Ridley Astr geometryGravel · 2027 · 5 sizes, from XS to XL
The Ridley Astr is a gravel bike available in 5 sizes, from XS to XL. Stack ranges from 536 to 619 mm and reach from 376 to 432 mm. Its geometry is low and long, with a racing fit. All sizes share 425 mm chainstays. Data from 2027; geometry from 2026 is also available.
What size Astr 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.
Enter your stack and reach to see which size fits you best.
Geometry chart by size
Measurements in mm and degrees, as published by Ridley. The ones that matter most for choosing a size are in bold.
| Size | XS | S | M | L | XL |
|---|---|---|---|---|---|
| Stack | 536 | 550 | 571 | 595 | 619 |
| Reach | 376 | 392 | 406 | 419 | 432 |
| Effective top tube | 525 | 550 | 570 | 590 | 615 |
| Head tube length | 115 | 130 | 150 | 175 | 200 |
| Head angle | 71.0° | 71.0° | 71.5° | 71.5° | 71.5° |
| Chainstay length | 425 | 425 | 425 | 425 | 425 |
| Wheelbase | 1,006 | 1,027 | 1,043 | 1,064 | 1,085 |
| BB drop | 75 | 75 | 75 | 75 | 75 |
| Seat tube (method not stated) | 475 | 500 | 520 | 550 | 575 |
| Seat angle (method not stated) | 74.5° | 74.0° | 74.0° | 74.0° | 73.5° |
Source: Ridley official website · data from 11 Nov 2026. Spot a mistake?
Stack and reach of every size
Higher means a taller front end; further right means a longer reach. The blue dot is your search.
Character of each size
Compared with other gravel bikes. Further right means more of that quality.
Bikes with similar geometry (size M)
The closest size of other gravel models, by stack and reach.
Frequently asked questions
What size Astr 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 536/376 mm in size XS to 619/432 mm in size XL). 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 Astr in size M?
Stack of 571 mm and reach of 406 mm, with an effective top tube of 570 mm and a head angle of 71.5°.
Is the Astr a racing or an endurance bike?
Racing. In size M its stack-to-reach ratio is at percentile 12 of gravel bikes: a low, stretched position.
Does it have the same geometry as the Astr RS?
In size M, yes: same stack and reach. If one already fits you, the same size of the other will put you in the same position.