FORK- 2021 36mm/38mm

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 and axle pinch bolts of the bike 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.


Mounting Disc Brakes

WARNING: Follow your brake manufacturer's installation instructions for proper installation and adjustment of the brake system. Failure to properly install and adjust your brakes can lead to a loss of control of the bicycle which can result in SERIOUS INJURY OR DEATH.

The 2021 36mm and 38mm FLOAT forks use 180mm Post Mounts that allow you to bolt your caliper directly to the fork and utilize a 180mm rotor. This post mount eliminates the need for a caliper adaptor when using the most common 180mm rotor size for forks with these amounts of travel, which saves overall system weight. 

 

If your current 180mm brake setup came with bolts and a caliper spacer, you may need to source shorter bolts as you will not need a caliper spacer when using a 180mm rotor.

 

If using a 203mm-230mm rotor, you will need to source the appropriate caliper spacer and bolts. Contact the brake manufacturer for further information.

 

brakes-36-38.jpg

 

 



Installing the Front Wheel (15mm or 20mm Pinch Axle)

Install Your Wheel Correctly to Benefit From the Floating Axle

15QR Installation:

1. Loosen the pinch bolt, then install the front wheel into the fork dropouts. Slide the axle through the drive side dropout and hub.

2. Open the axle lever and pinch bolt.

3. Turn the axle clockwise 5-6 complete turns into the axle nut.

4. Close the lever. The lever must have enough tension to leave an imprint on your hand.

5. The closed lever position must be between 1-20 mm in front of the fork leg.

6. If the lever does not have enough tension, or has too much tension when closed at the recommended position (1-20 mm in front of the fork), see the next section for adjustment instructions.

7. Compress the fork a couple of times to ensure that the lower leg has settled into its low-friction point.

8. Tighten the pinch bolt on the drive side dropout to 5.1 Nm (45 in-lb) torque.


IMPORTANT: You will only need to tighten the pinch bolt during your first wheel installation. After tightening the pinch bolt, you may remove the QR axle and replace it without loosening or retightening the pinch bolt. If you are changing wheels or hubs, it is likely that the pinch bolt will need to be adjusted by following these installation instructions starting at step 1.

 

36-38-15qr.jpg

 

 

Adjusting The QR:

1. Note which direction the axle lever needs to turn to achieve proper orientation.

2. Open the axle lever in the fork.

3. While holding the QR lever open and stationary so it cannot rotate, use a 4 mm hex wrench in the center of the end of the axle to adjust the lever position. With the 4 mm adjuster set properly, you should start to feel tension in the axle when the QR lever is 90 degrees before full closure in the vertical position.

4. Repeat the axle installation instructions to verify proper installation and adjustment.

 

KaboltX Installation:

NOTE: KaboltX is only compatible with the 2021 36 and 38 forks.

1. Loosen the pinch bolt, then install the front wheel into the fork dropouts. Slide the KaboltX axle through the drive side dropout and hub.

2. Use a 6 mm hex wrench to torque the KaboltX axle clockwise to the torque specification that is etched on the head of the Kabolt.

3. Compress the fork a couple of times to ensure that the lower leg has settled into its low-friction point.

4. Tighten the pinch bolt on the drive side dropout to 5.1 Nm (45 in-lb) torque.

 

kaboltx.jpg



Setting Fork Air Pressure

2021 36 FLOAT maximum air pressure is 120psi (8.3 bar)

2021 38 FLOAT maximum air pressure is 140psi (9.6 bar)

NOTE: Pressure measured at an ambient temperature of 70-75˚F. Normal operating temperature range for FOX products is 20-140˚F.

Depending on variables such as riding style, terrain, bike geometry, etc, you may find that you can only achieve proper sag and ride performance with up to 10psi over or under the recommended value in the suggested starting pressure chart below. Feel free to experiment with fork air pressures using the information below as a guide.

Setting sag is desired and necessary for proper fork performance during general XC/Trail/AM riding. The 831 fork is not intended for general XC/Trail riding use, but for four cross racing, slalom, slope-style, 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. 

