DIY Rear Shock Sag Setup for Deluxe Ultimate RCT

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When it comes to mountain biking, achieving the perfect suspension setup can make a significant difference in your riding experience. The RockShox Deluxe Ultimate RCT rear shock is an excellent choice for riders looking to improve both performance and comfort. Proper sag setup is crucial to maximizing your bike’s suspension and ensuring optimal performance on various trails. In this guide, we’ll walk you through the process of setting up the sag for your RockShox Deluxe Ultimate RCT rear shock, as well as provide tips for troubleshooting and fine-tuning your suspension.

Understanding Rear Shock Sag

Sag refers to the amount the rear shock compresses under the rider’s weight. Getting the correct sag is essential because it ensures that the suspension works effectively, providing comfort and control while preventing bottoming out or excessive travel. The correct sag setting depends on factors such as your weight, riding style, and the terrain you’re riding on. A properly set sag allows the suspension to stay active and responsive, especially over rough terrain, without sacrificing stability.

Tools Required

  • Shock pump
  • Ruler or measuring tape
  • Marker or tape for measurement reference
  • Bathroom scale (optional)

Preparing the Bike for Setup

Before setting up the sag, ensure that your bike is in a stable position. This will help avoid errors in measurements during the setup process.

  1. Place the bike on a flat surface: Ensure the bike is standing upright, preferably using a bike stand [paid link]. If you don’t have a stand, it’s possible to do this with the bike lying on the ground, though a stand will make the process easier.
  2. Check the air pressure in the shock: Ensure that your RockShox Deluxe Ultimate RCT is fully inflated before measuring sag. If you are unsure of the current air pressure, you can check the recommended pressure range provided by RockShox or consult the manual for your specific riding weight.
  3. Get the rider’s weight: The correct air pressure is largely determined by the rider’s weight. If you don’t have an exact weight measurement, you can use a bathroom scale for an approximate reading.

Setting Up the Sag

  1. Set the initial air pressure: Start by adjusting the air pressure to the recommended baseline according to your weight. You can find the recommended pressure range for your specific weight category on the shock’s sticker or RockShox’s website. Use a shock pump to inflate the shock to this initial pressure.
  2. Use a zip tie or marker to mark the shock stanchion: This will help you measure the amount of sag accurately. Place the zip tie or a piece of tape on the stanchion of the shock. The mark should be at the top of the shock body when the shock is in its fully extended position (no rider weight applied).
  3. Sit on the bike in your riding position: Once you are comfortably seated on the bike, let the suspension compress under your weight. Keep your riding posture as natural as possible, with your hands on the handlebars and feet on the pedals. Allow the shock to settle in its natural position.
  4. Measure the sag: After settling in, dismount and measure the distance the shock has compressed. The distance between the mark on the stanchion and the original position gives the amount of sag.
    • For optimal performance, the general rule for sag is between 25-30% of the shock’s total travel. For example, if your rear shock has 150mm of total travel, you should aim for around 37.5mm to 45mm of sag.
  5. Adjust the air pressure: If the sag is too high (i.e., more than 30%), increase the air pressure in the shock to reduce the sag. Conversely, if the sag is too low (i.e., less than 25%), decrease the air pressure to allow for more compression.
  6. Recheck sag and adjust as necessary: After adjusting the air pressure, repeat the sag measurement process until you reach the desired sag percentage. It may take a few attempts to dial it in perfectly.

Troubleshooting Common Set-Up Issues

  1. Excessive Sag (Too Soft)
    • Symptoms: The bike feels overly plush, and the suspension bottoms out too easily on rough terrain.
    • Solution: Increase the air pressure in the shock to reduce the sag. If increasing air pressure doesn’t help, check the shock’s rebound settings as well, as they can sometimes cause excessive compression if set too fast.
  2. Insufficient Sag (Too Stiff)
    • Symptoms: The bike feels too harsh, and you’re not getting enough travel from the suspension. The rear end feels unresponsive.
    • Solution: Decrease the air pressure to allow more sag. If necessary, check the shock’s damping settings, as too much low-speed compression damping can prevent the shock from sagging correctly.
  3. Sag Settings Change Over Time
    • Symptoms: The suspension feels different after some riding, or the sag changes.
    • Solution: This can happen due to air pressure loss over time. Always check the air pressure in your shock regularly, especially before rides, and adjust as needed.

Customizing and Optimizing Performance

To get the most out of your RockShox Deluxe Ultimate RCT, you’ll want to fine-tune not just the sag but also other settings such as rebound and compression damping.

  1. Rebound Settings: Adjust the rebound to control how quickly the shock returns after compression. If the shock returns too quickly, it can cause instability. If it’s too slow, it may feel sluggish. A good starting point is to set the rebound to a medium setting and adjust based on your riding style and terrain.
  2. Compression Damping: Compression damping controls how the shock responds to compressive forces. For trail riding, a moderate setting works well, while downhill riders may prefer firmer compression damping to prevent bottoming out. Experiment with small adjustments until you achieve the ideal balance between comfort and control.
  3. Volume Spacers: The Deluxe Ultimate RCT features adjustable volume spacers, which allow you to modify the shock’s progression. Adding spacers will make the shock feel firmer at the end of the travel, while removing them will provide a more linear feel throughout the stroke.

Compatibility with Other Drivetrain Components

The RockShox Deluxe Ultimate RCT is designed to work with most modern mountain bike frames and drivetrains. However, it’s essential to ensure that your shock’s specifications, including the eye-to-eye length and stroke, match the geometry of your frame. For optimal performance, make sure your rear shock complements your other components, such as the front fork, drivetrain, and wheels.

Many bike brands and models provide specific rear shock recommendations, and RockShox offers different mounting options to accommodate various bike frames. Double-check that the shock is compatible with your frame’s suspension design and travel needs before installation.

Conclusion

Setting up the sag for your RockShox Deluxe Ultimate RCT rear shock is an essential step in optimizing your bike’s performance. With the right sag setup, your suspension will work more efficiently, providing a smoother ride and better control over rough terrain. By following the steps outlined in this guide, you can achieve the perfect sag setup and continue fine-tuning your bike for maximum performance. Remember, each rider’s setup may differ slightly based on personal preferences, so don’t hesitate to make adjustments to suit your riding style and the terrain you frequent.