2018 Trek Session C 27.5 Frameset vs 2019 Specialized Demo Expert 29
The S4 is the Specialized Demo Expert 29 size closest to your XL Trek Session C 27.5 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 Specialized Demo Expert 29
Compared with the Trek Session C 27.5 Frameset in XL, the Specialized Demo Expert 29 in S4 places the top of the head tube 17 mm higher and 10 mm further back, relative to the bottom bracket. Its wheelbase is 10 mm longer, which can contribute to stability at speed.
- Frame stack
- +17 mm
- Higher front end
- Frame reach
- −10 mm
- Shorter frame reach
- Wheelbase
- +10 mm
- Longer: steadier at speed
- Head angle
- −0.8°
- Slacker: calmer steering
- Chainstays
- +5 mm
- Longer: more planted
The two frames
We can't draw these frames yet. The Trek Session C 27.5 Frameset numbers we have for size XL are missing the seat angle. The numbers below still compare.
Geometry side by side
| Measurement | Trek Session C 27.5 Frameset XL | Specialized Demo Expert 29 S4 | Difference |
|---|---|---|---|
| Reach | 475 | 465mm | −10 mm |
| Stack | 616 | 633mm | +17 mm |
| Head tube angle | 63.5° | 62.7° | −0.8° |
| Effective top tube | 631 | 620mm | −11 mm |
| Chainstay length | 445 | 450mm | +5 mm |
| Wheelbase | 1281 | 1291mm | +10 mm |
| BB drop | 20 | 25mm | +5 mm |
| BB height | 356 | 350mm | −6 mm |
| Standover | 748 | 760mm | +12 mm |
| Seat tube length | 456 | 420mm | −36 mm |
| Head tube length | 115 | 105mm | −10 mm |
| Seat tube angle | not listed | 76.3° |
Differences are the Specialized Demo Expert 29 minus the Trek Session C 27.5 Frameset. Full charts: 2018 Trek Session C 27.5 Frameset, 2019 Specialized Demo Expert 29.
Where each sits in its class
Trek Session C 27.5 FramesetSpecialized Demo Expert 29
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 C 27.5 Frameset27.5 Frameset | Specialized Demo Expert 29Expert 29 |
|---|---|---|
| Frame | Trek OCLV | not listed |
| Headset | FSA Orbit | not listed |
| Fork | not listed | RockShox BoXXer RC 29 |
| Rear shock | not listed | RockShox Super Deluxe RC World |
| Shifter | not listed | SRAM GX |
| Derailleur | not listed | SRAM GX |
| Cassette | not listed | SRAM PG-1030 |
| Chain | not listed | SRAM PC-1031 |
| Crankset | not listed | SRAM Descendant |
| Tire | not listed | Specialized Butcher BLCK DMND |
| Brake | not listed | SRAM Code R |
| Stem | not listed | Specialized two-piece |
| Grips | not listed | Specialized Sip Grip |
| Saddle | not listed | Specialized Henge DH |
Know what is on every bike.
Add your bike to Quiver. Keep its parts, setup, and service history together, then share your build.
Explore the app