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

To achieve the best performance from your FOX suspension, adjust the air pressure to attain your proper sag setting. Sag is the amount your suspension compresses under your weight and riding gear. Sag range should be set to 15–20% of total fork travel.

 

  1. Unscrew the air cap on top of the left fork leg counter-clockwise to expose the Schrader valve. 38-36-sag.jpg
  2. Attach a FOX High Pressure Pump to the Schrader valve.
  3. Pump your fork to the appropriate pressure as listed in the 'Suggested starting points for setting sag' table below, then remove the pump.
  4. Using your forks sag setting o-ring on the left upper tube (or temporarily install a zip tie to the upper tube), slide the o-ring (or zip tie) down against the fork dust wiper.
  5. Make sure that your compression adjusters are in the Open position
    • Rotate the compression lever to the Open mode (fully counter-clockwise).
    • If you have a 3-Position Remote fork, set the fork to Open mode.
    • If you have LSC or HSC/LSC adjust, make sure all adjusters are open (fully counter-clockwise.
  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 air cap on clockwise until snug.

 

 

 

 

Suggested Sag Measurements
Travel 15% sag (Firm) 20% sag (Plush)
130mm/ 5.1 in 20mm/ 0.8 in 26mm/ 1.0 in
140mm/ 5.5 in 21mm/ 0.8 in 28mm/ 1.1 in
150mm/ 5.9 in 23mm/ 0.9 in 30mm/ 1.2 in
160mm/ 6.3 in 24mm/ 0.9in 32mm/ 1.3 in
170mm/ 6.7 in 25mm/ 1.0 in 34mm/ 1.3 in
180mm/ 7.1 in 27mm/ 1.1 in 36mm/ 1.4 in

 

 

Suggested Starting Points For Setting Sag 36mm
Rider Weight (lbs) Rider Weight (kgs) FLOAT Pressure (psi) FLOAT E-Bike+ Pressure (psi) Rhythm Pressure (psi)
120-130 54-59 66 71 55
130-140 59-64 70 76 59
140-150 64-68 74 81 63
150-160 68-73 78 85 67
160-170 73-77 82 90 72
170-180 77-82 86 95 76
180-190 82-86 89 99 80
190-200 86-91 94 104 85
200-210 91-95 99 109 89
210-220 95-100 105 113 93
220-230 100-104 109 115 97
230-240 104-109 113 117 102
240-250 109-113 117 120 106

 

Suggested Starting Points For Setting Sag 38mm
Rider Weight (lbs) Rider Weight (kgs) FLOAT and E-Bike+ Pressure (psi)
120-130 54-59 72
130-140 59-64 76
140-150 64-68 80
150-160 68-73 84
160-170 73-77 89
170-180 77-82 93
180-190 82-86 97
190-200 86-91 102
200-210 91-95 106
210-220 95-100 110
220-230 100-104 114
230-240 104-109 119
240-250 109-113 123

 

 



Adjusting Rebound

Rebound controls how fast the fork extends after compressing

The rebound adjustment is dependent on the air pressure setting. For example, higher air pressures require more rebound damping.

GRIP2-REBOUND.jpg

Use your air pressure to find your rebound setting. Turn your rebound knob to the closed position (full clockwise) until it stops. Then back it out (counter-clockwise) to the number of clicks shown in the table below.

 

Rider Weight (lbs) Rider Weight (kgs) 36/38 FIT4 36/38 GRIP 36/38 GRIP2
LSR HSR
120-130 54-59 14 13 9 8
130-140 59-64 13 12 8 7
140-150 64-68 12 11 7 6
150-160 68-73 11 10 7 6
160-170 73-77 9 9 6 5
170-180 77-82 8 8 6 5
180-190 82-86 7 7 5 4
190-200 86-91 6 6 4 3
200-210 91-95 5 5 4 3
210-220 95-100 4 4 3 2
220-230 100-104 3 3 2 1
230-240 104-109 2 2 2 1
240-250 109-113 1 1 1 0

 

Rebound-open-closed.jpg

Adjust rebound 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.

