The boost valve is a position sensitive valve that adds
more compression as the shock compresses, this is good in theory for
but a problem occurs when the shock encounters high speed curb style
bumps deep in the stroke, this is when the boost valve is adding more
whereas the speed sensitive valve will relieve this compression and
make the bump feel smoother and prevent the high speed hydraulic lock
that the boost valve creates.
The boost valve is removed and replaced with a custom tuned speed sensitive
shimmed valving stack to give you big bump absorption with high speed
square edged plushness.
The stock Float shock has been designed for more of
a platform feel, and the lever creates more or less pedal performance,
so this platform feel, created by the boost valve, requires more force
to overcome the threshold of the boost valve.
In other words the shock does not compress easily over small bumps and
provides better pedal performance.
The SSD/HSB conversion takes
a different approach to the shock adjustment.
Descend/Pedal SSD/HSB low speed Threshold option
Our goal is to create a downhill version of this shock, so we concentrate
on setting the valving(SSD) for the frame leverage and terrain and put
the pedal platform(HSB) feel in the adjustment. This allows us to create
a plusher, smoother feeling shock without the harshness that was created
by the boost valve of the stock internals.
We use the existing lever system to provide adjustment to the modified
internals, for the RP23 it now acts like a 4 position low speed threshold
adjust system. The firmest position “on 3” will be used
for pedaling or the firmest threshold. For the CTD it now acts like
a 5 position low speed threshold adjust system. The "descend"
will be the softest setting and the "trail" position will
give you fine tuning with the 1, 2 3 adjust positions. The firmest position
“climb” will be used for pedaling or the firmest threshold.
We are creating multiple settings for trail/DH riding that allows for
fine tuning of the low speed compression for that plusher DH feel. In
other words, we are starting with the Trail 2/On 1 position as the standard
setting rather than the Descend/Open position. All positions provide
pedaling performance without sacrificing medium and high speed bump
absorption because the HSB adjustment is independent of the main valving
system.The firmer the position the more the low speed threshold is increased,
this creates more low speed compression that can still blow-off at varying
rates depending on the lever position. The Climb/On 3 position provides
the best pedaling performance without sacrificing medium and high speed
bump absorption because we isolate the main valving from the climb adjustment.
In other words, it is no longer a lock-out design, but now the firmest
low speed threshold position, that can still blow off on medium and
Pedal only/Firmer SSD/HSB low speed Threshold option
We do offer the same service for a less active/firmer pedal feel. This
SSD/HSB option offers firm high speed square edged feel but with a less
noticeable low speed blow-off to provide better pedal performance in
the trail and climb positions. Small bump performance will be compromised
to provide a firmer low speed feel, this is only recommended when pedal
performance is more important than small bump downhill plushness. Trail
or cross country only, not recommended for descending. This option isrecommended
for riders looking for that cross-country feel, you will have to sacrifice
downhill performance for pedaling resistance, as the valving is not
set-up for downhill performance, the valving is optimized for resisting
pedal forces, all positions of adjustment are designed for pedaling.
Great news for
Evolution and Performance non-BoostValve
here for more details to order
are pleased to announce our SSD/HSB conversion kit that makes your Evolution/Performance
shock internally similar to the Factory CTD/Performance/RP23 BoostValve
shocks. price $229.
above is the SSD/HSB conversion kit for Evolution/Performance Non-BoostValve
Evolution/Performance Non-BoostValve series shocks were not compatible
with our SSD/HSB mods, as they have no low speed compression threshold
adjustment circuit and no rebound valving to revalve.
Converts CTD lever to Firm setting(Climb),
3 Medium settings(Trail) and Soft setting(Descend) settings of HSB compression
Converts ProPedal lever to 3 trail settings(on position) and one soft
setting(off position) settings of HSB compression adjustment.
The low speed circuit is converted to our HSB
system, this allows for a
increased low speed compression threshold that still blows off on small
to create that small bump plushness without the harsh feel.
The HSB also provides for a smooth transition of low
to the main piston valving shim stack.
High and mid speed compression system is controlled by the custom valved
speed sensitive shimmed compression main piston. This is set-up to match
the leverage and rider terrain.
Check valve systems are optimized to prevent the compression
and rebound adjustments from affecting each others, thereby isolating
the adjustments to a independent feel.
Mid and high speed rebound is controlled by a custom
valved shim stack to match the riders weight
(air can pressure) and the leverage of the frame.
Low speed rebound can now be fine tuned by the red rebound knob,
i.e. more usable positions rather than coarse tuning for air pressure.
Includes custom revalve and setup for rider, frame
leverage and conditions
and printed set-up chart.
We will recommend the air can size and air can spacer if needed
Optional ABS(anti-bottoming system) available for more aggressive and
bigger riders or smaller riders on regressive linkage frame.
Also includes complete rebuild service, oil, nitrogen
charge and typical wear parts* included in price.
New lower friction, higher temperature shaft seal and
IFP seal, and more reliable IFP charging puck.
*(Typical wear parts: shaft seal, reducer DU bushings, and o-rings)
**The shock must be in good working condition with no
scratches or dents on moving parts, if the air can is leaking, it should
also be noted that air side will not be modified in anyway and any air
side issues will not be addressed. (Air can rebuild parts not included,
self-install from Fox only)
Service interval will remain the same as before the modifications)
Typical Float CTD SSD Modified Shaft Piston Assy
Float Performance Series BoostValve CTD