2017 Specialized Demo Alloy vs 2019 Trek Session C 27.5 Frameset
The S is the Trek Session C 27.5 Frameset size closest to your SHORT Specialized Demo Alloy. 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 Specialized Demo Alloy in SHORT, the Trek Session C 27.5 Frameset in S places the top of the head tube at about the same height and 15 mm further forward, relative to the bottom bracket. Its wheelbase is 33 mm longer, which can contribute to stability at speed.
- Frame stack
- +2 mm
- About the same height
- Frame reach
- +15 mm
- Longer frame reach
- Wheelbase
- +33 mm
- Longer: steadier at speed
- Head angle
- ±0.0°
- About the same head angle
- Chainstays
- +15 mm
- Longer: more planted
The two frames
Only the Specialized Demo Alloy is drawn. The Trek Session C 27.5 Frameset numbers we have for size S are missing the seat angle.
Geometry side by side
| Measurement | Specialized Demo Alloy SHORT | Trek Session C 27.5 Frameset S | Difference |
|---|---|---|---|
| Reach | 395mm | 410 | +15 mm |
| Stack | 614mm | 616 | +2 mm |
| Head tube angle | 63.5° | 63.5° | ±0.0° |
| Seat tube angle | 74° | not listed | |
| Effective top tube | 571mm | 579 | +8 mm |
| Chainstay length | 430mm | 445 | +15 mm |
| Wheelbase | 1183mm | 1216 | +33 mm |
| BB drop | 12mm | 20 | +8 mm |
| BB height | 342mm | 356 | +14 mm |
| Standover | 698mm | 738 | +40 mm |
| Seat tube length | 367mm | 425 | +58 mm |
| Head tube length | 105mm | 115 | +10 mm |
Differences are the Trek Session C 27.5 Frameset minus the Specialized Demo Alloy. Full charts: 2017 Specialized Demo Alloy, 2019 Trek Session C 27.5 Frameset.
Where each sits in its class
Specialized Demo AlloyTrek 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 | Specialized Demo Alloy8 Alloy | Trek Session C 27.5 Frameset27.5 Frameset |
|---|---|---|
| Rear shock | Öhlins TTX | not listed |
| Frame | not listed | Trek OCLV |
| Headset | not listed | FSA Orbit |
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