FORK- 2021 36mm/38mm | Bike Help Center | FOX (2024)

FOX / Help Center / Bike / FORK- 2021 36mm/38mm

Sections

  • Before You Ride
  • Mounting Disc Brakes
  • Installing the Front Wheel (15mm or 20mm Pinch Axle)
  • Setting Fork Air Pressure
  • Adjusting Rebound
  • Factory and Performance Elite FIT4 Compression Adjusters
  • Factory and Performance-Elite Series GRIP2 Compression Adjusters
  • Performance Elite LSC Compression Adjuster
  • Adjusting GRIP Compression Damping
  • Remote Installation
  • Using the 2-Position Remote
  • Adjusting Fork Compression Ratio with Air Volume Spacers
  • Using the Air Release Buttons
  • Service Intervals

For general information and installation instructions clickhere »

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.


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 inSERIOUS 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.

2021 Rhythm forks also use 180mm Post Mounts that allow you to bolt your caliper directly to the fork and utilize a 180mm rotor.Maximum rotor size for Rhythm forks is 205mm.

FORK- 2021 36mm/38mm | Bike Help Center | FOX (1)


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.

FORK- 2021 36mm/38mm | Bike Help Center | FOX (2)

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.

FORK- 2021 36mm/38mm | Bike Help Center | FOX (3)



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 70-75ËšF. Normal operating temperature range for FOX products is 20-140ËšF.

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 FOXsuspension, adjust the air pressure to attain your propersag setting. Sag is the amount your suspension compressesunder your weight and riding gear. Sag range should be setto 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.FORK- 2021 36mm/38mm | Bike Help Center | FOX (4)
  2. Attach a FOX High Pressure Pump to the Schrader valve.
  3. Pump your fork to the appropriate pressure as listedin the 'Suggested starting points for setting sag' table below, then remove the pump.
  4. Usingyour forkssag setting o-ring onthe leftupper tube (ortemporarily install a zip tie tothe upper tube), slide the o-ring (or zip tie) down against thefork dust wiper.
  5. Make sure that your compression adjusters are in the Open position
    • Rotatethe compression leverto 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. Assumeyour 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 pressureuntil 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 capon clockwise until snug.
Suggested Sag Measurements
Travel15% sag (Firm)20% sag (Plush)
130mm/ 5.1 in20mm/ 0.8 in26mm/ 1.0 in
140mm/ 5.5 in21mm/ 0.8 in28mm/ 1.1 in
150mm/ 5.9 in23mm/ 0.9 in30mm/ 1.2 in
160mm/ 6.3 in24mm/ 0.9in32mm/ 1.3 in
170mm/ 6.7 in25mm/ 1.0 in34mm/ 1.3 in
180mm/ 7.1 in27mm/ 1.1 in36mm/ 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)
120-13054-59667155
130-14059-64707659
140-15064-68748163
150-16068-73788567
160-17073-77829072
170-18077-82869576
180-19082-86899980
190-20086-919410485
200-21091-959910989
210-22095-10010511393
220-230100-10410911597
230-240104-109113117102
240-250109-113117120106
Suggested Starting Points For Setting Sag 38mm
Rider Weight (lbs)Rider Weight (kgs)FLOAT and E-Bike+ Pressure (psi)
120-13054-5972
130-14059-6476
140-15064-6880
150-16068-7384
160-17073-7789
170-18077-8293
180-19082-8697
190-20086-91102
200-21091-95106
210-22095-100110
220-230100-104114
230-240104-109119
240-250109-113123


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.

FORK- 2021 36mm/38mm | Bike Help Center | FOX (5)

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

Rider Weight (lbs)Rider Weight (kgs)36/38 FIT436/38 GRIP36/38 GRIP2
LSRHSR
120-13054-59141398
130-14059-64131287
140-15064-68121176
150-16068-73111076
160-17073-779965
170-18077-828865
180-19082-867754
190-20086-916643
200-21091-955543
210-22095-1004432
220-230100-1043321
230-240104-1092221
240-250109-1131110

FORK- 2021 36mm/38mm | Bike Help Center | FOX (6)

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.



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

3-Position Lever: The 3-position lever is useful tomake on-the-fly adjustments tocontrol shock performance undersignificant changes in terrain, andis intended to be adjustedthroughout the ride. You can use the OPEN mode duringrough descending, the MEDIUMmode for undulating terrain, andthe FIRM mode forsmooth climbing.

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

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*OPEN Mode Adjust: Open mode adjust is useful tocontrol fork performance underrider weight shifts, G-outs, andslow inputs.OPEN mode adjust provides 22additional fine tuning adjustmentsfor the OPEN mode.Setting 22 will have a more plushfeel and setting 1 will have afirmer feel.

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

FORK- 2021 36mm/38mm | Bike Help Center | FOX (8)

FORK- 2021 36mm/38mm | Bike Help Center | FOX (9)

*Factory and PerformanceElite Series forks only.



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 forkperformance during bigger hits,landings, and square-edged bumps.

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Low-speed compression adjustmentis useful to control fork performanceduring rider weight shifts, G-outs,and other slow inputs.

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FOX recommends turning adjusters fully clockwise until they come to agentle 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 theHigh-speed compression set 5 clicks out(counter-clockwise) andLow-speed compression set 10clicks out(counter-clockwise) from closed (full clockwise).

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Adjusting yourlow-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)adjustmentis useful to control fork performanceduring rider weight shifts, G-outs,and other slow inputs.

FORK- 2021 36mm/38mm | Bike Help Center | FOX (13)



3-Position Micro Adjust:The3-position lever is useful tomake on-the-fly adjustments tocontrol fork performance undersignificant changes in terrain, andis intended to be adjustedthroughout 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.

FORK- 2021 36mm/38mm | Bike Help Center | FOX (14)



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.


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.

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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.


Adjust Your Compression Ratio For The Perfect Air Spring Feel

Changing volume spacers in the 36 FLOAT fork is an easy internal adjustment thatallows 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 couldremove one or more spacers to decrease bottom out resistance.

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36 FLOAT Volume Spacer Configurations
TravelVolume Spacers Factory Installed*Max Volume Spacers
17005
16016
15027
14048
13059
36 FLOAT E-Bike+ Volume Spacer Configurations
TravelVolume Spacers Factory Installed*Max Volume Spacers
16036
15047
14048
13059
36 RHYTHM Volume Spacer Configurations
TravelVolume Spacers Factory Installed*Max Volume Spacers
18015
17016
16027
15037
14048
13058
38 FLOAT Volume Spacer Configurations
TravelVolume Spacers Factory Installed*Max Volume Spacers
18014
17025
16036
15046
38 FLOAT E-Bike+ Volume Spacer Configurations
TravelVolume Spacers Factory Installed*Max Volume Spacers
18024
17035
16046
15056

*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.

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

FORK- 2021 36mm/38mm | Bike Help Center | FOX (17)

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.


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.

FORK- 2021 36mm/38mm | Bike Help Center | FOX (18)

*Suspension product will require more frequent servicing the harder they are worked.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, or e-mtb's, 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.


FORK- 2021 36mm/38mm | Bike Help Center | FOX (2024)
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