Subsonic 39a Aerobar
The Subsonic/Ergo/39a aerobar combines the low stack Subsonic bracket with the arm-hugging Race armrest to offer an industry-leading fit range oriented toward low, narrow positions. The 39a extension provides a comfortable 39-degree angle with an 87mm rise. This is the only low stack clip-on aerobar on the market that maintains the pad-to-grip angle as the bar is stacked up.
Subsonic is not just another aerobar bracket. It brings our next generation fit range to a low stack bracket design. This allows the bar to use our riser kits to increase stack height without changing the relationship between the armrest and the grips.
The Ergo armrest is designed to tightly cup the rider's arms, facilitating a narrow position and increasing control at speed.
Performance
The Subsonic/Ergo is designed to achieve a lower stack height than standard aerobars without the added frontal area of a below-the-basebar extension clamping system. This improves both aerodynamics and fit range.
Fit Data
- Armrest Offset: -85mm to -17.5mm in 7.5mm steps
- Armrest Width: 142mm to 272mm in 18.5mm steps (with extensions at 100mm)
- Armrest Stack: Minimum 40mm. Compatible with existing risers adding up to 70mm of stack in 5mm increments.
The extension rotation can be easily adjusted using the shaft bolt. There is a 40mm range of extension length adjustment once the extensions have been cut.
There are 80 distinct position options achievable by moving the armrests alone. When combined with risers, this bar offers 1200 possible configurations. As a clip-on bar, extension width and tilt can also be adjusted easily, making this the most adjustable low stack clip-on on the market.
Origin Story
After releasing the Supersonic (J5) as a premium bracket with market-leading fit options and versatility, we wanted to bring the same level of adjustability to the rest of our aerobar range.
Where the Supersonic and Sonic brackets have a minimum stack of around 60mm, similar to most popular aerobars, the Subsonic was designed to offer a substantially lower position. This helps riders who struggle to achieve their ideal fit on modern bike frames.
It was vital to include stack height adjustment without altering the pad-to-grip relationship, allowing riders to fine-tune every aspect of their setup.
The Ergo armrest shares the flippable design of our new generation armrests. By swapping sides or rotating the armrests, smaller increments of movement are achieved, making it easy to fine-tune a rider's position or replicate a previous setup.
Who Is It For
This bar is ideal for riders seeking lower positions than those possible with standard aerobar designs. Unlike other low stack bars, it allows fine-tuning of stack height so riders are not limited to a single armrest height.
With Race armrests fitted, it is tailored for riders aiming to be low and narrow to punch the smallest possible hole through the wind.
Tech Specs
- Bracket: Subsonic
- Clamp Diameter: 31.8mm (26.0mm with Shim Kit, sold separately)
- Armrest: Ergo / 10mm Pads
- Extension Length: 340mm
- Width: 142mm to 272mm
- Weight: 590g
- Color: Black
Tech Guide
Torque Settings
- Bar Clamp: 6Nm
- Extension Clamp: 5Nm
- Armrest Bolts: 4.7Nm
Weight Breakdown
- Bracket: 304g
- Armrest: 148g
- Extensions: 186g
- Total: 590g