Specialized Aethos Size Chart
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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
| Size | Height (Cm) | Height (Inches) |
| 49 | 155 - 163 | 5'1" - 5'5" |
| 52 | 163 - 170 | 5'4" - 5'7" |
| 54 | 170 - 175 | 5'7" - 5'9" |
| 56 | 175 - 180 | 5'9" - 5'11" |
| 58 | 180 - 188 | 5'11" - 6'2" |
| 61 | 188 - 196 | 6'2" - 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
| 49 | 52 | 54 | 56 | 58 | 61 | |
| Crank Length | 165mm | 170mm | 172.5mm | 172.5mm | 175mm | 175mm |
| Handlebar Width | 380mm | 400mm | 420mm | 420mm | 440mm | 440mm |
| Stem Length | 80mm | 90mm | 100mm | 100mm | 110mm | 110mm |
| Saddle Width | 155mm | 155mm | 143mm | 143mm | 143mm | 143mm |
| Seatpost Length | 300mm | 300mm | 360mm | 360mm | 360mm | 360mm |
| Stack | 514mm | 527mm | 544mm | 565mm | 591mm | 612mm |
| Reach | 375mm | 380mm | 384mm | 395mm | 402mm | 408mm |
| Head Tube Length | 109mm | 120mm | 137mm | 157mm | 184mm | 204mm |
| Head Tube Angle | 71.75° | 72.5° | 73° | 73.5° | 73.5° | 74° |
| BB Height | 266mm | 266mm | 268mm | 268mm | 268mm | 268mm |
| BB Drop | 74mm | 74mm | 72mm | 72mm | 72mm | 72mm |
| Trail | 63mm | 58mm | 58mm | 55mm | 55mm | 52mm |
| Fork Length, Full | 369mm | 369mm | 369mm | 369mm | 369mm | 369mm |
| Fork Rake/Offset | 47mm | 47mm | 44mm | 44mm | 44mm | 44mm |
| Front Center | 574mm | 577mm | 579mm | 591mm | 606mm | 613mm |
| Chainstay Length | 410mm | 410mm | 410mm | 410mm | 410mm | 410mm |
| Wheelbase | 973mm | 975mm | 978mm | 991mm | 1005mm | 1012mm |
| Top Tube Length, Horizontal | 508mm | 531mm | 540mm | 562mm | 577mm | 595mm |
| Bike Standover Height | 705mm | 728mm | 748mm | 769mm | 796mm | 824mm |
| Seat Tube Length | 431mm | 462mm | 481mm | 504mm | 532mm | 567mm |
| Seat Tube Angle | 75.5° | 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 needed3.
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.