FORK- 2014 34 831 26

FORK- 2014 34 831 26


3.9 inches / 100 mm


Factory FIT CTD w/Adj; 100; Kashima Coated upper tubes, 1.5" tapered steerer, lever actuated Climb/Trail/Descend (3 position), Trail adjust range (1, 2, 3), rebound, air spring pressure. 

Lower leg

15QR thru axle system, post style disc brake mounting



Riding style

DJ/4X, Trail

For general information and installation instructions click here »  

Before You Ride

Make sure that your fork is ready to ride

  1. Check that quick-release levers are properly adjusted and tightened.
  2. Inspect the entire exterior of your fork. The fork 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.
  3. Check your headset adjustment. If loose, adjust it accordingly to your bicycle manufacturer's recommendations.
  4. Check that all brake cables or hoses are properly fastened.
  5. Test the proper operation of your front and rear brakes on level ground.
  6. Before every race or ride, clean the outside of your fork with only mild soap and water, and wipe dry with a soft dry rag. Do not spray water directly into the seal/upper tube junction. Do not use a high pressure washer on your fork.

Setting Fork Air Pressure

Setting sag is desired and necessary for proper fork performance during general XC/Trail riding. The 831 fork is not intended for general XC/Trail riding use, but for four cross racing, slalom, or dirt jumping. Therefore, the air pressure is generally not set by obtaining proper sag, but is intended to be set for proper riding feel and bottom out control. 

34 FLOAT maximum air pressure is 125psi

Sag should be set to 15 – 20% of total fork travel

  1. Unscrew the blue air cap on top of the left fork leg to expose the Schrader valve.
  2. Attach a FOX High Pressure Pump to the Schrader valve.
  3. Pump your fork to the appropriate starting point from the Suggested Air Spring Pressure Settings table below, then remove the pump.
  4. Unless your fork already has a sag setting o-ring on an upper tube, temporarily install a zip tie to an upper tube. Slide the o-ring (or zip tie) down against the scraper lip of the fork dust wiper.
  5. Rotate the CTD lever to the Descend mode (the riders 1 o'clock position).
  6. Dressed to ride (including a filled hydration pack, if you use one), position your bike next to a wall or table to support yourself. Mount your bicycle. Assume your riding position for at least 10 seconds, allowing the suspension to fully settle. Make sure you distribute your weight evenly between the saddle, handlebars and pedals.
  7. While in your riding position, slide the o-ring (or zip tie) down against the fork dust wiper.
  8. Dismount your bike without bouncing, to avoid further moving the o-ring or zip tie. Measure the distance between the dust wiper and the o-ring or zip tie. This is your sag measurement. Suggested sag measurements are listed in the table below.
  9. Add or remove air pressure until your sag measurement is between 15-20% of your forks total travel.
  10. Repeat steps 2-8 and recheck sag measurement.
  11. When sag measurement is correct, screw the blue air cap on clockwise until snug.

Suggested Starting Points for Setting Sag
Rider Weight lbs/kgs 100mm
≤125 ≤57 55psi
125 - 135 57 - 61 60psi
135 - 145 61 - 66 65psi
145 - 155 66 - 70 70psi
155 - 170 70 - 77 80psi
170 - 185 77 - 84 85psi
185 - 200 84 - 91 90psi
200 - 215 91 - 98 100psi
215 - 230 98 - 104 110psi
230 - ≥250 104 - ≥113 120psi


Suggested Sag Measurements
Travel 15% sag (Firm) 20% sag (Plush)
3.9 in./100mm .58 in./15mm .78 in./20mm

Adjusting Rebound

Rebound controls how fast the fork extends after compressing


The red rebound adjuster is located at the bottom of the right fork leg. Rebound controls the rate of speed at which the fork extends after compressing. Turning the knob clockwise (in) slows down rebound; turning the knob counter-clockwise (out) speeds up rebound. Rebound damping should only be set after first setting your air pressure by measuring sag.

  1. Make sure your CTD fork is in Descend mode (fully counter-clockwise).
  2. Starting with the rebound adjuster fully open (counter-clockwise) push on the fork to compress it and feel its return speed.
  3. Increase rebound damping by turning the red rebound knob in clockwise until when tested, the fork returns quickly but does not top out.

Top out is felt when a fork fully extends too quickly and comes to an abrupt stop when it reaches full extension (you will hear/feel a small noise). Top out should be avoided through proper rebound setting.

Climb, Trail, Descend

Easy on-the-fly adjustments for unprecedented control and performance

The blue CTD lever lets you to switch between the Climb, Trail, and Descend modes. Each mode is optimized for each specific type of terrain, providing exceptional performance and riding enjoyment with your fork. CTD allows for complete rider control as one can experiment using different modes on various different types of terrain.


Climb Mode:


Rotate the blue CTD lever fully clockwise to set the fork in Climb mode. Climb mode is a very firm low-speed compression setting (not designed to be a solid lockout). This setting is most useful for climbing and sprinting.


Trail Mode:


Rotate the blue CTD lever to the middle setting to set the fork in Trail mode. Trail mode offers less compression damping than Climb mode. Use this setting when pedaling on undulating terrain, and for preventing excessive travel in technical riding situations (such as low-speed drops). Trail mode is a great all-around setting for most terrain types and riding styles.


Descend Mode:


Rotate the blue CTD lever fully counter-clockwise to set the fork to Descend mode. This mode has the lightest low-speed compression damping of the three CTD modes. Descend mode offers the most plush ride to ensure optimal traction over varied terrain.


Adjusting Trail Mode

FIT CTD w/Trail Adjust models allow for added fine tuning

trail-soft.jpg trail-medium.jpg trail-firm.jpg

Factory CTD w/Trail Adjust model forks feature a three-position Trail Adjust control that regulates low-speed compression damping only in Trail mode. For firmer low-speed compression in Trail mode, turn the black Trail Adjust knob clockwise. For lighter low-speed compression, turn the Trail Adjust knob counter-clockwise.

Trail adjustments (soft, medium, firm) only function in Trail mode.

Service Intervals

Make sure to properly maintain your fork

service intervals air fork.jpg


Dealer, Distributor, and OEM access


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