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Specialized®IV Shocks with Autosag

General Maintenance | Setting Autosag | Adjusting Rebound | Adjusting Brain Fade™ | Before You Ride | Important Safety Information


Autosag air sleeve, inertia valve damping, lightweight chassis, Brain Fade™ adjust, air spring pressure, rebound adjust, Autosag



intended use

all-mountain, cross-country

The IV rear shock family is supplied as original equipment (OE) with the following Specialized® bicycle models:

Setting Autosag

  1. Turn the Brain Fade™ and rebound adjustment knobs all the way counter-clockwise, to their minimum position.
  2. Slide the travel indicator o-ring on the shock body to the dust wiper lip.

  3. Ideally with all your riding gear (don't forget your water bag if you're using one), mount your bicycle next to a counter or wall to steady yourself, letting your full weight settle into the saddle as it normally would when you are riding.
  4. Remove the cap to the black air valve. Attach your FOX high pressure hand pump and fill the shock to 300 PSI.

    Note:  Heavier riders have the option to fill the shock to 350 PSI. To attain this pressure however, using the Specialized® high pressure hand pump is required, as going over 300 PSI with the FOX high pressure hand pump may cause damage to the gauge.

    CAUTION:  Regardless of your initial PSI level, BEFORE you ride, always make sure that you release this level to your total weight by pressing the red air release valve, as shown in steps 5 through 7 below.

  5. Remove the red air release valve cap and keep it where you won't lose it.

    CAUTION:  The red air release valve cap is specially sized. Never under any circumstances attach your pump to the red air release valve and attempt to pump any air into the shock. Doing so will cause irreparable damage to the red release valve.

  6. Reach down and depress the red air release valve until the hiss of releasing air pressure completely stops.

  7. Replace the red air release valve cap. You are done, ready to ride with sag properly set for your total weight.

Adjusting Rebound

Rebound controls the rate at which your shock returns after it has been compressed. The proper rebound setting is a personal preference, and changes with rider weight, riding style, and terrain. A basic rule of thumb is that rebound should be as quick as possible without kicking back hard, bucking you off the saddle.

The rebound knob has 12-15 clicks of adjustment.

For slower rebound, turn the red adjuster knob clockwise.

For faster rebound, turn the red adjuster knob counterclockwise.

Adjusting Brain Fade™

All IV rear shocks are equipped with Brain Fade™ technology, which gives you the ability to adjust your shock from firm to plush to match your riding terrain. The inertia valve automatically switches from your pre-adjusted Brain Fade™ setting to a fully plush feel when the rear wheel hits a bump.

For a firmer ride setting, turn the Brain Fade™ adjustment knob clockwise.

For a softer ride setting, turn the Brain Fade™ adjustment knob counterclockwise.

Before You Ride

  1. Inspect the entire exterior of shock; the shock should not be used if any of the exterior parts appear to be damaged. Contact your local dealer or FOX for further inspection and repair.
  2. Check that quick-release levers (or thru-axle pinch bolts) are properly adjusted and tightened.
  3. Check that your headset is properly adjusted. If it's loose, adjust it accordingly to the manufacturer’s specifications.
  4. Check that brake cables or hoses are properly fastened and adjusted.
  5. Check that the front and rear brakes operate properly on flat land.

General Maintenance

Note:  IV rear shocks are not 100% user serviceable, meaning that if seals are found to be in need of replacement, this level of service must be performed by FOX service, or by an Authorized FOX Service Center.

You can:

Bushing Technology & Inspection |  | Oil Volumes | Dropout Thickness Inspection | Using the FOX HP Pump | Important Safety Information | Service Intervals | Contact FOX Service | FOXHelp Service Web Site