The Cartridge Specs
First up it Is a hydraulic damping cartridge. The kit includes two cartridges both of which are identical. The damper works with two pistons, one for compression, the other for rebound. Each piston has a shimmed setting, which allows the owner to modify the hydraulic curve. You can adjust compression and rebound (external) and also the spring pre–load, by removing the upper caps. The travel is also adjustable without having to change the cartridge, from 170 to 200mm.
Fitting the cartridges is straightforward requiring no particularly special tools other than some big spanners. Out with the old, slip off the springs and then onto setting the height of the fork. We opted for the 180mm travel approach and set the spacers to suit. To do this requires you to push in the piston on the lower part of the cartridge that exposes a spring clip. Pop this off, slip in the spacers and replace clip. Then, drop in the new cartridge and screw on the compression adjuster on the lower of the legs (like the Fox) before inserting the bearings for the adjuster and tightening. Fill with oil, not just any oil bought and labelled as something special, but BOS oil blended by their own chemist and for mountain bike application…being light, reducing friction and lasting longer…tops on and away.
Having the cartridges only a week before deadline it wouldn’t really be right to draw any conclusions even. Not surprisingly though the cartridge impressed us with its precision and fit. Having two compression and two rebound adjusters did take time to set up but then this is for people who do just that, take time to get suspension right. On track the grip is quickly apparent and the advantage of being able to run less travel without your wheels digging into the ground is even more obvious. The BOS/Marzocchi gives an altogether different ride characteristic to the standard fork, and you will notice a sudden ability to turn on the front wheel with confidence. We have also just received Fox DHX from Bossard, which with the BOS/Marzocchi could be the high performance set up. Full review in issue 53. In the meantime, if you think you can trust someone who has not only many World Championship Downhill winners but has designed suspension on Paris Dakar winning bikes and cars then maybe you should just ring them. SJ
Contact: BOS Engineering + 33 (0) 534 25 33 66
You can adjust compression and rebound (external) and also the spring pre–load, by removing the upper caps. The travel is also adjustable without having to change the cartridge, from 170 to 200mm.