2017 Trek Session DH 27.5 vs 2019 Specialized Demo Alloy 27.5
The LONG is the Specialized Demo Alloy 27.5 size closest to your L Trek Session 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 27.5
Compared with the Trek Session DH 27.5 in L, the Specialized Demo Alloy 27.5 in LONG places the top of the head tube 11 mm higher and 8 mm further forward, relative to the bottom bracket.
- Frame stack
- +11 mm
- Higher front end
- Frame reach
- +8 mm
- Longer frame reach
- Wheelbase
- −1 mm
- About the same
- 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 DH 27.5 numbers we have for size L are missing the seat angle. The numbers below still compare.
Geometry side by side
| Measurement | Trek Session DH 27.5 L | Specialized Demo Alloy 27.5 LONG | Difference |
|---|---|---|---|
| Reach | 432 | 440mm | +8 mm |
| Stack | 603 | 614mm | +11 mm |
| Head tube angle | 64.2° | 63.5° | −0.7° |
| Effective top tube | 614 | 616mm | +2 mm |
| Chainstay length | 443 | 430mm | −13 mm |
| Wheelbase | 1229 | 1228mm | −1 mm |
| BB drop | 9 | 12mm | +3 mm |
| BB height | 364 | 342mm | −22 mm |
| Standover | 790 | 698mm | −92 mm |
| Seat tube length | 456 | 419mm | −37 mm |
| Head tube length | 115 | 105mm | −10 mm |
| Seat tube angle | not listed | 74° |
Differences are the Specialized Demo Alloy 27.5 minus the Trek Session DH 27.5. Full charts: 2017 Trek Session DH 27.5, 2019 Specialized Demo Alloy 27.5.
Where each sits in its class
Trek Session DH 27.5Specialized Demo Alloy 27.5
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 DH 27.588 DH 27.5 | Specialized Demo Alloy 27.5Alloy 27.5 |
|---|---|---|
| Frame | Trek Alpha Platinum | not listed |
| Fork | RockShox BoXXer RC | RockShox BoXXer RC 27.5 |
| Shifter | SRAM X0 DH | SRAM GX |
| Derailleur | SRAM X01 | SRAM GX |
| Cassette | SRAM GX DH | SRAM PG-1030 |
| Chain | SRAM PC1110 | SRAM PC-1031 |
| Crankset | TruVativ Descendant | SRAM Descendant |
| Pedals | Wellgo MG-1 | not listed |
| Wheelset | DT Swiss FR2150 | not listed |
| Tire | Bontrager G4 Team Issue | Specialized Butcher |
| Brake | SRAM Code R | SRAM Guide RE |
| Handlebar | Bontrager Line | not listed |
| Stem | Race Face Chester | Specialized two-piece |
| Headset | FSA Orbit | not listed |
| Seatpost | Bontrager Rhythm Elite | not listed |
| Saddle | Bontrager Evoke 2 | Specialized Phenom Comp |
| Rear shock | not listed | Fox Van RC |
| Grips | not listed | Specialized Sip Grip |
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