The Fox 38 Rhythm is a heavy-hitting trail and enduro suspension fork known for its sturdy construction and reliable damping characteristics. While it lacks some of the adjustability features of higher-tier Fox models like the Factory or Performance Elite, the 38 Rhythm still offers a robust platform for riders seeking performance without the premium price tag. This guide details how to properly install, adjust, and maintain your Fox 38 Rhythm fork, along with troubleshooting tips, performance optimization, and compatibility insights.
Tools Required
- 6mm and 5mm Allen keys [paid link]
- Torque wrench [paid link] with Nm settings
- Suspension pump (for air spring adjustments)
- Clean rag and isopropyl alcohol
- Suspension grease and light lubricant
- Cassette tool and wrench (for lower leg service)
- Fox 5-weight Teflon suspension fluid (for maintenance)
Installation of the Fox 38 Rhythm Fork
Installing the Fox 38 Rhythm begins with a proper headset fit and precise torque settings. The steerer tube should be cut to match your frame and stem stack height. Once measured, use a pipe cutter to trim the steerer tube, then install the star nut or insert the threaded insert (for carbon steerers, use a specific insert). Grease the crown race seat and press the crown race securely.
Insert the fork into the head tube, stack your spacers and stem, then torque the stem bolts to 5 Nm and the top cap to preload the headset bearings without binding. Check for smooth steering and no play.
Mount the front wheel, torque the axle to 18-20 Nm, and align the brake caliper. Use the centering method by tightening the caliper bolts while the brake lever is pulled. Ensure the rotor spins without rubbing.
Initial Setup and Air Spring Adjustment
The Fox 38 Rhythm uses an EVOL (extra volume) air spring system. Rider weight, riding style, and terrain influence the air pressure setting. Fox provides a baseline chart, but fine-tuning is key.
Start by setting the air pressure to match your weight. Use a shock pump, not a standard air pump. Add or release pressure until you achieve 25-30% sag—this can be measured by marking the stanchion at full extension and then sitting on the bike in riding gear.
The fork has a self-equalizing negative spring, so make sure to cycle it through its travel after setting the pressure. For aggressive riding or steep terrain, increase pressure slightly for better mid-stroke support.
Rebound and Compression Adjustment
The 38 Rhythm includes a GRIP damper with external rebound and low-speed compression dials.
- Rebound is controlled at the bottom of the right fork leg. Start in the middle of the range and adjust by turning the knob clockwise for slower rebound or counterclockwise for faster return. A properly set rebound prevents packing on repetitive hits and maintains traction.
- Compression is located at the top of the right leg. Turn clockwise to increase compression damping, which firms up the fork feel. Set it based on rider preference and terrain—more open for rough, chattery trails; firmer for smoother trails or climbing.
Routine Maintenance and Lubrication
To keep the 38 Rhythm performing optimally, routine maintenance is essential. Wipe down the stanchions after every ride to remove dirt. Lubricate the foam rings under the dust wipers every 20 hours of riding.
A lower leg service should be done every 50 hours. Remove the lowers using a 5mm Allen, drain the old oil, clean internals with isopropyl alcohol, and replace with 10cc of 5-weight Teflon fluid in each leg. Reinstall the lowers and torque bolts to 7 Nm.
Annually, a full damper and air spring service is recommended. Use only Fox-approved tools and fluids or consult a certified service center.
Troubleshooting Common Setup Issues
1. Excessive Fork Dive:
This often results from too little air pressure or insufficient compression damping. Increase air pressure by 5 psi increments or add clicks to low-speed compression.
2. Harshness on Small Bumps:
Usually due to excessive compression or lack of lubrication. Reduce compression damping slightly and ensure the fork lowers are freshly lubricated.
3. Stiction or Slow Rebound:
Check for dry seals or contamination in the lowers. Perform a lower leg service and clean the stanchions. Adjust rebound to a faster setting if necessary.
4. Clunking Sound:
This could indicate a loose headset or dry bushings. Verify headset preload and inspect the fork’s internals if the noise persists.
Performance Optimization Techniques
Maximize performance by tailoring the setup to your weight and riding style. For aggressive enduro riding, consider using volume spacers in the air spring. The 38 Rhythm allows for token insertion to increase ramp-up at the end of the stroke.
Lowering tire pressures can also balance fork performance. Fine-tune rebound and compression each time you change tire pressure or terrain. Use trail logs to note settings that worked best on different trails.
Customization Options for the 38 Rhythm
Although it lacks high-speed compression adjustability, the 38 Rhythm can be upgraded. Riders can retrofit a GRIP2 damper for independent high- and low-speed adjustments. Custom tuning services are also available from Fox-approved suspension centers.
Swapping the stock sweep adjust knob for a numbered dial can make tuning quicker and more precise. Colored decals and protective fork wraps offer aesthetic customization without affecting performance.
Comparing the Fox 38 Rhythm to Similar Forks
Compared to the Fox 38 Performance Elite, the Rhythm sacrifices adjustability and uses heavier, less machined castings. However, it maintains stiffness and overall chassis integrity.
When lined up against the RockShox ZEB Select, the 38 Rhythm provides a more supportive mid-stroke but lacks the ZEB’s Charger damper sophistication. Price-wise, the Rhythm is an excellent value for aggressive riders who don’t need top-tier tunability.
Compatibility with Other Drivetrain and Brake Systems
The Fox 38 Rhythm uses a standard 15x110mm Boost thru-axle and fits 29” or 27.5” wheels, depending on the model. It supports 180mm to 230mm post-mount disc brakes, with adapters available for larger rotors.
Its steerer is a tapered 1.5” to 1 1/8” format, compatible with most modern frames. Tire clearance is generous, accommodating up to 2.6” tires without interference.
It’s compatible with all common drivetrain systems and can be matched with either 1x or 2x front setups, though most enduro riders will opt for a 1x system.
Final Thoughts
The Fox 38 Rhythm is a performance-focused, entry-level fork within the 38 chassis lineup. With proper setup, regular maintenance, and thoughtful customization, it can deliver high-end trail and enduro performance at a reasonable price point. By following the steps in this guide, riders can optimize suspension responsiveness and ensure long-term durability, unlocking the full potential of the 38 Rhythm.