1. Introduction
Thank you for choosing the DNM AO-39RC MTB Air Shock Absorber. This manual provides essential information for the proper installation, operation, and maintenance of your new shock absorber. Designed for mountain bikes, including All Mountain, Freeride, Downhill, XC, and Trail riding styles, the AO-39RC features a dual-chamber design, rebound adjustment, and a 3-stage lockout system to deliver enhanced damping performance and a smoother ride across various terrains.
2. Product Overview
2.1 Key Features
- Dual-Chamber Design: The primary and secondary air chambers work in coordination to deliver enhanced damping performance.
- Rebound Adjustment: Allows fine-tuning of the shock's return speed.
- 3-Stage Lockout: Provides versatile damping control for different riding conditions.
- Durable Construction: Main body made of high-strength, lightweight aluminum alloy.
2.2 Components
Familiarize yourself with the main components of your AO-39RC shock absorber:
- Damping Adjustment Knob: Used to adjust the rebound speed.
- Lockout Switch: Controls the 3-stage lockout function (Lockout, Semi-Lockout, Open Status).
- Main Air Chamber Valve: For adjusting the main air pressure.
- Negative Air Chamber Valve: For adjusting the negative air pressure.
3. Specifications
The DNM AO-39RC is available in three lengths, each with corresponding travel and weight specifications:
| Attribute | 165mm Model | 190mm Model | 200mm Model |
|---|---|---|---|
| Model Number | AO-39RC | ||
| Length | 165mm | 190mm | 200mm |
| Travel | 35mm | 50mm | 55mm |
| Weight (including bushing) | 293g | 315g | 324g |
| Hole Size | 8mm x 24mm | ||
| Adjustments | Rebound, Lockout, Adjust High Pressure | ||
| Damper Shaft | Dark hard-anodized AL-7075 Ø 10 mm (0.39 inch) shaft | ||
| Shock Body | Dark Hard Anodized Aluminum 6061 | ||
| Spring Type | Air Spring | ||
| Valve Angle | 30 Degree | ||
| Max Air Pressure | Not Exceeding 275 PSI | ||
| Intended Use | All Mountain, Freeride, Downhill, XC / Trail | ||
| Origin | Made in Taiwan | ||
4. Setup
4.1 Installation
The shock absorber comes with bushings. The default bushing size is 8mm x 24mm (Top and Below). If your bike frame requires different bushing sizes, please ensure you have the correct ones before installation. Consult a professional bike mechanic if you are unsure about the installation process.
4.2 Initial Air Pressure Adjustment
Proper air pressure is crucial for optimal performance and rider safety. Use a high-pressure shock pump to adjust the air chambers.
- Maximum Air Pressure: Do not exceed 275 PSI in the main air chamber.
- Negative Chamber Pressure: The pressure in the negative air chamber must NOT exceed the pressure in the main air chamber.
Adjust the air pressure according to your weight and riding style. Start with the manufacturer's recommended sag settings for your bike frame, typically 25-30% of the shock's travel.
5. Operating Instructions
5.1 3-Stage Lockout
The AO-39RC features a versatile 3-stage lockout system controlled by the lockout switch:
- Lockout Status: Ideal for road cycling or climbing, providing a firm platform.
- Semi-Lockout Status: Offers a balance between efficiency and small bump compliance, suitable for light off-road use.
- Open Status: Fully active suspension for maximum bump absorption on rough terrain and descents.
5.2 Rebound Adjustment
The rebound adjustment knob controls the speed at which the shock extends after compression. Adjusting the rebound damping allows you to fine-tune the shock's response to different terrains.
- Clockwise (S): Slower Rebound. Prioritize slower rebound speed for widely spaced, high-intensity impacts.
- Counterclockwise (F): Faster Rebound. Prioritize faster rebound speed for closely spaced obstacles with low impact intensity.
6. Maintenance
Regular maintenance ensures the longevity and optimal performance of your DNM AO-39RC shock absorber.
- Cleanliness: Keep the shock body and shaft clean from dirt and debris after each ride. Use a soft cloth and mild soap and water. Avoid high-pressure washers directly on seals.
- Seal Inspection: Periodically inspect the seals for any signs of wear, cracking, or leakage. Replace worn seals promptly.
- Air Pressure Check: Check air pressure before every ride and adjust as necessary.
- Bushing Inspection: Check bushings for play or wear. Replace if excessive movement is detected.
- Professional Service: For internal maintenance, such as oil changes or seal replacement, it is recommended to seek service from a qualified bicycle mechanic or an authorized DNM service center.
7. Troubleshooting
If you encounter issues with your shock absorber, refer to the following common troubleshooting tips:
| Problem | Possible Cause | Solution |
|---|---|---|
| Loss of air pressure | Leaky valve core, damaged seals | Check valve core for tightness, replace if necessary. Inspect seals for damage and replace if needed. |
| Shock feels too soft/hard | Incorrect air pressure | Adjust air pressure to recommended sag settings using a high-pressure pump. |
| Poor rebound performance (too fast/slow) | Incorrect rebound setting | Adjust the rebound damping knob (clockwise for slower, counter-clockwise for faster). |
| Lockout not engaging fully | Internal issue, cable tension (if applicable) | Ensure the lockout switch is fully engaged. If the issue persists, professional service may be required. |
| Squeaking or grinding noises | Lack of lubrication, worn bushings, dirt ingress | Clean and lubricate the shock shaft. Inspect and replace worn bushings. |
For issues not covered here or if problems persist, contact DNM customer support or a certified service center.
8. User Tips
- Sag Setting: Always set your sag with your full riding gear on. This ensures the most accurate and effective suspension performance for your weight and setup.
- Experiment with Settings: Don't be afraid to experiment with both air pressure and rebound settings to find what works best for your riding style and the terrain you frequent. Keep a small notebook to record settings.
- Regular Cleaning: A quick wipe-down of the shock shaft after each ride can significantly extend the life of your seals and prevent dirt from entering the system.
9. Warranty and Support
For warranty claims, technical support, or service inquiries, please refer to the official DNM website or contact your authorized dealer. Keep your proof of purchase for any warranty-related matters.