This post explains what OMEGA oil-pneumatic rear shocks are, how they differ from traditional spring shocks, and how to properly size, adjust, and maintain them on the 72V ONYX RCR.
It starts with a simple overview of how they work, then moves into pressure tuning, sizing options, nitrogen refills, sourcing, and bushing compatibility.
Quick Overview
If you just want the essentials:
- OMEGA shocks use oil + nitrogen instead of springs
- Pressure controls stiffness and rebound
- Stock pressure is ~29 PSI (2 bar)
- Typical tuning range is 20-25 PSI
- Available in multiple lengths for RCR and CTY2
- Stock ONYX bushings can be reused
What Are OMEGA Shocks?
OMEGA shocks are a modern revival of a ’90s racing design used on MBK and Peugeot competition bikes.
Instead of steel springs, they rely on:
- A sealed oil damping system
- Nitrogen pressure for spring force
- Precision pistons for rebound control
This design delivers:
- Smooth response
- Consistent damping
- Reduced fade under aggressive riding
OMEGA Shock Pressure & Adjustment
Before adjusting, measure the current pressure using a tire gauge.
Recommended process:
- Stock pressure: 29-31 PSI
- Release nitrogen in short bursts
- Target: 25 PSI for softer ride
- Optional: 20 PSI for maximum comfort
Always adjust slowly and test ride between changes.
Atmospheric Air Warning
Never fill OMEGA shocks with regular air.
Atmospheric air introduces moisture, which causes:
- Seal degradation
- Oil contamination
- Reduced damping performance
- Long-term internal corrosion
Nitrogen Refills
Nitrogen refills are simple and inexpensive.
Best source:
- Local welding supply shops
They can refill the shock bladder safely with dry nitrogen.
Rear Shock Length Options
| Model | Fitment | Length Range |
|---|---|---|
| Standard | RCR / CTY2 | 340mm - 360mm |
| Shorty | RCR / CTY2 | 290mm - 320mm |
Choose based on desired ride height and geometry.
Where to Buy OMEGA Shocks
Treatland
50Factory
Replacement Bushings
Stock ONYX bushings can be reused, or replaced.
Available at Treatland:
Bushing Dimensions
Stock ONYX RCR / CTY / CTY2
| Location | Outer | Inner | Length |
|---|---|---|---|
| Top | 14mm | 8mm | 19.5-21mm |
| Bottom | 14mm | 8mm | 19.5-21mm |
OMEGA Shocks
| Location | Outer | Inner | Length |
|---|---|---|---|
| Top | 14mm | 10mm | 19.5mm |
| Bottom | 14mm | 8mm | 19.5mm |
Eyelets:
- One side: 8mm ID
- One side: 10mm ID
- Eyelet-to-eyelet length varies by model
Final Notes
- Use nitrogen only
- Adjust pressure gradually
- Choose length carefully
- Reuse or replace bushings as needed
- Check pressure periodically
Properly tuned OMEGA shocks dramatically improve comfort, traction, and control on the ONYX RCR.