size: 27.5" or 29"
• Externally adjustable rebound, low-speed compression, air preload
• Boost 20 x 110mm spacing
• Weight: 3180 grams (claimed)
• Price: TBD
Two valves protrude from the top left side of the fork, where the air spring resides. One valve is to adjust the base air pressure, and the other to adjust the air preload, similar to what would you'd find on a coil sprung fork. The preload feature allows riders to dial in their ride height by adjusting the amount of effort it takes for the fork to begin going through its travel.
The Obsys' right stanchion houses a closed cartridge system, with similar architecture to what's found in BOS' Idylle RaRe fork, including the Frequency Control Valve (FCV), an inertia valve that relies on a weight perched atop a spring to control the flow of oil through the damping cartridge. The spring-loaded weight remains in place when a rider pushes down on the handlebars, but when the wheel encounters a bump it moves downwards, which lets the oil flow freely, allowing the fork to soak up bigger hits.
Low-speed compression is adjusted by finding a flathead screwdriver and turning the screw found on the damper side top cap. A hydraulic bump stop makes it virtually impossible to completely bottom out the fork – no matter how big you go, there shouldn't be any need to brace for the a harsh impact upon landing.
Traditionally, upside down (USD) forks haven't been as stiff as 'regular' forks, partially due to the lack of a brace between each side, but BOS has taken steps to ensure that the Obsys is stiff enough for the roughest DH tracks. Those steps include going with 42mm stanchions, increasing the clamping area of the crowns, and ensuring that there's plenty of bushing overlap as the fork goes through its travel. The fork will work with either 27.5” or 29” wheels, with two different steerer options available to adjust the offset. One steerer has the standard offset, while the other allows it to be set at +3 or -3mm.
How much will the Obsys cost? That number is still up in the air, but when it's determined sometime in the next few week, one thing's for sure – it won't be cheap.
Along with the Obsys, BOS have a new coil sprung shock on the way, one that's aimed at both enduro and DH riders. The Syors has a completely new piston design, one that was derived from BOS' work in motocross and rally racing. There's a hydraulic rebound bump stop that prevents the shock from bucking when it gets deeper into its travel, along with a 'Kick Valve,' which BOS says helps minimize the harshness that comes from high speed, square edged hits.
The Syors will be available in November in a range of sizes, including metric and trunion mounted options. There will also be the option to install a compression lever to firm up the shock for pedaling. Like the Obsys, the price of the Syors is still yet to be determined.