French brand BOS has a successful history in mountain bike racing and a reputation for high-end performance. Its Deville fork has 34mm stanchions and uses a combined 20mm/15mm clamped axle system to fit both hub sizes. The fork arch sits lower than most — tall 2.4in tyres run tight against the brace affording less mud clearance,
and it’s harder to fit some mudguards. The Deville is one of the heavier forks here, but the chassis feels twist-free and very solid. BOS also has a 200g lighter all-mountain model coming with a 15QR instead of the clamped axle.
The Deville uses an open-bath design rather than a sealed-cartridge damper with three forms of adjustment — high and low-speed compression and rebound — all of which have a very wide and effective range. The self-balancing (positive and negative) air spring needs to be cycled a few times first time out to work properly, but then it rests 5mm or so into the sag, presumably to increase the small-bump sensitivity.
Even with the recommended settings, there’s class-leading sensitivity and tracking, almost to the point where the fork feels too quick and soft and isn’t going to support you when the going gets rough… but it always does. Grip at the front tyre is superb — the wheel traces over the terrain and is in near-constant contact, informing you exactly what’s going on and enabling the carving of tighter lines without washing out.
In terms of damping, it’s never anything less than composed regardless of the terrain or steepness, and you continue to feel the ground even deeper in the stroke. There’s a sensation with this fork that you can ride faster (which is what matters to most people) by reacting quicker to the conditions under the wheel that get fed back in a calm and controlled way.
The suppleness and control makes the Deville fork feel the most comfortable too — the damper takes energy out of impacts with a smooth response that doesn’t feed back too much harshness, yet still gives plenty of support to push into when hitting lips, jumps and berms.
Our only gripe was that the decals on the lowers tear too easily, which is poor for a fork costing £950, and the rebound stroke is a little wheezy and noisy. BOS has suffered patchy aftermarket service in the UK in recent years but with a new importer we’re hoping those service issues should be thing of the past.
We certainly haven’t had any problems with this fork — reliability has
been absolutely spot-on.
The BOS feels like a precision instrument with huge potential for tuning. The machining details (and even the damper sound) have a bespoke race vibe, and an action so responsive and sensitive it's remarkable how stable it remains on the roughest trails. BOS forks can bob a little while cranking out of the saddle on flatter trails, or climbing, but set-up correctly, you simply cant's get the same level of grip and comfort anywhere else.