2026 Polygon Siskiu T T8 UDH vs 2025 Trek Fuel EX

What changes on the Trek Fuel EX

Compared with the Polygon Siskiu T T8 UDH in M, the Trek Fuel EX in XXL places the top of the head tube 39 mm higher and 80 mm further forward, relative to the bottom bracket. Its wheelbase is 109 mm longer, which can contribute to stability at speed.

Frame stack

+39 mm

Higher front end

Frame reach

+80 mm

Longer frame reach

Wheelbase

+109 mm

Longer: steadier at speed

Head angle

±0.0°

About the same head angle

Chainstays

+20 mm

Longer: more planted

The two frames

Only the Polygon Siskiu T T8 UDH is drawn. The Trek Fuel EX numbers we have for size XXL are missing the seat angle.

Geometry side by side

Differences are the Trek Fuel EX minus the Polygon Siskiu T T8 UDH. Full charts: 2026 Polygon Siskiu T T8 UDH, 2025 Trek Fuel EX.

Where each sits in its class

Polygon Siskiu T T8 UDHTrek Fuel EX

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.