mountain bikecross-country geometry2026

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
4
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.

Geometry and size breakdown

Every size links back into the calculator so you can compare the Polygon Siskiu T8 against your rider measurements instead of picking by height alone.

SizeStackReachTop tubeHead tubeStemCrankCalculator
S604 mm440 mm568 mm89 mm45 mm170 mmOpen size
M609 mm465 mm595 mm95 mm45 mm170 mmOpen size
L622 mm485 mm619 mm110 mm50 mm175 mmOpen size
XL636 mm505 mm644 mm125 mm50 mm175 mmOpen size

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.

Related mountain bike guides

Use nearby model pages to compare positioning trends before choosing between similar bikes.