 



Factory and Performance Elite FIT4 Compression Adjusters

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

3-Position Lever: The 3-position lever is useful to make on-the-fly adjustments to control shock performance under significant changes in terrain, and is intended to be adjusted throughout the ride. You can use the OPEN mode during rough descending, the MEDIUM mode for undulating terrain, and the FIRM mode for smooth climbing.

FOX recommends beginning with the 3-position lever in the open mode.

32-3-pos.jpg

 

*OPEN Mode Adjust: Open mode adjust is useful to control fork performance under rider weight shifts, G-outs, and slow inputs. OPEN mode adjust provides 22 additional fine tuning adjustments for the OPEN mode. Setting 22 will have a more plush feel and setting 1 will have a firmer feel.

FOX recommends beginning with the Open mode adjust set to 18 clicks out (counter-clockwise) from fully closed (clockwise).

32-open-mode-adjust.jpg

32-open-mode-range.jpg

 

*Factory and Performance Elite Series forks only.



Factory and Performance-Elite Series GRIP2 Compression Adjusters

Independently Control High and Low Speed Compression

Adjusting your high and low speed compression setting controls how the fork feels as it's compressed through its travel under various types of hits. Use your high and low speed compression adjusters to tune the fork to meet your riding style and terrain.

High-speed compression (HSC) adjustment is useful to control fork performance during bigger hits, landings, and square-edged bumps.

GRIP2-HSC-knoba.jpg

Low-speed compression adjustment is useful to control fork performance during rider weight shifts, G-outs, and other slow inputs.

GRIP2-LSC-knoba.jpg

 

FOX recommends turning adjusters fully clockwise until they come to a gentle stop (approximately 2 in-lb/ 0.2 Nm torque) then turning counter-clockwise to the recommended setting. Any High-Speed Compression settings beyond 16 clicks out from fully closed do not change damping. While the HSC adjuster may have more than 16 detent clicks, only the 16 positions closest to fully closed are designed for use. Any clicks beyond 16 out from fully closed are due to the configuration of the adjuster and will not affect performance in any way.

 

FOX recommends beginning with the High-speed compression set 5 clicks out (counter-clockwise) and Low-speed compression set 10 clicks out (counter-clockwise) from closed (full clockwise). 

40-grip2.jpg 

 

 



Performance Elite LSC Compression Adjuster

Adjusting your low-speed compression setting controls how the fork feels as it's compressed through its travel under various types of hits. Use your low speed compression adjusters to tune the fork to meet your riding style and terrain.

 

Low-speed compression (LSC) adjustment is useful to control fork performance during rider weight shifts, G-outs, and other slow inputs.

GRIP-knob.jpg

 



Adjusting GRIP Compression Damping

3-Position Micro Adjust: The 3-position lever is useful to make on-the-fly adjustments to control fork performance under significant changes in terrain, and is intended to be adjusted throughout the ride. Turning the lever to the full counter-clockwise position sets the fork in the Open mode. Turning the lever to the middle detent position sets the fork in the Medium mode. Turning the lever to the full clockwise position sets the fork in Firm mode. The positions between the Open, Medium, and Firm modes can be utilized to fine tune your compression damping. 

FOX recommends beginning with the 3-position lever in the Open mode.

  

Grip-lever-image.jpg



Remote Installation

The 2-Position remote can either be installed under the handlebar on the non-drive side, where a front shifter would typically be placed, or installed above the handlebar on the drive side. The 2-Position remote can be used with two cables to control both Push-to-Unlock forks and shocks simultaneously. The 3-Position remote can be installed in-line with the handlebar on either side and can control the fork or shock.

