Rumors had been swirling for the last year or so about the future of BOS Suspension's mountain bike division due to the prolonged period of radio silence from the French company. Were they scrapping the bike side of things to focus solely on their rally car and motorcycle suspension? There was no shortage of speculation, but according to Olivier Bossard, the company's owner, he never considered disbanding the mountain bike side; instead, he says that the pullback was done in order to allow them to regain focus and decide exactly what path they wanted to take.
BOS Deville 35 Details
• 160mm travel • Air sprung • 35mm stanchions • Boost spacing • Wheel size: 27.5" • Externally adjustable rebound, low- and high-speed compression • Adjustable negative spring volume • Price: TBD • Weight: TBD www.facebook.com/BOSsuspension/ That path still involves manufacturing high-end suspension, and the new Deville 35 serves as BOS' announcement that they're back in the mountain bike world. The Deville 35 is aimed at the all-mountain / enduro crowd, with 35mm stanchions and 160mm of travel, but it's the fork's internal workings that sets it apart from its competitors.
A 27.5” version is expected to be available in May, with a 29” model scheduled to debut by the end of the year. Final pricing will be determined within the next week or so, but it's expected to be in line with other new forks hitting the market.
Low and high-speed compression can be adjusted externally, and there's also a lever to quickly increase the compression damping.
A look at the damper assembly.
The Deville uses a mono-tube damper; rather than relying on an expanding bladder design similar to what RockShox and Fox use, BOS went with a coil sprung internal floating piston, citing that design's reliability and ability to withstand temperature changes without altering the feel of the fork.
The Deville's high and low-speed compression adjusters are now located on the top, rather than the underside, of the right leg, a welcome change from the previous version. There's also a lever that can be used to control the flow of oil through the compression needle, providing a firmer platform for climbing or smoother sections of trail.
The Frequency Control Valve is designed to quickly open when a bump is encountered from below.
BOS' Frequency Control Valve (FCV) is 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. Keep in mind that in the closed position it's still easy to move the fork through its travel – this isn't an inertia valve that fully locks out the fork, and while the difference between the open and closed positions is noticeable, it's not overly drastic.
Strategic cutouts in the crown and the arch are designed to shave weight without sacrificing strength.
The Boost thru-axle is secured with a pinch bolt.
Rather than using spacers or oil to alter the volume of the positive air spring, BOS figured out a clever way to easily change the volume of the of the negative air spring. Once the air is let out of the fork, unthreading a bolt on the bottom of the fork allows the rod-shaped spacer to be removed, and then replaced with a different size (at the moment there are three options). Rather than changing the fork's bottom out resistance, swapping spacers changes the feel of the beginning part of the fork's travel. This makes it possible to choose between having an extra-soft beginning stroke for increased grip, or a firmer, more supportive feel that works better for aggressive riding.
The negative spring's air chamber volume can be changed by swapping out the spacer that resides in the Deville's lower left leg.
I was able to get in a few hours of riding on the new Deville, riding the same loop three times in a row in order to try the three different negative spring settings. The test track was moderately steep, with several rougher straightaways that led into compressions, a good way to get an initial feel for the fork. The air pressure was set to 54 psi for my 160 lb weight, with the compression dials clicked into the middle of their range.
The Deville has a very 'open' feeling, tracking every little nuance of the trail and providing excellent traction even on slippery, off-camber sections. It's remarkably close to the sensation you'd expect from a coil-sprung fork, delivering loads of grip without diving or getting sucked into holes.
I tried a different length negative spring rod on each lap and found the difference between the three options to be very noticeable. With the shortest rod in place, which produces the largest negative spring volume, the fork's travel was extremely easy to initiate, allowing it to suck up even the smallest of obstacles, although there wasn't as much support, which made the fork feel a little too soft for my liking. Reducing the negative spring volume provided the support I was looking for, and both the medium and long spacers felt very usable, creating an outstanding plush-yet-supportive feel.
It'll take longer runs and rougher trails to really see how the Deville stacks up against its competitors, but its initial performance was extremely impressive – now we'll just have to see if BOS can provide a level of customer service and support to match.— Mike Kazimer