1. Introduction
This manual provides essential information for the proper installation, operation, and maintenance of your DNM AO-39RC mountain bike rear air shock. Designed for optimal damping adjustment, this shock allows fine-tuning of rebound and compression settings to match your riding style and terrain. Please read these instructions thoroughly before installation and use to ensure safe and effective performance.
2. What's in the Box
Verify that all components are present before beginning installation:
- DNM AO-39RC Rear Shock Absorber
- Mounting Hardware
3. Setup
3.1. Installation
Install the DNM AO-39RC rear shock absorber onto your bicycle frame using the provided mounting hardware. Ensure all bolts are tightened to the bicycle manufacturer's recommended torque specifications. Incorrect installation can lead to damage or injury.
3.2. Air Pressure Adjustment
The DNM AO-39RC features an American valve for air pressure adjustment. Use a high-pressure shock pump (not included) to adjust the air pressure. The maximum air pressure for the main chamber is 275 PSI. Refer to the image below for valve locations and recommended pressure ranges.
Image: Labeled components of the DNM AO-39RC rear shock, highlighting the Main Air Chamber Valve and Negative Air Chamber Valve.
Main Air Chamber: Inflate to your desired pressure based on your weight and riding style. Consult your bike's manual or a suspension setup guide for initial pressure recommendations.
Negative Air Chamber: The negative air chamber pressure must not exceed the main chamber pressure. This chamber helps with small bump compliance and initial stroke sensitivity.
3.3. Setting Sag
Sag is the amount your suspension compresses under your own weight. Proper sag is crucial for optimal performance. Typically, sag should be set between 25-35% of the shock's travel. Consult your bicycle manufacturer's recommendations for precise sag settings.
- Measure the eye-to-eye length of the shock when fully extended.
- Sit on your bike in your normal riding position (with gear).
- Measure the eye-to-eye length again.
- The difference is your sag. Adjust air pressure in the main chamber to achieve the desired sag.
4. Operating Adjustments
4.1. Rebound Adjustment
The rebound adjustment knob controls the speed at which the shock extends after compression. This allows you to fine-tune the shock's response to terrain.
Image: Rebound adjustment dial and its effect on shock performance.
- Clockwise (S): Increases damping, resulting in a slower rebound. Suitable for widely spaced, high-intensity impacts.
- Counter-clockwise (F): Decreases damping, resulting in a faster rebound. Suitable for closely spaced obstacles with low impact intensity.
4.2. Lockout Feature
The AO-39RC features a 3-stage lockout switch to adapt to different riding conditions.
Image: Lockout switch positions and their corresponding riding conditions.
- Lockout Status: Ideal for road cycling or climbing, providing a firm platform.
- Semi-Lockout Status: Suitable for light off-road trails, offering some suspension travel.
- Open Status: Full suspension travel for rough terrain and aggressive off-road riding.
5. Maintenance
Regular maintenance ensures the longevity and performance of your DNM AO-39RC rear shock.
- Cleaning: After each ride, clean the shock body and shaft with mild soap and water. Avoid high-pressure washers directly on seals.
- Inspection: Periodically check for any signs of damage, leaks, or excessive wear on the seals and bushings.
- Air Pressure: Check air pressure before each ride and adjust as necessary.
- Service: For internal service, such as seal replacement or damper fluid changes, it is recommended to consult a professional bicycle mechanic or authorized service center.
6. Troubleshooting
If you encounter issues with your DNM AO-39RC shock, refer to the following common problems and solutions:
| Problem | Possible Cause | Solution |
|---|---|---|
| Loss of air pressure | Leaking valve core, damaged seals | Check valve core for tightness, replace if necessary. Inspect seals for damage; professional service may be required. |
| Poor damping performance (too bouncy or too slow) | Incorrect rebound setting, low air pressure, internal damper issue | Adjust rebound knob. Check and adjust air pressure. If problem persists, seek professional service. |
| Lockout not engaging fully | Cable tension (if applicable), internal mechanism issue | Ensure lockout lever is fully engaged. If cable-actuated, check cable tension. Professional service may be required. |
7. Specifications
The DNM AO-39RC rear air shock is available in various eye-to-eye lengths and travel options. Key features include rebound adjustment, lockout, and adjustable air pressure.
Image: DNM AO-39RC specifications including length, travel, weight, and maximum air pressure.
| Feature | Description |
|---|---|
| Model | AO-39RC |
| Riding Style | XC / TRAIL |
| Shaft Material | Dark hard-anodized AL-7075, Ø 10mm (0.39 in) |
| Shock Body Material | Dark hard-anodized AL-6061 |
| Valve Type | American Valve |
| Max Air Pressure | 275 PSI (Main Chamber) |
| Available Sizes (Eye-to-Eye x Travel) | 165x35mm (6.50x1.38 in), 190x50mm (7.83x1.97 in), 200x55mm (7.87x2.17 in) |
| Features | Rebound Adjustment, 3-Stage Lockout, Dual-Chamber Design |
8. Warranty and Support
8.1. Warranty Information
This product comes with a limited 1-year manufacturer's warranty. Please retain your proof of purchase for any warranty claims. The warranty covers manufacturing defects but does not cover damage due to improper installation, misuse, neglect, or normal wear and tear.
8.2. Customer Support
If you have any questions regarding the installation, operation, or maintenance of your DNM AO-39RC rear shock, please contact our customer support. We are committed to assisting you within 24 hours.
For support, please refer to the contact information provided by your retailer or the official DNM website.