 

FIT4 DAMPERS (Push-to-Lock and Push-to-Unlock)

  1. Install the remote lever onto your handlebar. Do not exceed 1.7 Nm (15 in-lb). Less torque may be needed for carbon bars. Refer to the handlebar manufacturer’s instructions for use with carbon bars. Make sure to check for clearance between the remote lever and any brake or shifter controls.
  2. For Push-to-Lock forks only - route the cable housing from the remote lever, around the rear of the crown, to the fork topcap cable stop and cut to length. Install a ferrule on the remote end.
  3. For Push-to-Unlock forks only – route the cable housing from the remote lever, across the front of the crown, to the fork topcap cable stop and cut to length. Install ferrules on both ends.
  4. Set the remote lever to OPEN mode by pushing the release lever. Make sure that the cable head is completely seated in the remote lever.
  5. For 2-Position remotes only - use a short piece of housing with one ferrule between the in-line barrel adjuster and the remote lever body.
  6. With all cable housing fully seated and no slack in the system, lightly lubricate the inner cable and thread it through the cable housing and around the fork remote pulley.
  7. While holding the cable tight, tighten the pinch bolt, cut off excess cable, and crimp the end.

 

 

GRIP DAMPERS (Push-to-Lock only)

  1. Install the remote lever onto your handlebar. Do not exceed 1.7 Nm (15 in-lb). Less torque may be needed for carbon bars. Refer to the handlebar manufacturer’s instructions for use with carbon bars. Make sure to check for clearance between the remote lever and any brake or shifter controls.
  2. Route the cable housing from the fork topcap, around the rear of the crown, to the remote lever and cut to length. Install a ferrule on the end of the housing at the remote lever. The end of the housing at the fork topcap does not require a ferrule.
  3. For 2-Position remotes only - use a short piece of housing with one ferrule between the in-line barrel adjuster and the remote lever body.
  4. Set the remote lever to FIRM mode by pushing the actuation lever. Make sure that the cable head is completely seated in the remote lever.
  5. Use a 5 mm hex wrench to turn the remote pulley clockwise until you feel it lightly stop, then hold it in place. For forks with the cable exiting the topcap at the rider’s 1 o’clock position: the remote pulley should stop at the 10-11 o’clock position. For forks with the cable exiting the topcap at the rider’s 7 o’clock position:the remote pulley should stop at the 4-5 o’clock position.
  6. With all cable housing fully seated and no slack in the system, lightly lubricate the inner cable and thread it through the cable housing and around the fork remote pulley. While gently holding the remote pulley against the clockwise stop with your 5 mm hex wrench, tighten the pinch bolt.
  7. Release the 5 mm hex wrench from the remote pulley, cut off the excess inner cable, and crimp the end.
  8. The in-line barrel adjuster may be used to change the lockout blow-off force. Clockwise barrel adjustment increases blow-off force, while counter-clockwise adjustment decreases blow-off force.


Using the 2-Position Remote

The 2-position remote is designed to be used in place of a front shifter, under the handlebar on the rider's left side. The 2-position remote can be used with 2 cables to control both the front fork and rear shock simultaneously.

 

2-pos-remote.jpg

 

The 2-Position Remote lets you to switch between the OPEN and FIRM modes while riding.

  • Push-to-Lock – Push the actuation lever to set the fork to FIRM mode. Push the release lever to set the fork to OPEN mode.
  • Push-to-Unlock – Push the actuation lever to set the fork to OPEN mode. Push the release lever to set the fork to FIRM mode.


Adjusting Fork Compression Ratio with Air Volume Spacers

Adjust Your Compression Ratio For The Perfect Air Spring Feel

Changing volume spacers in the 36 FLOAT fork is an easy internal adjustment that allows you to change the amount of mid stroke and bottom out resistance.

  • If you have set your sag correctly and are using full travel (bottoming out) too easily, then you could install one or more spacers to increase bottom out resistance.

  • If you have set your sag correctly and are not using full travel, then you could remove one or more spacers to decrease bottom out resistance.

