Trek Session geometryMTB · 2022 · 3 sizes, from R1 to R3
The Trek Session is a mtb bike available in 3 sizes, from R1 to R3. Stack ranges from 634 to 634 mm and reach from 447 to 499 mm. Its geometry is low and long, with a racing fit.
What size Session 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 Trek. The ones that matter most for choosing a size are in bold.
| Size | R1 | R2 | R3 |
|---|---|---|---|
| Stack | 634 | 634 | 634 |
| Reach | 447 | 472 | 499 |
| Effective top tube | 586 | 617 | 652 |
| Head tube length | 117 | 117 | 117 |
| Head angle | 63.6° | 63.6° | 63.6° |
| Effective seat angle | 77.1° | 77.1° | 77.1° |
| Actual seat angle | 61.6° | 61.6° | 61.6° |
| Chainstay length | 435 | 441 | 448 |
| Wheelbase | 1,243 | 1,274 | 1,309 |
| BB drop | 12 | 12 | 12 |
| BB height | 359 | 359 | 359 |
| Fork offset | 46 | 46 | 46 |
| Trail | 131 | 131 | 132 |
| Standover | 755 | 759 | 757 |
| Seat tube (method not stated) | 425 | 425 | 425 |
Source: Trek 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 mtb bikes. Further right means more of that quality.
Bikes with similar geometry (size R2)
The closest size of other mtb models, by stack and reach.
Frequently asked questions
What size Session 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 634/447 mm in size R1 to 634/499 mm in size R3). 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 Session in size R2?
Stack of 634 mm and reach of 472 mm, with an effective top tube of 617 mm and a head angle of 63.6°.
Is the Session a racing or an endurance bike?
Racing. In size R2 its stack-to-reach ratio is at percentile 33 of mtb bikes: a low, stretched position.