2018 Specialized Demo 8 Frameset vs 2020 Trek Session AL 27.5 Frameset
The XL is the Trek Session AL 27.5 Frameset size closest to your EXTRA LONG Specialized Demo 8 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 AL 27.5 Frameset
Compared with the Specialized Demo 8 Frameset in EXTRA LONG, the Trek Session AL 27.5 Frameset in XL places the top of the head tube 11 mm lower and 4 mm further back, relative to the bottom bracket. Its wheelbase is 5 mm longer, which can contribute to stability at speed.
- Frame stack
- −11 mm
- Lower front end
- Frame reach
- −4 mm
- Shorter frame reach
- Wheelbase
- +5 mm
- Longer: steadier at speed
- Head angle
- +0.7°
- Steeper: sharper steering
- Chainstays
- +13 mm
- Longer: more planted
The two frames
Only the Specialized Demo 8 Frameset is drawn. The Trek Session AL 27.5 Frameset numbers we have for size XL are missing the seat angle.
Geometry side by side
| Measurement | Specialized Demo 8 Frameset EXTRA LONG | Trek Session AL 27.5 Frameset XL | Difference |
|---|---|---|---|
| Reach | 460mm | 456 | −4 mm |
| Stack | 614mm | 603 | −11 mm |
| Head tube angle | 63.5° | 64.2° | +0.7° |
| Seat tube angle | 74° | not listed | |
| Effective top tube | 636mm | 638 | +2 mm |
| Chainstay length | 430mm | 443 | +13 mm |
| Wheelbase | 1248mm | 1253 | +5 mm |
| BB drop | 12mm | 9 | −3 mm |
| BB height | 342mm | 364 | +22 mm |
| Standover | 698mm | 775 | +77 mm |
| Seat tube length | 367mm | 456 | +89 mm |
| Fork length | 590mm | not listed | |
| Head tube length | 105mm | 115 | +10 mm |
Differences are the Trek Session AL 27.5 Frameset minus the Specialized Demo 8 Frameset. Full charts: 2018 Specialized Demo 8 Frameset, 2020 Trek Session AL 27.5 Frameset.
Where each sits in its class
Specialized Demo 8 FramesetTrek Session AL 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 | Specialized Demo 8 FramesetS-Works Frameset | Trek Session AL 27.5 FramesetAL 27.5 Frameset |
|---|---|---|
| Rear shock | Öhlins TTX | not listed |
| Frame | not listed | Trek Alpha Platinum |
| Headset | not listed | FSA Orbit |
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