2026 Polygon Siskiu T T8 UDH vs 2026 Forbidden Reya Tier
The S2 is the Forbidden Reya Tier size closest to your M Polygon Siskiu T T8 UDH. 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 Forbidden Reya Tier
Compared with the Polygon Siskiu T T8 UDH in M, the Forbidden Reya Tier in S2 places the top of the head tube 3 mm higher and 10 mm further back, relative to the bottom bracket. Its wheelbase is 10 mm shorter, which can contribute to quicker direction changes.
- Frame stack
- +3 mm
- Higher front end
- Frame reach
- −10 mm
- Shorter frame reach
- Wheelbase
- −10 mm
- Shorter: quicker to change direction
- Head angle
- +0.5°
- Steeper: sharper steering
- Chainstays
- n/a
- One of the bikes has no number for this
The two frames
Only the Polygon Siskiu T T8 UDH is drawn. The Forbidden Reya Tier numbers we have for size S2 are missing the chainstay length.
Geometry side by side
| Measurement | Polygon Siskiu T T8 UDH M | Forbidden Reya Tier S2 | Difference |
|---|---|---|---|
| Reach | 465 | 455 | −10 mm |
| Stack | 609 | 612 | +3 mm |
| Head tube angle | 64.5 | 65.0 | +0.5° |
| Seat tube angle | 71.2 | 71.3 | +0.1° |
| Effective top tube | 595 | 596 | +1 mm |
| Chainstay length | 430 | not listed | |
| Wheelbase | 1214 | 1204 | −10 mm |
| BB height | 337.5 | 331 | −7 mm |
| Standover | 705 | 717 | +12 mm |
| Seat tube length | 400 | 420 | +20 mm |
| Head tube length | 95 | 105 | +10 mm |
| Fork length | not listed | 541 |
Differences are the Forbidden Reya Tier minus the Polygon Siskiu T T8 UDH. Full charts: 2026 Polygon Siskiu T T8 UDH, 2026 Forbidden Reya Tier.
Where each sits in its class
Polygon Siskiu T T8 UDHForbidden Reya Tier
Each bike is ranked against the other trail 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 | Polygon Siskiu T T8 UDHT8 with UDH | Forbidden Reya TierTier 1 |
|---|---|---|
| Frame | Polygon ALX Trail | Forbidden Reya |
| Fork | Fox 34 Performance | Fox 34 Factory SL |
| Rear shock | Fox Float | Fox Float Factory |
| Shifter | Shimano SLX M7100 | SRAM Pod Rocker Controller |
| Derailleur | Shimano SLX M7100 | SRAM XX XX SL |
| Cassette | Shimano SLX M7100 | SRAM XX SL Eagle Transmission |
| Chain | KMC X-12 | SRAM XX SL |
| Crankset | Shimano Deore M6120 | SRAM XX SL |
| Wheelset | Polygon MT6 | not listed |
| Tire | Maxxis Dissector | Maxxis Rekon Race |
| Brake | Shimano Deore M4100 | SRAM Motive Ultimate |
| Rotor | Shimano SM-RT54 | SRAM HS2 |
| Handlebar | Polygon EXPERT | OneUp Components Carbon |
| Stem | Polygon EXPERT | BikeYoke Barkeeper Stem |
| Headset | FSA No 57E | Cane Creek 40 |
| Dropper post | X-Fusion MANIC LC | OneUp Components V3 Dropper Post |
| Saddle | Linc XTENT | fizik Terra Ridon X1 |
| Chainring | not listed | SRAM 32T |
| Bottom bracket | not listed | SRAM DUB |
| Battery | not listed | SRAM AXS EP Powerpack |
| Hub | not listed | DT Swiss 240 SPLINE, DT Swiss 240 SPLINE Ratchet EXP |
| Rim | not listed | DT Swiss 1500 |
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