Tech Help - RBC TUNE
FOX CTD BOOST VALVE AND RP SERIES SHOCKS
Thinking about having your Shock tuned?
What difference does a RBC tune make to the feel and ride of your shock?
STANDARD FOX CTD, BOOST VALVE & RP SERIES
When a standard FOX RP or CTD boost valve series shock compresses, the oil in the damper travels through two different paths.
The first path (low speed) is through the centre of a bolt which holds a piston to the damper shaft. The damper shaft is housed within the shock body (the grey or gold anodised part of the shock). The oil flow through this central port can be stifled by a bullet tipped poppet valve when the rider activates the ProPedal lever. This is what provides you with a platform.
The second path for oil is to travel through ports in the piston (mid-high speed).
Once through the ports, the oil is controlled either by a penny washer which is preloaded by 1,2 or 3 conical washers to give you soft, medium or firm compression or on a more recent boost valve products, a hydraulic valve is used. The oil is forced against the piston ports by a charge of nitrogen (boost valve pressure). Variations in this pressure provide you with different levels of compression resistance.
When the low speed oil flow has overcome resistance from the poppet valve, the washers or boost valve behind the piston provide the blow-off threshold of the platform. The washers or boost valve don't offer a great degree of control for the oil, and the riders’ experience is that the shock feels initially harsh, and then ‘wallowy’ in its stroke. This suspension ‘wallow’ is accentuated with large volume air cans.
This standard shock configuration means that there are only a few different compression settings available to accommodate every rider and every bike linkage/leverage.
RBC TUNED FOX CTD, BOOST VALVE & RP SERIES
When your shock is tuned at RBC, the piston is replaced with the RBC V3 version, which has larger ports to allow more oil flow.
We then use our expertise and the individual customer’s ride preferences to configure a stack of up to 30 shims each 1 1/10 of a mm thick. The RBC shims control the flow of oil from the very beginning to the very end of the compression stroke, offering a ride characteristic which is completely customised for your frame and riding style.
The ProPedal feature of the shock still remains, but in a better form, because we can alter the resistance from the poppet valve to offer more or less platform, depending on your requirements.
The V3 piston also has larger ports for high speed rebound, allowing us to customise the rebound speed to return quickly after successive hits without being like a pogo stick.
The end result is a shock which tracks the ground far more smoothly, responding to small bumps actively and giving an ‘endless’ feeling travel, whilst retaining a good level of resistance to pedaling when the ProPedal lever is actuated.
After this customised damper circuit has been configured, we can also offer the BIG HIT KIT to provide a very gradual bottom out control for more extreme applications. This extra option is particularly useful for riders using shocks with a large volume air can.