Specialized Aethos Pro and Expert models announced with 699g frame weight

After launching its brand new road bike, the Aethos, Specialized has added to the range with an Expert model that boasts a claimed weight of 7.14kg in the Ultegra Di2 build and two Expert models that bring that weight down to a very respectable 6.58kg when built with Ultegra Di2.

The Pro and Expert models feature a move from Specialized’s Fact 12r carbon to its slightly cheaper Fact 10r layup. This brings the price of the bikes down with the Pro being offered with Shimano Ultegra Di2 for £7,250 and SRAM Force eTap AXS at £7,500. The single Expert Ultegra Di2 option costs £5,500.

Specialized says that the move from Fact 12r carbon to Fact 10r carbon takes the frame up from 585g to a claimed 699g, though which size this relates to is unclear. When we first saw the Aethos in it's S-Works guise, the £10,750 Dura-Ace model came in at a very impressive 6kg. The Fact 10r frame and spec changes used for the Pro and Expert models add a little weight with the Pro Di2 model coming in at a claimed 6.58kg, the Pro eTap weighing a claimed 6.82kg and the Expert model with Di2 being the heaviest at a claimed 7.14kg. 

Lightweight v aero: which is best?

 Specialized is only offering the Aethos with disc-brakes and electronic shifting in their stock builds, but they say that you can put mechanical shifting on the Fact 10r frames should you wish. 

There are some other spec changes, such as the move from the Alpinist CLX wheels to the more affordable CL version, but all models get the new Alpinist carbon seatpost and Specialized is keen to point out that the design, geometry and crucially, the ride characteristics remain unchanged from the £10,750 S-Works model.

The Aethos was launched last month with an interesting design concept and a headline claim of being the lightest disc brake road bike ever made. Mat went into the detail surrounding the design process that Specialized says was developed for the Aethos but we’ll give you a summary if you’ve forgotten.

Specialized engineers Peter Denk and Sebastian Sevet felt that there could be massive improvements in the bike industry’s understanding of how cornering, pedalling and braking forces flow through a frame. They turned to a supercomputer to do some “staggeringly large calculations” to determine the optimum tube shapes and this is the result.

The Aethos essentially uses slightly altered round tube shapes and Specialized says that the layup of the carbon was changed to remove unnecessary “stiffness layers.”

“By utilising larger, longer, and more continuous, unbroken plies, we were able to achieve more consistent positioning than on any frame we’ve made before.

“The wall thicknesses of the tubes themselves are substantial throughout the frame, but because of the smaller number of the stiffness layers, the overall weight went down significantly.”

The overall weight is certainly still impressive for a disc brake road bike at 6.58kg for the Pro Ultegra Di2 model. You’d still be adding weight if you wanted to race it and it comes close to matching the S-Works Tarmac SL6 Dura-Ace rim-brake bike (6.35kg) and is a fair bit lighter than the Tarmac SL7 Pro Ultegra Di2 disc-brake (7.3kg). So if weight matters but you must have disc brakes and don’t care about aero then the Aethos is certainly an option worth considering.

The Aethos continues with Specialized's, and many other larger brands' move back to threaded bottom bracket systems. Here we have the classic 68mm BSA system just like in the Tarmac SL7. We've seen a similar move from Trek with the 2021 Emonda that now gets the T47 standard. Like the SL7, the Aethos will also take up to 32mm road tyres on 21mm internal rims. 

The frame uses the now-standard 142x12 and 100x12 thru-axles and follows Shimano’s flat mount disc brake standard.

Here are the specs of the three bikes:

