2015 Trek Session 9.9 DH 27.5 vs 2017 Specialized Demo Alloy
The M is the Specialized Demo Alloy size closest to your M Trek Session 9.9 DH 27.5. 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 Specialized Demo Alloy
Compared with the Trek Session 9.9 DH 27.5 in M, the Specialized Demo Alloy in M places the top of the head tube 11 mm higher and 12 mm further forward, relative to the bottom bracket. Its wheelbase is 3 mm longer, which can contribute to stability at speed.
- Frame stack
- +11 mm
- Higher front end
- Frame reach
- +12 mm
- Longer frame reach
- Wheelbase
- +3 mm
- Longer: steadier at speed
- Head angle
- −0.7°
- Slacker: calmer steering
- Chainstays
- −13 mm
- Shorter: livelier
The two frames
We can't draw these frames yet. The Trek Session 9.9 DH 27.5 numbers we have for size M are missing the seat angle. The numbers below still compare.
Geometry side by side
| Measurement | Trek Session 9.9 DH 27.5 M | Specialized Demo Alloy M | Difference |
|---|---|---|---|
| Reach | 408 | 420mm | +12 mm |
| Stack | 603 | 614mm | +11 mm |
| Head tube angle | 64.2° | 63.5° | −0.7° |
| Effective top tube | 590 | 596mm | +6 mm |
| Chainstay length | 443 | 430mm | −13 mm |
| Wheelbase | 1205 | 1208mm | +3 mm |
| BB drop | 14 | 12mm | −2 mm |
| BB height | 364 | 342mm | −22 mm |
| Standover | 793 | 698mm | −95 mm |
| Seat tube length | 390 | 367mm | −23 mm |
| Head tube length | 115 | 105mm | −10 mm |
| Seat tube angle | not listed | 74° |
Differences are the Specialized Demo Alloy minus the Trek Session 9.9 DH 27.5. Full charts: 2015 Trek Session 9.9 DH 27.5, 2017 Specialized Demo Alloy.
Where each sits in its class
Trek Session 9.9 DH 27.5Specialized Demo Alloy
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 9.9 DH 27.59.9 DH 27.5 | Specialized Demo Alloy8 Alloy |
|---|---|---|
| Frame | Trek OCLV | not listed |
| Fork | Fox Factory | not listed |
| Shifter | Shimano Saint | not listed |
| Derailleur | Shimano Saint | not listed |
| Cassette | Shimano Ultegra | not listed |
| Chain | Shimano XTR | not listed |
| Crankset | Shimano Saint | not listed |
| Pedals | Wellgo MG-1 | not listed |
| Wheelset | DT Swiss FR1950 Gravity Classic | not listed |
| Tire | Bontrager G4 Team Issue | not listed |
| Brake | Shimano Saint | not listed |
| Handlebar | Bontrager Rhythm | not listed |
| Stem | Bontrager Rhythm | not listed |
| Headset | Cane Creek IS-3 | not listed |
| Seatpost | Bontrager Rhythm Elite | not listed |
| Saddle | Bontrager Evoke 3 | not listed |
| Rear shock | not listed | Öhlins TTX |
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