When Specialized created the Aethos, it wasn’t to win medals or chase regulations. It was to bring back the essence of road cycling: simplicity, freedom, and the pure love of the ride. Four years after redefining what a road bike could be, the Aethos returns in its second generation—lighter, more refined, and more versatile. The new Aethos 2 Pro with Shimano Ultegra Di2 offers a perfect balance of performance, durability, and value. It takes the world’s lightest disc road frame and pairs it with Shimano’s benchmark 12-speed Ultegra Di2 groupset, creating a build that delivers elegance, speed, and reliability in equal measure.

The frame remains the soul of Aethos. At just 595 grams for the 12r carbon layup—or 705 grams in the more accessible 10r carbon used on Pro models—it is still the lightest road frame on Earth. Specialized’s engineers achieved this through Flow State Design, a revolutionary method of sculpting tubes based on how forces move through the structure. Instead of relying on extra stiffness layers of carbon, they reshaped the frame to allow energy to flow efficiently. The result is a lighter chassis that is stronger and smoother, delivering sublime ride quality without compromise.

Strength and durability were non-negotiable. In testing, the Aethos endured over 100,000 pedal cycles at 2,377 watts—punishing loads far beyond industry norms—without a crack. It’s proof that the world’s lightest disc road frame is also one of the most robust. Riders can descend with confidence, climb relentlessly, and explore further, knowing the frame has been engineered for both weight savings and real-world resilience.

Geometry refinements are a hallmark of Aethos 2. Using insights from over 100,000 Body Geometry fits, Specialized adjusted the frame for improved comfort and stability. A taller stack reduces pressure on hands and shoulders. A slightly slacker head tube and lower bottom bracket deliver smooth, planted handling. A longer wheelbase brings stability without dulling responsiveness. These subtle changes combine to create an “in-the-bike” sensation that encourages longer, faster, and more confident rides. The Aethos 2 keeps the precise, lively handling riders loved, now with more ergonomic fit across a wider range of riders.

Versatility is also expanded. Aethos 2 now clears 35mm tires, giving riders access to greater comfort, grip, and the ability to explore more roads and surfaces. Despite this broader capability, the Pro frame remains exceptionally light thanks to painstaking carbon layup refinements and weight savings across the bike. Even small components—from the seatpost collar to brake mounts—were redesigned to shed grams while preserving strength. The result is a complete Pro build with Shimano Ultegra Di2 weighing just 6.73 kilograms, an astonishing figure for a bike in this category.

The Shimano Ultegra Di2 groupset is the perfect match for this platform. Long regarded as the performance workhorse of pro-level cycling, Ultegra Di2 brings the same precision as Dura-Ace with only a small weight penalty. Its 12-speed electronic shifting is instantaneous and effortless, delivering smooth gear changes even under load. The ergonomics of the levers are refined for comfort, while the braking system provides controlled power with excellent modulation. Ultegra’s proven reliability means it’s as ready for long alpine climbs as it is for weekend rides, offering pro-level performance with everyday dependability. Paired with the featherweight Aethos 2 frame, it creates a bike that is both cutting-edge and approachable.

The build is completed with Specialized’s Roval Alpinist components. The new Alpinist Cockpit II weighs only 270 grams and features ovalized tops, a four-degree flare for natural wrist alignment, and nearly 30 percent more vibration damping for reduced fatigue. Internal cable routing preserves a sleek aesthetic. The Roval Alpinist CLX III wheelset continues the ultralight theme, weighing just 1,131 grams. Featuring new Aero Composite spokes and DT Swiss 180 internals, they balance minimal weight with exceptional strength and durability. Hooked rims ensure secure tire retention and optimal tubeless performance, making them as practical as they are fast.

The Aethos 2 Pro with Shimano Ultegra Di2 embodies the spirit of the Aethos project: a bike designed not for the rulebook, but for the rider. It delivers sublime ride quality, unmatched lightness, and precise handling, paired with a drivetrain known for its dependability and performance. It’s the choice for riders who want the magic of the world’s lightest disc road frame paired with the confidence of Ultegra Di2—a machine that balances elegance with everyday rideability.

At 6.73 kilograms complete, this bike is more than a statistic. It’s a promise of speed on the climbs, control on the descents, and joy on every ride. The Aethos 2 Pro is proof that performance and simplicity are not opposites, but partners. It’s a bike built not just for racing, but for rediscovering the pure love of riding.