These S-Works Aethos Ultegra Di2 complete bikes are frameset-up, Excel Sports builds, and while these may share some common items with a Specialized build, there are differences in some components and pricing. If you have any questions about these bikes, please contact sales@excelsports.com or call our Sales team during business hours at 800.627.6664.

Our S-Works Ultegra bike has a build featuring the partially wireless Ultegra Di2- and the package rolls on R1870 wheels The S-Works Aethos frame weighs just 585 grams and this build results in a sub 15lb build that is fully capable for all the requirements of road cycling, even racing. Of course you'd need to add some weight, as it sits below the UCI weight limit at 14.29 lbs as built. And although the S-Works Aethos carries a race geometry, it was engineered and developed to offer the apex cycling experience for the serious enthusiast who appreciates the ultimate in quality and design, with a ride quality and handling to match.

The story of the Aethos is pure Specialized. The achievement of the frameset design represents virtually all of the foundational principles of the company, except one. For one of the leading proponents of aerodynamic design for road cycling and racing, as exemplified by the Tarmac SL7, aerodynamics was never factored in to the development of the Aethos. The engineering problem of building the lightest, most exceptional riding road bike was incredibly appealing. Having solved unbelievably complicated problems with the SL7, they may not have anticipated new and more efficient applications of carbon fiber, or that as a result they'd discover a Continuous Curvature Design strategy. The end result of Aethos process pushed the most innovative team in cycling development to new heights.

The Aethos frame has been designed with the perfect combination of ultimate ride feel, light weight, and style. This was achieved by reinventing the traditional road tube shapes found on bikes of the past, subtly altering these visual shapes to deliver massive gains in stiffness and balance, all without affecting weight or durability. That visual story appears simple on some level, but it was the application of carbon technology and incredible engineering capabilities to find the stress loads, tube thicknesses, and how to best integrate all of the shapes and engineering requirements in ways you can't see to create the Aethos. This new process, with an entirely-new layup system tapped into the R&D system Specialized has perfected over multiple decades.

The creation and engineering story is ripe for a graduate course offering, so the discussion must turn on the possibilities and rationale of the rider experience. A featherweight frame is useless without confidence-inspiring ride characteristics, which is the team developed the Aethos to have the perfect balance of front and rear stiffness combined with exceptional overall ride quality. By studying the flexing and breathing of carbon fiber, the testers were able to discover groundbreaking findings about how forces flow through frames. Every detail has been designed with style, weight, and durability in mind; everything required in pursuit for the perfect ride. The geometry is exceptionally close to that of the Tarmac SL7, with a few modifications that may add up to a subtle handling difference if you were comparing each bike built with the same exact kit.

The electronic shifting-only Aethos frameset is equipped with a 27.2mm round seatpost, the Roval Alpinist to be exact, which offers some engineered flex into the upper portion that adds to the frame compliance and weighs a scant 136 grams in the 300mm length. Not to worry, it (and the frameset) is rated for a rider weight up to 275lbs. The frame and fork can accommodate tires up to 32mm with 4mm of clearance on both sides. The fork steerer is round, accepting standard stem and bar set-ups. Every line, every junction just feels so economical and judicious in the use of materials. The subtleties are there, sometimes hidden by the amazing finish options, sometimes accentuated by them. The system is clean, simple.

This complete package features the steady, precise, and fast shifting prowess of Shimano's updated 12-speed Ultegra Di2 and improved hydraulic disc braking. The cockpit kit features Specialized an Alpinist seatpost and Power Saddle, while Zipp provides the carbon and alloy stem. The wheels are the aforementioned the Ultegra R817's, a C36 on the 56cm, and the deeper C50 on the 58cm. These are great all-around wheels, aided by the superb feel and grip of the 28mm Vittoria Corsa G2.0 Tubeless tires.