Rebuilding the Fenix AIR [paid link] rear shock from Fast Suspension can improve your bike’s performance and extend the lifespan of the shock. The Fenix AIR [paid link] is a high-performance rear shock, designed to provide smooth, responsive suspension on rugged [paid link] trails. Rebuilding this shock at home can save you time and money while ensuring your bike stays in top condition. This guide will take you through the process step by step, covering all the essential aspects, from disassembly and cleaning to reassembly and testing.
Tools Required
Before beginning the rebuild, gather the following tools and components:
- Torque wrench [paid link]
- 5mm and 8mm Allen wrenches [paid link]
- Shock pump
- Small flathead screwdriver
- Cleaning brushes
- Shock oil (specific to Fenix AIR model)
- Oil seals and bushings (if replacing)
- Pliers
- Replacement air can seal (optional)
- Grease (for bushing lubrication)
- Rebuild kit for Fenix AIR (recommended)
Disassembly of the Fenix AIR Rear Shock
Step 1: Remove the Shock from the Bike
Start by removing the rear shock from the bike frame. Use a 5mm Allen wrench [paid link] to unscrew the bolts securing the shock to the frame. Be careful not to damage any other components or the shock itself. Once removed, place the shock on a clean surface, ensuring it is not exposed to dirt or contaminants.
Step 2: Prepare for Disassembly
Before disassembling the shock, ensure you are working in a clean, organized space. Lay down a clean cloth or mat to catch any small parts and keep your workspace tidy. This will make it easier to track components as you disassemble.
Step 3: Remove the Air Can
To access the internal components of the Fenix AIR rear shock, you will first need to remove the air can. Locate the air valve and use the correct size Allen wrench [paid link] to remove the air can from the shock body. This step requires careful handling to prevent damaging the seals or damaging the air chamber.
After removing the air can, you will expose the internal components such as the damper shaft and seals.
Cleaning and Inspection
Step 4: Clean the Shock Components
With the shock disassembled, thoroughly clean all parts. Use a small flathead screwdriver to remove any dirt, grime, or old grease from the shock body. A soft cleaning brush can be useful for getting into hard-to-reach areas. Pay special attention to the shock seals, as they play a critical role in keeping dirt and debris out of the internal components.
Once cleaned, inspect the shock for any wear or damage. Check the seals, air can, and shock body for any signs of wear. If the seals or bushings appear worn or damaged, replace them with new parts from the rebuild kit.
Step 5: Inspect the Air Can and Seals
Check the air can and its seals for any wear. If the air can seal appears worn or damaged, now is the time to replace it. Over time, these seals can degrade, leading to air leaks and poor shock performance. Carefully install a new seal if necessary, ensuring it fits snugly.
Rebuilding the Shock
Step 6: Reassemble the Damper Cartridge
With the air can removed and all parts cleaned, the next step is to address the damper cartridge. Ensure the damper shaft is free of dirt and any old oil. If you’re replacing the oil in the shock, drain out the old oil and refill the damper with the recommended oil for the Fenix AIR model.
Carefully reassemble the damper cartridge, ensuring it is aligned properly. Use a torque wrench [paid link] to tighten the parts to the manufacturer’s specifications. This will ensure the shock performs optimally without leaks or internal damage.
Step 7: Install New Seals and Bushings
If necessary, replace the seals and bushings. Carefully lubricate the bushings and seals with grease before installing them. This ensures smooth movement and protects the seals from wear. Install each component carefully, making sure not to damage any internal parts.
Step 8: Reinstall the Air Can
Once the damper and seals are reassembled, it’s time to reinstall the air can. Ensure that the air can is aligned correctly with the shock body. Slowly and carefully slide the air can over the damper, making sure it fits securely.
Use your torque wrench to tighten the air can bolts according to the recommended torque settings. This ensures a secure seal and prevents leaks.
Inflation and Testing
Step 9: Inflate the Shock
Once the shock is reassembled, use a shock pump to inflate the shock to the recommended pressure. Check the shock’s pressure with a pressure gauge to ensure you have the correct setting for your weight and riding style. Refer to the manufacturer’s specifications for the ideal pressure range.
Step 10: Test the Shock
With the shock inflated, reattach it to the bike frame using the appropriate hardware. Ensure all bolts are tightened to the correct torque setting. Once installed, test the shock for proper functioning. Press down on the seat or rear triangle to check for smooth compression and rebound. If the shock feels too soft or too stiff, adjust the air pressure accordingly.
Troubleshooting Common Issues
Issue 1: Shock Loses Air Pressure
If your Fenix AIR rear shock loses air pressure quickly, it may be due to a worn air can seal or damaged internal components. In this case, replace the seals and inspect the internal parts for damage. Rebuild kits are available from Fast Suspension to replace worn components.
Issue 2: Poor Compression or Rebound Performance
If the shock is not performing as expected, such as poor compression or rebound, it could be due to old or insufficient shock oil. Make sure the damper is properly filled with the correct oil and that the air can is correctly sealed.
Issue 3: Excessive Noise from the Shock
Excessive noise, such as knocking or squeaking, can be caused by dry bushings or seals. Make sure all parts are properly lubricated before reassembling the shock. If the noise persists, inspect the shock body for cracks or damage that could be causing the issue.
Customization and Optimization
Adjusting Air Pressure for Better Performance
One of the easiest ways to optimize the performance of your Fenix AIR rear shock is by adjusting the air pressure. The air pressure directly affects the shock’s compression and rebound characteristics. For better support on technical trails, slightly increasing the air pressure can offer more responsive performance. For smoother rides on less demanding trails, reducing the air pressure can improve comfort.
Fine-Tuning Compression and Rebound Damping
The Fenix AIR rear shock offers adjustment knobs for compression and rebound damping. Fine-tuning these settings allows you to tailor the shock’s behavior to different riding conditions. Start with the manufacturer’s baseline settings and make small adjustments based on your personal preference.
Compatibility with Other Drivetrain Components
When rebuilding or replacing the Fenix AIR rear shock, it’s important to consider its compatibility with other drivetrain components, such as the rear derailleur and cassette. The rear shock’s performance can influence the overall handling and ride quality, so ensure your shock settings match the rest of your bike’s suspension and drivetrain.
If you’re running a specific drivetrain configuration, such as a 1×11 or 1×12 system, consider your bike’s overall geometry and how the shock’s performance will complement your setup. A well-maintained rear shock like the Fenix AIR can help maintain optimal performance and efficiency when paired with the right drivetrain components.
Conclusion
Rebuilding the Fenix AIR rear shock at home requires careful attention to detail and the right tools, but it’s a manageable task for anyone with the necessary skills. By following the steps outlined above, you can ensure that your shock is properly serviced and reassembled, ready for optimal performance on the trail. Regular maintenance and timely rebuilding will keep your Fenix AIR rear shock performing at its best, giving you a smoother, more controlled ride every time you hit the trails.