Aethos Pro SRAM Force eTap AXS - £7,500

FRAME - Aethos FACT 10r Carbon, Rider First EngineeredTM, Threaded BB, 12x142mm thru-axle, flat-mount disc
FORK FACT - Carbon, 12x100mm thru-axle, flat-mount disc
HANDLEBARS - S-Works Short & Shallow
STEM - Specialized Pro SL, alloy, 4-bolt
TAPE - Supacaz Super Sticky Kush
SADDLE - Body Geometry Power Pro, Hollow Titanium Rails, Carbon Fiber Base
SEATPOST - Roval Alpinist Carbon Seatpost
FRONT BRAKE - SRAM Force eTAP, hydraulic disc
REAR BRAKE - SRAM Force eTAP, hydraulic disc
FRONT DERAILLEUR - SRAM Force eTAP AXS, braze-on
REAR DERAILLEUR - SRAM Force eTAPAXS, 12-speed
CRANKSET - SRAM FC Force DUB, 12-speed
CHAIN - SRAM Force, 12-speed
FRONT WHEEL - Roval Alpinist CL, 21mm internal width carbon rim, 33mm depth, Win Tunnel Engineered, DT for Roval 350 hub, DT Swiss Aerolite spokes
REAR WHEEL - Roval Alpinist CL, 21mm internal width carbon rim, 33mm depth, Win Tunnel Engineered, DT for Roval 350 hub, DT Swiss Aerolite spokes
FRONT TYRE - S-Works Turbo, 120 TPI, folding bead, BlackBelt protection, 700x26mm
REAR TYRE - S-Works Turbo, 120 TPI, folding bead, BlackBelt protection, 700x26mm

Aethos Pro Ultegra Di2 - £7,250

FRAME - Aethos FACT 10r Carbon, Rider First EngineeredTM, Threaded BB, 12x142mm thru-axle, flat-mount disc
FORK FACT - Carbon, 12x100mm thru-axle, flat-mount disc
HANDLEBARS - S-Works Short & Shallow
STEM - Specialized Pro SL, alloy, 4-bolt
TAPE - Supacaz Super Sticky Kush
SADDLE - Body Geometry Power Pro, Hollow Titanium Rails, Carbon Fiber Base
SEATPOST - Roval Alpinist Carbon Seatpost
FRONT BRAKE - Shimano Ultegra R8070, hydraulic disc
REAR BRAKE - Shimano Ultegra R8070, hydraulic disc
FRONT DERAILLEUR - Shimano Ultegra Di2 R8050, braze-on
REAR DERAILLEUR - Shimano Ultegra Di2 R8050, GS medium cage
CRANKSET - Shimano Ultegra R8000, HollowTech 2, 11-speed
CHAIN - Shimano Ultegra, 11-speed
FRONT WHEEL - Roval Alpinist CL, 21mm internal width carbon rim, 33mm depth, Win Tunnel Engineered, DT for Roval 350 hub, DT Swiss Aerolite spokes
REAR WHEEL - Roval Alpinist CL, 21mm internal width carbon rim, 33mm depth, Win Tunnel Engineered, DT for Roval 350 hub, DT Swiss Aerolite spokes
FRONT TYRE - S-Works Turbo, 120 TPI, folding bead, BlackBelt protection, 700x26mm
REAR TYRE - S-Works Turbo, 120 TPI, folding bead, BlackBelt protection, 700x26mm

Aethos Expert Ultegra Di2 - £5,500

FRAME - Aethos FACT 10r Carbon, Rider First EngineeredTM, Threaded BB, 12x142mm thru-axle, flat-mount disc
FORK FACT - Carbon, 12x100mm thru-axle, flat-mount disc
HANDLEBARS - Expert Short & Shallow
STEM - Specialized Pro SL, alloy, 4-bolt
TAPE - Supacaz Super Sticky Kush
SADDLE - Body Geometry Power Expert, Hollow Titanium Rails
SEATPOST - Roval Alpinist Carbon Seatpost
FRONT BRAKE - Shimano Ultegra R8070, hydraulic disc
REAR BRAKE - Shimano Ultegra R8070, hydraulic disc
FRONT DERAILLEUR - Shimano Ultegra Di2 R8050, braze-on
REAR DERAILLEUR - Shimano Ultegra Di2 R8050, GS medium cage
CRANKSET - Shimano Ultegra R8000, HollowTech 2, 11-speed
CHAIN - Shimano Ultegra, 11-speed
FRONT WHEEL - DT R470 Disc, sealed cartridge hubs, 14g spokes, 24h
REAR WHEEL - DT R470 Disc, sealed cartridge hubs, 14g spokes, 24h
FRONT TYRE - S-Works Turbo, 120 TPI, folding bead, BlackBelt protection, 700x26mm
REAR TYRE - S-Works Turbo, 120 TPI, folding bead, BlackBelt protection, 700x26mm

specialized.com