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Specialized S-Works Aethos geometryRoad · 2026 · 6 sizes, from 49 to 61

The Specialized S-Works Aethos is a road bike available in 6 sizes, from 49 to 61. Stack ranges from 522 to 627 mm and reach from 373 to 404 mm. Its position sits between racing and endurance. All sizes share 410 mm chainstays.

Stack522–627mm
Reach373–404mm
Head angle71.4–73.5°
Chainstay length410mm
Low BB

What size S-Works Aethos do I need?

Enter the stack and reach of a bike that fits you well and we will tell you which size is closest and how to set it up.

Compare on Fitbikefy →
49S 522 · R 373
52S 538 · R 377
54S 559 · R 384
56S 580 · R 391
58S 606 · R 398
61S 627 · R 404

Enter your stack and reach to see which size fits you best.

Geometry chart by size

Measurements in mm and degrees, as published by Specialized. The ones that matter most for choosing a size are in bold.

Size495254565861
Stack522538559580606627
Reach373377384391398404
Effective top tube508526544557572584
Head tube length114128150169198218
Head angle71.4°72.1°72.5°73.0°73.0°73.5°
Chainstay length410410410410410410
Wheelbase9789819929981,0131,020
Front centre581584594599614621
BB drop777775757474
BB height266266267267269269
Fork length372372372372372372
Fork offset505050474747
Trail625855555552
Standover719737759779805834
Seat tube (method not stated)450470490510535570
Seat angle (method not stated)75.5°74.5°74.0°74.0°74.0°74.0°

Source: Specialized official website · data from 11 Nov 2026.

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Specialized S-Works Aethos 2026

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Stack and reach of every size

Higher means a taller front end; further right means a longer reach. The blue dot is your search.

350360370380390400410420430480500520540560580600620640660reach (mm) →↑ stack (mm)495254565861

Character of each size

Compared with other road bikes. Further right means more of that quality.

49
52
54
56
58
61
Positionracing → relaxed
Steeringcalm → quick
Pedallingrearward → forward
Bottom brackethigh → low
Wheelbaselively → planted
Rear endstable → agile

Bikes with similar geometry (size 54)

The closest size of other road models, by stack and reach.

ModelΔ stackΔ reach
Specialized Aethos · 542026±0 mm±0 mmCompare →
Cube Attain SLX · 53 cm2026+2 mm±0 mmCompare →
Cube Attain · 53 cm2026+2 mm±0 mmCompare →
Wilier Triestina Rapida · M2027−3 mm+1 mmCompare →
Cannondale SuperSix EVO · 542026−4 mm±0 mmCompare →
Ridley Grifn RS Road · S2027+4 mm−1 mmCompare →
S-Works Aethos or Aethos? In size 54 they have exactly the same stack and reach (559 / 384 mm): the difference is in the frame and build, not the position.

Frequently asked questions

What size S-Works Aethos do I need?

It depends on your position, not just your height. The most reliable way is to compare the stack and reach of a bike that fits you with those of each size (from 522/373 mm in size 49 to 627/404 mm in size 61). The size finder on this page shows the closest size and the stem and spacers you would need.

What are the stack and reach of the S-Works Aethos in size 54?

Stack of 559 mm and reach of 384 mm, with an effective top tube of 544 mm and a head angle of 72.5°.

Is the S-Works Aethos a racing or an endurance bike?

In between. In size 54 its stack-to-reach ratio is at percentile 57 of road bikes: neither very low nor very tall.

Does it have the same geometry as the Aethos?

In size 54, yes: same stack and reach. If one already fits you, the same size of the other will put you in the same position.