2019 Specialized Demo Expert 29 vs 2021 Trek Session C 27.5 Frameset
The XL is the Trek Session C 27.5 Frameset size closest to your S4 Specialized Demo Expert 29. 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 Expert 29 in S4, the Trek Session C 27.5 Frameset in XL places the top of the head tube 17 mm lower and 10 mm further forward, relative to the bottom bracket. Its wheelbase is 10 mm shorter, which can contribute to quicker direction changes.
- Frame stack
- −17 mm
- Lower front end
- Frame reach
- +10 mm
- Longer frame reach
- Wheelbase
- −10 mm
- Shorter: quicker to change direction
- Head angle
- +0.8°
- Steeper: sharper steering
- Chainstays
- −5 mm
- Shorter: livelier
The two frames
Only the Specialized Demo Expert 29 is drawn. The Trek Session C 27.5 Frameset numbers we have for size XL are missing the seat angle.
Geometry side by side
| Measurement | Specialized Demo Expert 29 S4 | Trek Session C 27.5 Frameset XL | Difference |
|---|---|---|---|
| Reach | 465mm | 475 | +10 mm |
| Stack | 633mm | 616 | −17 mm |
| Head tube angle | 62.7° | 63.5° | +0.8° |
| Seat tube angle | 76.3° | not listed | |
| Effective top tube | 620mm | 631 | +11 mm |
| Chainstay length | 450mm | 445 | −5 mm |
| Wheelbase | 1291mm | 1281 | −10 mm |
| BB drop | 25mm | 20 | −5 mm |
| BB height | 350mm | 356 | +6 mm |
| Standover | 760mm | 748 | −12 mm |
| Seat tube length | 420mm | 456 | +36 mm |
| Head tube length | 105mm | 115 | +10 mm |
Differences are the Trek Session C 27.5 Frameset minus the Specialized Demo Expert 29. Full charts: 2019 Specialized Demo Expert 29, 2021 Trek Session C 27.5 Frameset.
Where each sits in its class
Specialized Demo Expert 29Trek 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 Expert 29Expert 29 | Trek Session C 27.5 Frameset27.5 Frameset |
|---|---|---|
| Fork | RockShox BoXXer RC 29 | not listed |
| Rear shock | RockShox Super Deluxe RC World | not listed |
| Shifter | SRAM GX | not listed |
| Derailleur | SRAM GX | not listed |
| Cassette | SRAM PG-1030 | not listed |
| Chain | SRAM PC-1031 | not listed |
| Crankset | SRAM Descendant | not listed |
| Tire | Specialized Butcher BLCK DMND | not listed |
| Brake | SRAM Code R | not listed |
| Stem | Specialized two-piece | not listed |
| Grips | Specialized Sip Grip | not listed |
| Saddle | Specialized Henge DH | not listed |
| Frame | not listed | Trek OCLV |
| Headset | not listed | FSA Orbit |
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