Profile Design Sonic/Ergo 39a clip-on aerobar system — 400mm extensions, 39° grip, adjustable Ergo armrests

The Profile Design Sonic/Ergo/39a is a lightweight, highly adjustable clip-on aerobar system that helps cyclists find faster, more comfortable time-trial and triathlon positions.

Built from durable aluminium and pairing the Sonic bracket with Ergo armrests, this aerobar was engineered to reduce frontal area while giving a broad range of fit options. Its 39° extension angle and 400mm extensions provide a balance of aerodynamic posture and ergonomic hand placement. With precise micro-adjustments across width, offset and stack, the Sonic/Ergo/39a suits riders who need repeatable, fine-tuned setups on road or race bikes.

How does the Sonic/Ergo/39a improve aerodynamics without sacrificing comfort?

The design narrows your frontal profile through slim, low-profile brackets and straight extensions, while the Ergo armrests give supportive contact points to sustain a tucked position. The 39° grip angle helps riders hold either a tucked or more open posture depending on preference.

• Minimal frontal area from compact Sonic bracket geometry
• Ergo armrests for wider pressure distribution and support
• 39° grip angle balances speed and control
• 400mm extensions allow longer reach for aerodynamic positioning

What level of adjustability can I expect for fit and fine-tuning?

This model provides an unusually large fit range for a clip-on bar, letting you dial in width, offset, rotation and stack in small increments. The top bolt and bracket system enable quick rotation and extension length changes, while the armrest platform moves in precise steps for repeatable setups.

• Armrest offset: -70mm to -17.5mm in 7.5mm steps
• Armrest width: 124mm to 290mm in 18.5mm steps (with 100mm extensions)
• Armrest stack: 60mm (no riser) up to 130mm with riser kits in 5mm steps
• Top bolt allows easy extension rotation and length adjustment

How much does the Sonic/Ergo/39a weigh and what are the core specs?

The unit is engineered to be light without compromising strength; total assembly weight is competitive for aluminium clip-on bars. The 39a uses Profile Design’s latest aluminium extension set and ships with Ergo armrests and 10mm pads for comfort.

• Weight: 564 g (complete bracket, extensions and armrests)
• Extension length: 400 mm
• Grip angle: 39° for the extensions
• Includes Ergo armrests with 10 mm pads

How easy is installation and compatibility with my bike?

As a clamp-on aerobar system, the Sonic/Ergo/39a mounts to most round or slightly oval aero bars with straightforward clamping hardware. Adjustment uses common hex tools and the modular design means you can combine risers or aftermarket kits to expand stack and reach.

• Clip-on clamp fits standard handlebars; check diameter compatibility
• Adjustments use accessible top bolts and allen fasteners
• Riser kits available for increased stack height and fine fit tuning
• Designed for repeatable setups and easy removal between bikes

Who is this for: The Profile Design Sonic/Ergo/39a is ideal for time trialists, triathletes and committed road riders who want a highly configurable, lightweight aluminium clip-on aerobar. If you value a broad range of micro-adjustments to refine aerodynamics and sustain comfort during long efforts, this bar delivers professional-level fit options without moving to full integrated aerobars.