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Here’s why the Specialized Aethos non-race bike is being raced in the Tour de France

The superbike they said would never race in the pro peloton makes its debut in the pro peloton

When the Tarmac SL7 was launched last year Specialized claimed it was “one bike to rule them all”, discontinuing the Venge aero bike in the process by being just as fast and sitting on the UCI's minimum weight limit. A couple of months later the Aethos was launched, an even lighter bike that Specialized insisted wasn't for racing, all but confirming we'd never see it in the pro peloton... so what’s Deceuninck–Quick-Step's Kasper Asgreen doing at the Tour de France on the S-Works Aethos frameset?

> Check out the 2021 Tour de France race bikes

2021 Kasper Asgreen Specialized Aethos 3

The Aethos frame is UCI-approved, but when it was unveiled in October of last year Specialized said it was aimed at riders who prioritise handling and ride quality above aerodynamics, and who want the ultimate high-performance road bike unrestricted by competition rules as complete builds can easily weigh in 800g below the UCI’s 6.8kg minimum limit. From what we can recall, Specialized were quite adamant it wasn't for pros because the Tarmac SL7 does everything they could possibly ask for - however, Asgreen's choice to ride the Aethos at Le Tour has put paid to that. 

2021 Kasper Asgreen Specialized Aethos 5

Check out Liam Cahill’s initial thoughts on the super lightweight ride below.

The Aethos is built around a 588g frame with complete bikes from 6kg, but the US brand says that it chased ride quality rather than weight in itself.

“The ride is truly stunning, with acceleration I've never felt before and handling that's just spot on,” Liam said when he reviewed the Aethos.

> Read his full review of the Specialized Aethos Pro Ultegra Di2 over here

Asgreen wants some of this smooth and impressive riding quality for himself and Specialized says the lightweight Aethos frame has allowed the Danish pro to make the strategic components choices while staying at the UCI minimum for weight.

2021 Kasper Asgreen Specialized Aethos 8

He is rolling on the 1,410g Roval Rapide CLX carbon clinchers he rode to win the Tour of Flanders earlier this year instead of the lightweight 1,250g Roval Alpinist CLX wheels.

> Review: Roval Alpinist CLX wheels

“Since Kasper plans to climb at a steady tempo in the mountains, he won’t need the light weight and reactivity of the Alpinist CLX wheels, but instead has chosen the Rapides for the aero advantage on the flats and descents,” explains Specialized.

2021 Kasper Asgreen Specialized Aethos 15

> Review: Roval Rapide CLX wheels

“With Kasper’s S-Works Aethos build, his drivetrain component selection will be similar to his Tarmac SL7.  While the remaining components aid in a weight reduction, their main benefit is the added assurance that he will reduce the overall fatigue experienced during the longer stages with more difficult terrain,” adds Cameron Piper, Specialized’s Product Manager for Tarmac SL7 and Aethos.

6.0kg: that’s how little the S-Works Aethos Dura-Ace Di2 model can weigh with the lightest colourway and built with the lightest components: Roval Alpinist CLX wheels, the S-Works SL stem and S-Works Short and Shallow carbon handlebar.

2021 Kasper Asgreen Specialized Aethos 16

To bring the complete build up to the UCI legal weight limit of 6.8kg, here’s the full spec breakdown of Asgreen’s mountain TDF bike:      

  • Frame: S-Works Aethos FACT 12r Carbon frame, Threaded BB, Electronic cable routing only, 12x142mm thru-axle, flat-mount disc
  • Fork: S-Works FACT Carbon, 12x100mm thru-axle, flat-mount disc         
  • Handlebars: Pro Vibe Aero 42cm
  • Stem: Pro Vibe 130mm
  • Tape: Supacaz Super Sticky
  • Saddle: Phenom Expert
  • Seatpost: Roval Alpinist Carbon Seatpost
  • Seat Binder: Specialized Alloy, 30.0mm, titanium bolt
  • Computer Mount: K-Edge Aero Race
  • Bottle Cages: Tacx Deva
  • Groupset: Shimano Dura-Ace Di2 11-speed, hydraulic disc
  • Gearing: 11-30t, 54/39t
  • Wheelset Roval Rapide CLX
  • Tyres: Turbo Cotton, 700x26mm
  • Inner Tubes: Latex

Add new comment


RobD | 2 years ago
1 like

I suppose it makes sense, if you know you're not going to be going for the win on mountainous stages and your job is to help guide Cav to the finish inside the time cut, you might as well be a little more comfortable while you do it. plus it's got a nice chunk of extra exposure for your sponsor so double win.

fenix | 2 years ago

"Because Specialized arent selling as many as they thought ?"


It's no longer lightweight as it has to meet the UCI minimum. 

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