Fox Float DPX2 Rear Shock Overview: Brand New For 2018

2018 Fox Float DPX2 Rear Shock

Fox has recently announced the release of its new 2018 Float DPX2 rear shock, a shock designed to fill the void between its Float DPS and Float X2 models. According to Fox, its new creation is a hybrid-design that combines the dedicated lockout circuit of the DPS with low internal pressure and a recirculating oil damper architecture found in the X2. In addition, Fox redesigned its EVOL air can by increasing volume for the negative air spring. This air can has a specific size relative to each of Fox’s various offerings for the DPX2.  Combined, these features afford increased small bump compliance and decreased bottoming-out of the rear shock when large jolts are encountered from drops or jumps.

Let’s examine this new shock in greater detail:

DP is an acronym for “Dual Piston”, which features dedicated compression and rebound pistons situated in the base valve, which allow users to make independent adjustments via large blue and red anodized aluminum knobs that are posited opposite to one another on the base valve, which in turn, is positioned perpendicularly on top of the piggy-back reservoir. The large blue compression damping control knob features three positions: Open, Medium, and Firm. Fox recommends Open mode for rough trail descents; Medium mode for undulating terrain; and Firm mode for climbing.

On its Factory versions, while in “open mode”, Fox has added a 10-click adjustment to fine tune compression, which is adjusted by using a 3mm hex key. Clockwise rotation increases low-speed compression damping, while counterclockwise rotation decreases low-speed compression damping. The large red rebound dial has 14 click-settings that afford control over the response time of the shock’s extension after compression. Clockwise rotation increase the shocks rebound damping that slows the shock’s extension speed. Conversely, counterclockwise rotation decreases the shocks rebound damping, which increases the shock’s extension speed. In addition, rebound adjustments are dependent on the air pressure. See Fox’s DPX2 Rear Shock Tuning Guide for detailed information. The size and placement of these knobs makes adjustments a breeze while riding. In addition, both knobs have extremely tactile indents that provide rotational movement feedback, even thru gloved hands.

X2 relates to its ancestry that includes DHX2 and Float X2 rear shocks, which feature a recirculating air flow system that operates under lower internal pressure while offering independent compression and rebound circuitry, enhanced small bump compliance, increased transition control, better heat dissipation, and low hysteresis damping. (Hysteresis is from ancient Greek and means “lagging behind”). This relates to many systems including hydraulics and describes the “lagging of the effect” produced from its cause, the input.

Hydraulic control relates to pressure, flow, torque, displacement; virtually anything wherein some input produces an effect on a system. All of these parameters have their own hysteresis. Typically, an input will produce two outcomes that’s dependent upon whether the source input was decreasing or increasing. Ideally, these parameters have no hysteresis, which would produce high rates of predictability. However, this is highly unlikely as factors like friction and part tolerances/freeplay produce wear-and-tear on parts that results in increased hysteresis. Complicating issues is the tendency of rapid-repeated input to produce increased hysteresis.

In bicycle suspension systems, minimizing hysteresis allows product designers to build shocks with predictable responses when subjected to small bumps and big jolts while riding along rocky terrain, in bike parks, or down mountains. That silky smooth ride is a result of well-engineered control of hysteresis and good body mechanics.)

DPS - This independent circuity allows tuning of the “open” and “mid” modes without affecting the “firm” mode, which allow for increased small bump compliance and a firmer mid-stroke pedaling platform.

EVOL - Represents Expanded VOLume that Fox achieved by enlarging the volume of the negative air pressure chamber versus the volume of the positive air pressure chamber. Fox claims this increases small bump compliance and mid-stroke support. The DPX2’s EVOL air sleeves are specifically designed to match each shock size, and are available in either imperial or metric measurements. Additionally, they have been engineered to minimize friction produced from side-loading and twisting.

Fox has provided five different thickness, plastic volume spacers that allow individualized control over “end stroke ramp” on an air shock. What this means is that as a shock is compressed, air is compressed into a smaller space. Volume spacers occupy some of the available space, therefore, the air is compressed into an even smaller space, which results in increased pressure.

The selection of a larger spacer means that air is compressed into even smaller spaces resulting in greater air pressure. Thus the ending-stroke ramp will be stronger. If you are bottoming-out easily, and your sag has been set properly, install a larger spacer, which will increase bottom-out resistance.

Conversely, if you are not utilizing your shock’s full travel, insert a smaller spacer, which will decrease bottom-out resistance. (Sag relates to the distance your shock compresses under your total weight. Sag range is adjusted to between 25-30% of the shock’s total travel or extension)

Fox’s plastic volume spacers are color-coded with the thickness, in inches, embedded in the spacer. Purple: 0.2”; Gray: 0.4”; Robin’s Egg Blue: 0.6”; Cobalt Blue: 0.86”; Dark Blue: 1.02”. Worthy of note is that the DPX2 rear suspension system allows for the placement of only one spacer at a time; not multiple stacks as in prior models. Installation is straightforward and doesn’t require special tools.

Currently, Fox is offering the DPX2 in the following lengths with air chambers that are individualized for each length: 7.25 x 1.75; 7.5 x 2; 7.875 x 2; 7.875 x 2.25; and 8.5 x 2.5.

The weight for the  DPX2 is 496 grams, but varies by size.

Retail price is $549.

Recap:

• Combines DPS XC efficiency with X2 DH performance
• Dual piston Base Valve features dedicated lockout and compression circuits
• Recirculating damper architecture; better small bump compliance, control, and mid-stroke damping platform
• Available in five sizes with individualized EVOL canister sizes
• Factory series offers 10-clicks compression adjustments in “Open” mode
• Factory series offer Genuine Kashima Coat
• Imperial and metric versions
• Weight 496 grams, but varies by size
• Price: $549

Setting up the DPX2 rear shock:

Sag adjustment:

1. Turn blue knob into “Open” mode
2. Set shock psi to rider weight in pounds
3. Sit on bike and cycle rear shock thru 25% of its travel, 10 times. Leave pump attached
4. Don’t exceed 350 psi
5. Remove pump
6. Support yourself on the bike and pull rubber O-ring upwards, against rubber sleeve seal
7. Dismount smoothly
8. Measure distance between O-ring and rubber air sleeve seal.
9. Compare measurement with Fox’s Suggested Sag Measurements Table
10. Add/remove psi to achieve desired sag

• Equalize positive/negative air chambers by slowly compressing the shock thru 25% of its total travel 10-20 times after every 50 psi addition
• If needed, slowly release excess psi thru the Schrader valve. If adding psi, as before, compress/extend shock thru 25% of its travel 10-20 times

• Blue Knob, Open mode adjustment:
• Turn 3 mm hex key wrench clockwise to increase low speed compression damping
• Turn 3 mm hex key wrench counterclockwise to decrease low speed compression damping
  • Factory series and Performance Elite series only

Rebound Adjustment:

• Red Knob, adjustments dependent on psi setting.
  • Higher psi requires slower rebound adjustment (More clockwise)
  • Lower psi requires higher rebound adjustment (More counterclockwise)
• Turn red knob completely clockwise, then turn counterclockwise to desired setting

• 5 sizes, first set proper sag before proceeding
• If shock bottoms out readily, insert a larger spacer
• If shock’s full travel not used, insert a smaller spacer
• System designed to handle one spacer at a time

Fox’s instructions are easy to follow and will have you up and running in no time.