DIY Rear Shock Sag Setup for Monarch RT3

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Setting up the correct sag for your RockShox Monarch RT3 rear shock is a crucial step to optimize your bike’s performance and comfort. The sag setting directly impacts your bike’s handling, suspension efficiency, and rider comfort. This guide will walk you through the process of setting up sag for your Monarch RT3, troubleshooting common setup issues, and offering tips on customization and optimization for better performance.

Tools Required

  • Shock pump with pressure gauge
  • 2-3 zip ties or a shock sag indicator
  • Wrench or appropriate tool to adjust shock mounting bolts
  • Tape measure (for measuring your rider’s weight)

Understanding Sag and Its Importance

Sag refers to the amount the suspension compresses under the rider’s weight when the bike is at rest. For rear shocks like the Monarch RT3, sag is critical in ensuring that your bike’s suspension works efficiently and maintains proper geometry. Setting sag correctly ensures that the shock can absorb impacts without bottoming out or feeling too stiff. It also allows the suspension to stay in its optimal range for most of your riding.

Step-by-Step Guide to Setting Sag on the Monarch RT3

1. Determine Your Rider Weight and Recommended Sag Range

The first step is to determine your weight, as this will help you find the recommended sag range for your Monarch RT3 rear shock. The Monarch RT3 typically performs best with a sag range of 15-30% of the shock’s total travel. The exact percentage depends on your weight, riding style, and bike geometry.

  • For lighter riders, aim for the lower end of the range (15-20%).
  • Heavier riders or those who ride aggressively may benefit from the upper end (20-30%).

2. Set Initial Air Pressure

Before adjusting the sag, set the initial air pressure in the Monarch RT3. This is the base pressure that you’ll use to begin the setup.

  • Use a shock pump to inflate the shock to the recommended pressure based on your rider weight. The Monarch RT3 has a pressure chart printed on the shock or available online.
  • Pump the shock to the initial setting but don’t worry about fine-tuning the pressure just yet.

3. Install the Shock Sag Indicator

A simple method for measuring sag is using zip ties or a dedicated sag indicator. Place the zip tie around the shock’s stanchion or use a specific tool to mark your sag.

  • With the shock mounted and the initial air pressure set, slide the zip tie up the shock’s stanchion.
  • Get on your bike and assume your normal riding position. It’s essential that you wear all the gear you would typically use, as this affects the sag.
  • Once you are settled on the bike, gently dismount, keeping the bike upright. This will leave the zip tie in the position where your suspension has compressed under your body weight.

4. Measure the Sag

Measure the distance the zip tie has moved. This is the amount of sag, and you need to compare it to the total shock travel to ensure it falls within the recommended range.

  • For example, if your Monarch RT3 has 120mm of travel and you want to aim for 20% sag, your target sag would be 24mm.
  • If your zip tie is further than this, reduce the air pressure slightly and retest.
  • If the zip tie is less than this, add more air to the shock.

5. Fine-Tune the Air Pressure

Once you’ve measured the sag, you can fine-tune the air pressure to hit the target value.

  • Adjust the shock pressure incrementally, adding or releasing air in small amounts.
  • Re-test the sag after each adjustment and make sure to check it multiple times for consistency.

6. Check for Proper Functionality

After setting the correct sag, test ride your bike to check that the suspension feels right for your riding style.

  • The suspension should feel responsive to small bumps without feeling too harsh. On larger impacts, it should absorb the force without bottoming out or feeling excessively soft.
  • If the suspension feels too harsh or too soft, further adjustments to the air pressure may be necessary.

7. Lockout and Compression Adjustment

The Monarch RT3 features a three-position compression adjuster, which helps control the shock’s responsiveness to terrain. The settings include:

  • Open: Full compression damping for normal trail riding.
  • Pedal: Medium compression damping for climbing or efficient pedaling.
  • Lockout: Maximum damping for firm riding conditions (e.g., on smooth, flat surfaces).

Make sure to experiment with these settings to match your riding preferences.

Troubleshooting Common Sag Setup Issues

1. Suspension Bottoming Out

If you notice that your suspension bottoms out frequently, this may indicate that the air pressure is too low or your sag setting is too soft.

  • Solution: Increase the air pressure slightly to reduce bottoming out. Re-check sag after adjusting.

2. Suspension Too Stiff

If the suspension feels too stiff and doesn’t provide enough comfort or compliance over small bumps, your air pressure may be too high, causing insufficient sag.

  • Solution: Lower the air pressure slightly to achieve more sag and improve comfort.

3. Not Enough Rebound Control

While sag affects how the shock compresses, rebound control impacts how quickly the shock returns to its extended position.

  • Solution: Check the rebound adjuster on the Monarch RT3 and dial it to your preference. Slower rebound will allow the shock to return more gradually, which is useful on rough terrain.

Customization and Optimization for Better Performance

  • Adjusting Air Volume: The Monarch RT3 allows you to adjust the air volume by swapping out the volume reducers. This can help you fine-tune the shock for better mid-stroke support or a more progressive feel.
  • Changing Rebound Settings: Experiment with the rebound damping settings to control the shock’s return after compression. If you ride aggressively or on technical terrain, slightly slower rebound might improve control.
  • Compression Settings: Play with the Monarch RT3’s three-position compression settings to optimize your ride for different terrain types. This allows you to adjust the shock’s responsiveness depending on the conditions.

Comparison with Similar Models

When comparing the RockShox Monarch RT3 to other rear shocks, consider the following:

  • Monarch RT3 vs. Deluxe RT3: The Monarch RT3 offers more tunability with a three-position compression adjuster, while the Deluxe model offers slightly more progressive compression tuning.
  • Monarch RT3 vs. Fox Float: Fox Float shocks tend to offer a more refined and plush feel, but the Monarch RT3 is known for its easy setup and reliable performance, making it an excellent choice for riders who prefer straightforward adjustability.

Compatibility with Other Drivetrain Components

The Monarch RT3 is compatible with most modern drivetrain systems, but it’s important to ensure that your bike’s geometry and suspension are well-matched. The Monarch RT3’s adjustable air pressure makes it adaptable to different riders’ needs, but always check the compatibility with your frame’s shock mount spacing and travel length.