Servicing Your Tune Shock SK18 Rear Shock: Tools and Tips

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The Tune Shock SK18 [paid link] from Trunnion is a high-performance rear shock known for its precision, durability, and exceptional damping capabilities. Whether you’re maintaining an existing shock or troubleshooting setup issues, understanding the service process is crucial to ensure the optimal performance of your bike. In this guide, we will walk you through the necessary tools, installation and maintenance procedures, troubleshooting tips, and customization strategies for the Tune Shock SK18 [paid link].

Tools Required

Before starting any work on your Tune Shock SK18 rear shock, make sure you have the following tools:

  • Shock pump
  • Torque wrench [paid link] (with appropriate range)
  • 10mm and 5mm hex wrenches
  • 3mm Allen key
  • Teflon grease
  • Rags for cleaning
  • Isopropyl alcohol for cleaning
  • Small adjustable spanner
  • Rear shock eyelet tool
  • Needle and syringe (for damper oil refilling)

Installing the Tune Shock SK18

Installing the Tune Shock SK18 rear shock is a straightforward process, but it requires precise steps to avoid improper setup. Follow these instructions carefully to ensure correct installation:

  1. Prepare the frame: Clean the shock mounting points on the bike frame to remove any debris, dirt, or old grease. This ensures a smooth fit for the rear shock.
  2. Check shock compatibility: Confirm that the shock’s eyelet dimensions match the bike frame. The SK18 is designed to fit a specific range of bike frame setups, so ensure compatibility before proceeding.
  3. Mount the shock: Slide the upper and lower shock eyelets into their respective mounts on the frame. Use the correct bolts and washers. Tighten them using a 5mm hex wrench. Ensure not to overtighten, as this can damage the shock or frame.
  4. Set the air pressure: Use a shock pump to set the air pressure according to your rider weight and the desired sag. Refer to the manufacturer’s guidelines for recommended pressure levels.
  5. Torque the bolts: Use a torque wrench [paid link] to tighten the bolts to the recommended torque settings (typically 10-15 Nm). Incorrect torque can cause the shock to loosen or shift during use.

Once installed, the shock should be secure, with no play in the mounting points. Perform a final inspection to make sure everything is properly aligned.

Maintenance of the Tune Shock SK18

Regular maintenance is essential to keep your Tune Shock SK18 performing optimally. Here are the key steps for maintaining the shock over time:

Cleaning the Shock

  1. Wipe down the shock: After each ride, use a rag to wipe off any dirt or debris from the shock body. This helps prevent any grime from building up, which could cause internal damage over time.
  2. Check seals: Inspect the seals for any signs of wear or damage. If there is any visible wear, it’s time to replace them to prevent air and oil leakage.

Oil Change

An oil change is necessary to keep the damper working efficiently. Follow these steps for an oil change:

  1. Remove the shock from the bike: Follow the installation steps in reverse to carefully remove the shock from the frame.
  2. Drain the old oil: Use a needle and syringe to remove any remaining damper oil from the shock.
  3. Refill with fresh oil: Refill the damper with the manufacturer-recommended oil. Be sure to use the right type and amount of oil to maintain optimal shock performance.
  4. Reassemble and reattach: Once the oil change is complete, reassemble the shock and reinstall it on the bike.

Air Can Service

The air canister should be serviced regularly to ensure smooth operation:

  1. Remove the air can: Using the rear shock eyelet tool, carefully remove the air can from the shock body.
  2. Lubricate and inspect the seals: Clean the internal components and apply a small amount of Teflon grease to the seals before reassembling the air can. This ensures proper movement and reduces wear.
  3. Reinstall the air can: Once the air can is properly lubricated and sealed, reattach it to the shock body.

Troubleshooting Common Set-Up Issues

While the Tune Shock SK18 is a highly reliable shock, issues can arise over time, especially if the shock is not properly set up. Here are some common problems and how to troubleshoot them:

1. Shock Not Holding Air Pressure

  • Cause: This can be due to a damaged seal or a problem with the valve.
  • Solution: Inspect the shock’s valve for any damage or leaks. If the valve appears intact, check the seals. Replace any worn or damaged seals. Afterward, perform an air pressure check with a shock pump.

2. Excessive Sag

  • Cause: Too little air pressure can lead to excessive sag.
  • Solution: Reinflate the shock to the correct pressure using a shock pump. Ensure the pressure matches your rider weight and preferred suspension setup.

3. Too Much Rebound

  • Cause: Incorrect rebound damping settings can lead to excessive rebound.
  • Solution: Adjust the rebound dial to a slower setting to reduce the rebound speed. Experiment with small adjustments until the ride feels balanced.

4. Noisy Shock

  • Cause: A noisy shock could be due to dirt or debris in the shock body or insufficient lubrication.
  • Solution: Clean the shock thoroughly and lubricate the seals and moving parts as needed.

Customization and Optimization for Better Performance

One of the most significant advantages of the Tune Shock SK18 is its tunable nature. To optimize your rear shock for your riding style and terrain, consider these customization options:

Adjusting the Rebound and Compression Damping

  • Rebound Damping: Adjust the rebound settings to control how quickly the shock returns after compression. For fast terrain or downhill riding, a slower rebound is beneficial. For smoother rides, faster rebound settings may be preferred.
  • Compression Damping: If you find the shock too soft or too harsh, adjust the compression settings to either firm it up or allow for more plushness, depending on your riding needs.

Fine-tuning Air Pressure

The air pressure in the Tune Shock SK18 plays a significant role in achieving the right level of suspension feel. Adjust the pressure to fine-tune your ride:

  • Less Air Pressure: Softer, more plush ride for smoother trails or absorbing impacts.
  • More Air Pressure: Firmer ride for technical terrain or reducing bottom-out during big hits.

Comparison with Similar Models

When comparing the Tune Shock SK18 with other rear shocks in the same category, it is important to focus on key performance attributes such as travel range, adjustability, and weight.

Compared to the Fox Float DPX2

  • Adjustability: The Tune Shock SK18 offers more precise rebound and compression tuning compared to the Fox Float DPX2, making it ideal for riders looking for fine-tuned performance.
  • Weight: The Tune Shock SK18 is slightly lighter than the Fox Float DPX2, which is a critical factor for riders looking to minimize bike weight.
  • Price: The Tune Shock SK18 is priced competitively, offering great value for riders who want high-end performance at a lower cost than some other premium models.

Compared to the RockShox Monarch Plus RC3

  • Performance: The Tune Shock SK18 provides smoother performance at lower pressures, while the RockShox Monarch Plus RC3 [paid link] is better suited for riders who prefer a firmer setup.
  • Adjustments: Both models offer a good range of adjustments, but the Tune Shock SK18’s fine-tuning options make it stand out for those who seek detailed control over their ride.

Compatibility with Other Drivetrain Components

The Tune Shock SK18 is designed to be compatible with most modern mountain bike frames that feature a trunnion mount. However, there are some considerations to keep in mind:

  • Frame Mounting: Ensure that the shock’s mounting hardware matches the frame’s dimensions.
  • Other Components: The shock works seamlessly with most drivetrain setups, but if you have a specific preference for rear shock compatibility with components like linkage designs or pivot systems, always consult your bike frame’s manufacturer for detailed compatibility information.

By understanding the specifics of your Tune Shock SK18, its proper maintenance, troubleshooting tips, and customization options, you can keep your rear shock performing at its best. Regular servicing and adjustments will maximize its lifespan and ensure that your bike is ready for any trail.