Andres

Cane Creek Double Barrel Instructions
Congratulations on your purchase of the Cane Creek Double Barrel (CCDB) rear shock. Developed in partnership with Öhlins Racing, the Double Barrel brings revolutionary suspension technology to the bicycle market. For nearly three decades, Öhlins Racing AB, based in Stockholm, Sweden, has produced high-performance suspension systems for the elite teams in alldisciplines of World Class motor sport racing. Sharing the precision quality and exceptional performance that is inherent in Öhlins’ designs, the Double Barrel is designed for performance in extreme off road conditions. The unique Twin Tube design incorporated in the CCDB offers the broadest adjustment range available in suspension. The CCDB’s adjustment features give you the control to tune theshock your way for your bike. Enjoy the ride. Caution: Reading and following the set-up instructions carefully and methodically is critical. Incorrect tuning can produce poor results or even dangerous riding performance. See pages 5 & 6 for key set-up instructions. Design Background: Most shock absorbers are the De Carbon type (figure 1). These shocks separate the gas from the oil with a dividingpiston, usually located in a remote (or piggy back) reservoir. Primary damping takes place via the main piston by using a shim stack. The shim stack resists the flow of oil though the ports on the piston. Stiffer shims yield more resistance; and, thus, more damping force. Some oil is also displaced by the shaft entering the body chamber. This oil flows out to the reservoir where the expansionchamber can accommodate it. When the shock rebounds, this oil returns to the main chamber by the same route. Variations of this style of shock will incorporate external adjusters to control the damping characteristics. The most common adjustment controls the rebound damping. A small needle valve running through the center of the piston shaft controls the flow of oil as the shock

Figure 1: De Carbontype
03/07/08

Figure 2: Twin Tube type
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Figure 3: Low speed bleed valve.

Figure 4: High speed poppet valve.

extends. In some designs adjusters are added to the reservoir passage as well. The De Carbon style shocks function very well if adjusted properly. Unfortunately, the external adjusters are limited in their Figure 5: Main piston shim stack. range. The rebound bleedvalve works primarily on low speed damping. Thus, it has little effect on high speed movement. Also, external adjusters on the reservoir have little effect. The reason is that they dampen only a small percentage of the oil—only the oil displaced by the piston shaft. Some designs will try to increase the effect by using larger piston shafts, but this has a negative effect on the pressure balanceand performance of the shock overall. So, to achieve the best characteristics, the shock must be disassembled and re-valved for each specific application—not an easy task. The Twin Tube technology (figure 2) incorporated in the Double Barrel shock is different. Rather than pumping only displaced oil back and forth to the reservoir, the oil circulates continuously through the valving to achievehighly controllable, independent damping. There are three distinct damping features in the CCDB for both the compression and rebound strokes. The low speed adjusters (figure 3) consist of needle style bleed valves that control the flow of oil when the shaft is moving slowly. Turning the slotted screw varies the size of the orifice through which the oil flows. A larger orifice allows more oil flow and,thus, more suspension movement for slow speed travel. The high speed adjusters are poppet style valves (figure 4) that open once the pressure from the oil flow is significant enough. Turning the hex adjusters varies the spring preload behind the poppet and determines the opening force. Finally, the main piston in the shock has both a compression and rebound shim stack (figure 5). These control...