Quiver

2025 Specialized Tarmac SL8 Team Soudal Quick-Step vs 2025 Specialized Aethos Pro

The Specialized Aethos Pro size closest to your 54 is the 54. Compare the 54 instead

What changes on the Specialized Aethos Pro

Compared with the Specialized Tarmac SL8 Team Soudal Quick-Step in 54, the Specialized Aethos Pro in 58 places the top of the head tube 47 mm higher and 18 mm further forward, relative to the bottom bracket. Its wheelbase is 27 mm longer, which can contribute to stability at speed.

Frame stack
+47 mm
Higher front end
Frame reach
+18 mm
Longer frame reach
Wheelbase
+27 mm
Longer: steadier at speed
Head angle
+0.5°
Steeper: sharper steering
Chainstays
±0 mm
About the same

The two frames

2025 Specialized Tarmac SL8 Team Soudal Quick-Step (54) and 2025 Specialized Aethos Pro (58), lined up at the bottom bracketBoth frames drawn to scale. The Specialized Tarmac SL8 Team Soudal Quick-Step is drawn in full with its measurements, and the Specialized Aethos Pro is the colored outline on top.J 978

Specialized Tarmac SL8 Team Soudal Quick-Step, 54Specialized Aethos Pro, 58Drawn to scale and lined up at the bottom bracket.

Geometry side by side

MeasurementSpecialized Tarmac SL8 Team Soudal Quick-Step 54Specialized Aethos Pro 58Difference
Reach384mm402mm+18 mm
Stack544mm591mm+47 mm
Head tube angle73°73.5°+0.5°
Seat tube angle74°73.5°−0.5°
Effective top tube541mm577mm+36 mm
Chainstay length410mm410mm±0 mm
Wheelbase978mm1005mm+27 mm
BB drop72mm72mm±0 mm
BB height268mm268mm±0 mm
Standover768mm796mm+28 mm
Seat tube length473mm532mm+59 mm
Fork length370mm369mm−1 mm
Head tube length137mm184mm+47 mm

Differences are the Specialized Aethos Pro minus the Specialized Tarmac SL8 Team Soudal Quick-Step. Full charts: 2025 Specialized Tarmac SL8 Team Soudal Quick-Step, 2025 Specialized Aethos Pro.

Where each sits in its class

Specialized Tarmac SL8 Team Soudal Quick-StepSpecialized Aethos Pro

AggressivePositionUpright
CalmSteeringQuick
PlayfulBalancePlanted

Each bike is ranked against the other road bikes on Quiver, on frame geometry alone. Not your hand position or ride feel.

What each ships with

The stock build of each bike's first listed trim. Parts that match are dimmed.

PartSpecialized Tarmac SL8 Team Soudal Quick-StepS-Works Team Soudal Quick-StepSpecialized Aethos Pro
FrameSpecialized S-Works Tarmac SL8 FACTnot listed

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Explore the app
A Transition Relay build sheet: frame, fork, shock and drivetrainThe Relay’s ride photo galleryThe Relay’s ride spectrum and 2D frame geometryThe garage: five bikes and 99 recorded partsA Specialized Tarmac SL8 road build sheet