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Specialized Aethos Size Chart

Shop new and used Specialized Aethos road bikes for sale with TPC - The Pro's Closet. Find the perfect sized Aethos by height and view geometry numbers and other info with TPC. 

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The Specialized Aethos is designed with an emphasis on creating an efficient, and comfortable ride. When sizing for the bike, several factors need to be taken into consideration to ensure the best fit.

Aethos Size Chart By Height

SizeHeight (Cm)Height (Inches)
49155 - 1635'1" - 5'5"
52163 - 1705'4" - 5'7"
54170 - 1755'7" - 5'9"
56175 - 1805'9" - 5'11"
58180 - 1885'11" - 6'2"
61188 - 1966'2" - 6'5"

Frame Size & Geometry 

The Aethos shares identical fit and handling geometry with the Tarmac SL7. It comes in various frame sizes including 49, 52, 54, 56, 58, and 61. The geometry for each frame size is detailed with measurements including stack, reach, head tube length, seat tube length, and angles among others. 

Specialized Aethos Geometry: 2020 - 2023

Crank Length165mm170mm172.5mm172.5mm175mm175mm
Handlebar Width380mm400mm420mm420mm440mm440mm
Stem Length80mm90mm100mm100mm110mm110mm
Saddle Width155mm155mm143mm143mm143mm143mm
Seatpost Length300mm300mm360mm360mm360mm360mm
Head Tube Length109mm120mm137mm157mm184mm204mm
Head Tube Angle71.75°72.5°73°73.5°73.5°74°
BB Height266mm266mm268mm268mm268mm268mm
BB Drop74mm74mm72mm72mm72mm72mm
Fork Length, Full369mm369mm369mm369mm369mm369mm
Fork Rake/Offset47mm47mm44mm44mm44mm44mm
Front Center574mm577mm579mm591mm606mm613mm
Chainstay Length410mm410mm410mm410mm410mm410mm
Top Tube Length, Horizontal508mm531mm540mm562mm577mm595mm
Bike Standover Height705mm728mm748mm769mm796mm824mm
Seat Tube Length431mm462mm481mm504mm532mm567mm
Seat Tube Angle75.5°74°74°73.5°73.5°73°

Saddle Height & Reach Adjustments

Correct saddle height is crucial for pedaling efficiency and comfort. The Aethos comes with a new Alpinist seatpost, with a minimum seatpost insertion from the top of the seatpost collar being 75mm and the maximum insertion being 215mm. It's advisable to adjust the saddle height to meet your comfort and efficiency needs. If the supplied seatpost does not meet these requirements for your appropriate saddle height, a shorter or longer seatpost may be needed​3​.

If the bike is the correct size, you should be able to comfortably reach the handlebars with your elbows slightly bent. The saddle can move back and forth on the rails—starting with it centered is recommended, and fine-tuning as needed. Additionally, reach can be adjusted by raising or lowering the handlebar height, and by increasing or decreasing the length of the bike stem. A maximum of 35mm of spacers may be placed beneath the stem, with a maximum of 5mm of solid spacers installed above the stem​​.

Bikes are meant
to be used.