Polygon Siskiu T8 bike fit and size guide

Review the published geometry for the 2026 Polygon Siskiu T8, compare supported sizes, and open the TrainCraft calculator with this bike preselected.

Supported sizes

S, M, L, XL

Family

cross-country geometry

This bike is tuned around efficient climbing, technical handling, and a compact off-road cockpit.

What to compare

Stack, reach, setup

Use this guide to compare stack, reach, and XC cockpit assumptions before choosing a frame size.

Open calculator with Polygon Siskiu T8 Open generic bike fit tool View original geometry source

Geometry and size breakdown

The calculator button opens the bike step with this model and size already selected. Then enter rider measurements and run the fit report.

Size	Stack	Reach	Top tube	Head tube	Stem	Crank	Fit calculator
S	604 mm	440 mm	568 mm	89 mm	45 mm	170 mm	Use in calculator
M	609 mm	465 mm	595 mm	95 mm	45 mm	170 mm	Use in calculator
L	622 mm	485 mm	619 mm	110 mm	50 mm	175 mm	Use in calculator
XL	636 mm	505 mm	644 mm	125 mm	50 mm	175 mm	Use in calculator

How to use this guide

Start with the size table to narrow the geometry range you actually want. Then open the calculator to compare that geometry against your body dimensions, flexibility, and fit priorities.

The TrainCraft bike fit tool models saddle height, cockpit reach, and bar drop using the frame geometry plus stock cockpit assumptions for the Polygon Siskiu T8.

That is more useful than a generic height chart because two sizes can both fit your height while requiring very different stems, spacers, or saddle positions.

FAQ

What sizes are available for the Polygon Siskiu T8?

TrainCraft currently tracks these Polygon Siskiu T8 sizes: S, M, L, XL. The calculator uses each size's published geometry and stock cockpit assumptions to compare fit outcomes.

Can I use the TrainCraft calculator for Polygon Siskiu T8 sizing?

Yes. Open the calculator from this page to preload the Polygon Siskiu T8, then compare sizes against your body measurements, fit priorities, flexibility, and riding posture preferences.

What should I compare on the Polygon Siskiu T8 before picking a size?

Start with stack, reach, effective top tube, and the stock stem/crank setup. TrainCraft uses those numbers to estimate cockpit reach, bar drop, saddle position, and how much adjustment headroom each size leaves.