The Float 40 Factory eMTB from Fox is a top-tier downhill suspension fork tailored for aggressive electric mountain biking. With its robust chassis, advanced damping systems, and fine-tuned adjustability, it is engineered to deliver exceptional control and confidence under extreme riding conditions. This guide covers the installation, adjustment, maintenance, and optimization of the Float 40 Factory eMTB fork, along with troubleshooting, customization, and compatibility insights.

Tools Required

• Torque wrench [paid link] with Allen bits (4mm, 5mm, 6mm)
• Suspension pump
• Crown race setting tool
• Fork cutting guide and saw (if cutting steerer tube)
• Star nut setter or compression plug (for carbon steerers)
• Grease and anti-seize compound
• Clean rags and isopropyl alcohol

Installation of the Float 40 Factory eMTB Fork

Installing the Float 40 Factory eMTB requires careful preparation to ensure correct integration with your bike frame and cockpit components. Begin by verifying steerer tube length. Measure the required steerer tube height based on your head tube, headset stack, and stem height. If cutting is necessary, ensure a precise cut using a fork cutting guide. Install the crown race using a race setting tool, ensuring it sits flush with the fork crown.

Next, grease the steerer tube lightly before inserting it into the head tube. Slide on the headset spacers and stem. Use a torque wrench [paid link] to secure the stem bolts evenly. Depending on your frame material, use a star nut or compression plug. Align the fork and handlebar, tighten headset preload, and confirm there’s no play in the headset by rocking the bike back and forth with the front brake engaged.

Suspension Adjustment Settings

The Float 40 Factory eMTB fork offers a wide range of adjustability to dial in the suspension to your weight, terrain, and riding style.

Air Spring Setup
Start by setting the air pressure based on your rider weight, referencing the Fox user chart. Use a suspension pump to adjust PSI. Set sag to approximately 20–25% for enduro-style riding and 15–20% for downhill. Measure sag by sitting on the bike in full gear and using the rubber o-ring on the fork stanchion.

High and Low-Speed Compression
The fork features independent high-speed and low-speed compression adjusters. Turn the blue low-speed knob for pedaling support and small bump compliance. The gold high-speed knob controls big hit performance—fine-tune for drops and aggressive trail sections.

Rebound Tuning
Located at the bottom of the right leg, the red knob controls rebound. Start at the midpoint and adjust in single-click increments. Slower rebound improves control in rough terrain, while faster rebound is better for flowy trails.

Routine Maintenance Practices

Regular maintenance ensures consistent performance and extends the lifespan of the fork.

Every 30 Hours of Riding:
Clean the stanchions and wipers after each ride using a soft cloth and isopropyl alcohol. Check air pressure and rebound settings. Inspect for oil seepage or contamination.

Every 50 Hours of Riding:
Perform a lower leg service. Remove the fork lowers, clean internals, and replace bath oil with the specified volume and weight. Inspect foam rings and wipers; replace if worn.

Every 100–200 Hours or Annually:
Conduct a full damper and air spring service. This includes replacing seals, damper fluid, and inspecting internal wear. Fox recommends this be performed by a certified technician for best results.

Troubleshooting Common Setup Issues

Excessive Fork Dive:
Check if sag exceeds 30%. Increase air pressure or add volume spacers for more mid-stroke support.

Harsh Bottom-Outs:
Adjust high-speed compression or add tokens to increase ramp-up. Ensure damper oil levels are correct.

Sticky Travel or Inconsistent Rebound:
Check for dirty or dry seals. Perform a lower leg service and inspect rebound adjuster for debris or damage.

Creaking from Crown or Steerer:
Verify headset torque and steerer tube cut. Apply carbon paste or grease as appropriate to eliminate micro-movement.

Customization and Optimization for Trail Performance

The Float 40 Factory eMTB can be fine-tuned for terrain-specific riding and rider preference.

Volume Spacer Tuning:
Adjust progressiveness by adding or removing volume spacers inside the air chamber. More spacers increase bottom-out resistance; fewer provide a more linear feel.

Axle Spacing and Axle-to-Crown Height:
The 40mm stanchion chassis offers optimal stiffness. Riders can use 20mm thru-axles for maximum steering precision. Adjust headset spacers and bar rise to match axle-to-crown height and maintain geometry.

Chassis Protection:
Install fork bumpers and frame protectors to shield the fork crown and down tube during full compression impacts.

Damper Cartridge Upgrades:
Consider upgrading to the latest Grip2 damper version if not already installed. It provides better tunability and damping sensitivity.

Compatibility with Drivetrain and Frame Components

The Float 40 Factory eMTB is designed for long-travel, dual-crown compatibility and integrates seamlessly with most downhill and eMTB frames. However, consider the following compatibility notes:

• Steerer Type: Tapered steerer tube; ensure your headset matches.
• Brake Mounts: Uses 203mm post-mount; compatible with 203mm or larger rotors.
• Wheel Size: Optimized for 27.5″ and 29″ wheels depending on fork variant.
• Tire Clearance: Up to 2.6″ width without fender interference.
• Frame Compatibility: Ensure head tube and downtube clearance for dual crown forks.

Comparison with Similar Fork Models

Compared to the Fox 38 Factory, the Float 40 Factory offers significantly more stiffness and adjustability for downhill-specific applications. The 38 is ideal for aggressive trail and enduro riding but lacks the robust dual-crown architecture of the Float 40, which provides unmatched tracking through rock gardens and drops.

Versus the RockShox Boxxer Ultimate, the Float 40 Factory offers more nuanced damping adjustment with the Grip2 damper and superior small bump compliance. The Boxxer may have a slight weight advantage, but the Fox excels in sensitivity and tuning options.

Frequently Asked Questions

Is the Float 40 Factory eMTB compatible with trail bikes?
No, it is intended for downhill and heavy-duty eMTB use. It requires a frame built for dual-crown forks.

Can I use regular Fox 40 volume spacers in the eMTB version?
Yes, the volume spacers are cross-compatible across Float 40 series forks.

What is the maximum tire size I can run?
Tire clearance supports up to 2.6″ wide tires without fender contact.

How often should I service the Grip2 damper?
Fox recommends a full damper service every 100–200 hours of ride time or annually.

What stanchion protection is recommended?
Use custom fork bumpers designed for the Float 40 to avoid contact with the frame during compression.

Is this fork overkill for park riding?
While it’s designed for aggressive downhill, it performs exceptionally in bike parks, especially on heavier eMTBs.

Conclusion

The Float 40 Factory eMTB fork stands as a pinnacle of downhill suspension engineering. With its exceptional chassis rigidity, fine-tuned damping options, and robust construction, it elevates your trail experience to a professional level. When installed and maintained correctly, it delivers unparalleled traction, confidence, and control—essential for the demanding terrain that modern eMTBs are built to conquer.