2021 Trek Session AL 27.5 Frameset vs 2023 Trek Session C 27.5 Frameset
The S is the Trek Session C 27.5 Frameset size closest to your M Trek Session AL 27.5 Frameset. We match frame stack and reach. This is a geometry comparison, not a fit recommendation; stem, spacers, handlebars and saddle setup also affect your riding position.
What changes on the Trek Session C 27.5 Frameset
Compared with the Trek Session AL 27.5 Frameset in M, the Trek Session C 27.5 Frameset in S places the top of the head tube 13 mm higher and about as far forward, relative to the bottom bracket. Its wheelbase is 11 mm longer, which can contribute to stability at speed.
- Frame stack
- +13 mm
- Higher front end
- Frame reach
- +2 mm
- About the same reach
- Wheelbase
- +11 mm
- Longer: steadier at speed
- Head angle
- −0.7°
- Slacker: calmer steering
- Chainstays
- +2 mm
- About the same
The two frames
We can't draw these frames yet. The Trek Session AL 27.5 Frameset numbers we have for size M are missing the seat angle. The numbers below still compare.
Geometry side by side
| Measurement | Trek Session AL 27.5 Frameset M | Trek Session C 27.5 Frameset S | Difference |
|---|---|---|---|
| Reach | 408 | 410 | +2 mm |
| Stack | 603 | 616 | +13 mm |
| Head tube angle | 64.2° | 63.5° | −0.7° |
| Effective top tube | 590 | 579 | −11 mm |
| Chainstay length | 443 | 445 | +2 mm |
| Wheelbase | 1205 | 1216 | +11 mm |
| BB drop | 9 | 20 | +11 mm |
| BB height | 364 | 356 | −8 mm |
| Standover | 793 | 738 | −55 mm |
| Seat tube length | 426 | 425 | −1 mm |
| Head tube length | 115 | 115 | ±0 mm |
Differences are the Trek Session C 27.5 Frameset minus the Trek Session AL 27.5 Frameset. Full charts: 2021 Trek Session AL 27.5 Frameset, 2023 Trek Session C 27.5 Frameset.
Where each sits in its class
Trek Session AL 27.5 FramesetTrek Session C 27.5 Frameset
Each bike is ranked against the other downhill bikes on Quiver, on frame geometry alone. Not your hand position or ride feel.
What each ships with
The stock build of each bike's first listed trim. Parts that match are dimmed.
| Part | Trek Session AL 27.5 FramesetAL 27.5 Frameset | Trek Session C 27.5 Frameset27.5 Frameset |
|---|---|---|
| Frame | Trek Alpha Platinum | Trek OCLV |
| Headset | FSA Orbit | FSA Orbit |
Know what is on every bike.
Add your bike to Quiver. Keep its parts, setup, and service history together, then share your build.
Explore the app
