Ridley Omnium Fast geometryTime trial / Triathlon · 2025 · 3 sizes, from S to L
The Ridley Omnium Fast is a time trial / triathlon bike available in 3 sizes, from S to L. Stack ranges from 485 to 542 mm and reach from 409 to 460 mm. Its position sits between racing and endurance. All sizes share 380 mm chainstays.
What size Omnium Fast 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 | S | M | L |
|---|---|---|---|
| Stack | 485 | 514 | 542 |
| Reach | 409 | 428 | 460 |
| Effective top tube | 530 | 570 | 610 |
| Head tube length | 90 | 120 | 150 |
| Head angle | 74.0° | 74.0° | 74.0° |
| Chainstay length | 380 | 380 | 380 |
| Wheelbase | 955 | 982 | 1,022 |
| BB drop | 55 | 55 | 55 |
| Standover | 725 | 754 | 782 |
| Seat tube (method not stated) | 470 | 500 | 540 |
| Seat angle (method not stated) | 76.0° | 74.5° | 74.5° |
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 time trial / triathlon bikes. Further right means more of that quality.
Bikes with similar geometry (size M)
The closest size of other time trial / triathlon models, by stack and reach.
Frequently asked questions
What size Omnium Fast 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 485/409 mm in size S to 542/460 mm in size L). 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 Omnium Fast in size M?
Stack of 514 mm and reach of 428 mm, with an effective top tube of 570 mm and a head angle of 74.0°.
Is the Omnium Fast a racing or an endurance bike?
In between. In size M its stack-to-reach ratio is at percentile 38 of time trial / triathlon bikes: neither very low nor very tall.