After a couple of months spent riding the BOS Kirk rear shock, we’ve had to completely recalibrate our whole concept of what mountain bike suspension is capable of. BOS has now taken the same damper found in the Kirk and miniaturized it to fit inside an as yet unnamed prototype XC shock made for bikes with up to 120mm of travel.
With a size that is similar to the air can/shaft assembly of the Specialized/Fox Mini Brain shock, the diminuitive size of the new BOS shock belies the serious performance that it promises. And, at less than 190 grams, it’s a contender for the lightest oil damped rear shock on the market.
A three-position switch allows riders to toggle between open, pedal, and climb modes with the same large lever found on the Kirk. BOS confided that both a cable actuated and an electronic remote option are in the works. A red bolt on the opposite side of the shock from the mode select lever covers the access port that the factory uses to tune the shock curve and damping characteristics. While this adjustment will not be user tunable, it does make custom tuning at the factory a relatively simple operation.
Like all BOS Suspension, sensitivity was the highest priority in the development of the shock. This is a big departure from the philosophy espoused by most XC riders that do whatever they can to reduce suspension sensitivity—even if it means sacrificing descending performance. But the proof is to be had out on the trail. The advanced damper that this new shock is built around instantaniously adapts to provide the support needed as pedaling inputs and trail obstacles activate the suspension. A team rider that took the prototype shock out for an initial parking lot test ride came back to BOS owner Olivier Bossard to complain that the shock was too soft. Olivier replied, “Go ride it on the trail and then come back and tell me if you think it is too soft.” With the on trail test ride complete, he reported back that the shock was just right.
World-beating low weight, XC pedaling performance, but with DH sensitivity and high-speed compression support? I think we may have found the suspension holy grail. Given our experience, if the new shock is even half as good as the Kirk, it will be an upper deck home run.