2026 Forbidden Reya Tier vs 2026 Polygon Siskiu T T8 UDH

What changes on the Polygon Siskiu T T8 UDH

Compared with the Forbidden Reya Tier in S2, the Polygon Siskiu T T8 UDH in XL places the top of the head tube 24 mm higher and 50 mm further forward, relative to the bottom bracket. Its wheelbase is 63 mm longer, which can contribute to stability at speed.

Frame stack

+24 mm

Higher front end

Frame reach

+50 mm

Longer frame reach

Wheelbase

+63 mm

Longer: steadier at speed

Head angle

−0.5°

Slacker: calmer steering

Chainstays

n/a

One of the bikes has no number for this

The two frames

We can't draw these frames yet. The Forbidden Reya Tier numbers we have for size S2 are missing the chainstay length. The numbers below still compare.

Geometry side by side

Differences are the Polygon Siskiu T T8 UDH minus the Forbidden Reya Tier. Full charts: 2026 Forbidden Reya Tier, 2026 Polygon Siskiu T T8 UDH.

Where each sits in its class

Forbidden Reya TierPolygon Siskiu T T8 UDH

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.