 32-34-air-spring-curves.jpg

 

36 FLOAT Volume Spacer Configurations
Travel Volume Spacers Factory Installed *Max Volume Spacers
170 0 5
160 1 6
150 2 7
140 4 8
130 5 9

 

36 FLOAT E-Bike+ Volume Spacer Configurations
Travel Volume Spacers Factory Installed *Max Volume Spacers
160 1 6
150 2 7
140 4 8
130 5 9

 

36 RHYTHM Volume Spacer Configurations
Travel Volume Spacers Factory Installed *Max Volume Spacers
180 1 5
170 1 6
160 2 7
150 3 7
140 4 8
130 5 8

 

38 FLOAT Volume Spacer Configurations
Travel Volume Spacers Factory Installed *Max Volume Spacers
180 1 4
170 2 5
160 3 6
150 4 6

 

38 FLOAT E-Bike+ Volume Spacer Configurations
Travel Volume Spacers Factory Installed *Max Volume Spacers
180 2 4
170 3 5
160 4 6
150 5 6

*DO NOT EXCEED THE MAXIMUM NUMBER OF VOLUME SPACERS LISTED ABOVE!   

 

36mm FLOAT volume spacer PN: 234-04-736 is orange and has a volume of 10cc

36 Rhythm volume spacer PN: 234-44-079 is purple and has a volume of 10cc 

36mm E-Bike+ volume spacer PN: 234-04-953 is green and has a volume of 10cc

38mm FLOAT and E-Bike+ volume spacer PN: 234-44-189 is yellow and has a volume of 10cc

 



WARNING: Never attempt to modify air volume spacers, as this can damage your fork causing a loss of control of the bicycle leading to SERIOUS INJURY or DEATH.

WARNING: FOX suspension products contain pressurized nitrogen, air, oil, or all 3. Suspension misuse can cause property damage, SERIOUS INJURY OR DEATH. DO NOT puncture, incinerate or crush any portion of a FOX suspension product. DO NOT attempt to disassemble any portion of a FOX suspension product, unless expressly instructed to do so by the applicable FOX technical documentation, and then ONLY while strictly adhering to all FOX instructions and warnings in that instance.

WARNING: Modification, improper service, or use of aftermarket replacement parts with FOX forks and shocks may cause the product to malfunction, resulting in SERIOUS INJURY OR DEATH. DO NOT modify any part of a fork or shock, including the fork brace (lower leg cross brace), crown, steerer, upper and lower leg tubes, or internal parts, except as instructed herein. Any unauthorized modification may void the warranty, and may cause failure or the fork or shock, resulting in SERIOUS INJURY OR DEATH.

Using the Air Release Buttons

Make sure that your fork is running with the lowest friction possible

 IMG_3645.jpg

 

The Air Release Button at the rear of each fork leg allows the rider to equilize the air pressure between the inside of the fork lower leg and the atmosphere. This can be especially helpful at higher altitudes where the internal/external pressure differential can be its greatest. 

  • Make sure your fork is in an upright position and the exterior is clean of any dirt/debris.
  • Always cover the Air Release Buttons with a rag before pressing to prevent any oil spray.
  • Make sure to hold the buttons down for at least 5-10 seconds to allow for all air to be released.


Service Intervals

Make sure to properly maintain your fork

To best maintain the performance and durability of your product under normal use, FOX recommends that you have regular fork and shock maintenance performed according to the service intervals listed below.

2015 fork service intervals.jpg

 

*For those who ride lift-accessed DH, Park, or Extreme Freeride or in extremely wet/muddy or dry/dusty environmental conditions where trail debris is sprayed onto the fork or shock while on the trail, FOX encourages riders to perform maintenance earlier than recommended above as needed. If you hear, see, or feel something unusual, stop riding immediately and contact a FOX Authorized Service Center for proper servicing.



WARNING: FOX products should be serviced by a qualified bicycle service technician, in accordance with FOX specifications. If you have any doubt whether or not you can properly service your FOX product, then DO NOT attempt it. Improperly serviced products can fail, causing the rider to lose control resulting in SERIOUS INJURY OR DEATH. 


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