Construction and Features
Siskiu frames are beautifully welded, with most of the tube junctions smoothed using a second-pass technique that is usually reserved for high-end aluminum and titanium construction. Stand-over clearance is maximized with a dramatically sloping top tube - a feature that also enables short-legged riders to take advantage of longer-stroke dropper posts (the medium sized T-8 rocks a 150-millimeter Tranz-X). Stand-over is 30 inches (76 cm) at the center of the top tube, which is good for a 140-millimeter-travel 29er.
Most 29er dual-suspension frames offset the seat tube in order to clear the larger wheel at full compression. Polygon follows this design trend, the upside of which is that the chainstays can be shortened. The downside, however, is that raising the saddle positions taller riders farther back over the rear wheel, which is the opposite direction of where their weight distribution should be going. None of that should prove troublesome, though, if you are properly sized for the bike.
Under-appreciated as it is well proven, Polygon's single-pivot swingarm hinges at the top of the bike's 32-tooth chainring, where it can produce ample anti-squat when its rider needs it most (while struggling uphill in the larger cassette cogs), while minimizing pedal kickback throughout the suspension's range of compression. There is plenty of room in the rear triangle to fit larger tires than its 2.3 inch Nobby Nics, and while we are on the subject of big wheels, large clevis pivots at the rear dropouts, assisted by a sturdy one-piece wrap-around seat stay and a forged rocker link, ensure that the rear of the bike will not flex when push comes to shove.
Tradition dictates internal cable and hose routing, and the Siskiu reluctantly obliges, drawing a line in the sand with an externally routed rear brake hose that will pay dividends to any home mechanic who has to replace a brake and lacks the time or skills to sever a hose and re-bleed the system.
Tucked near the threaded bottom bracket shell are ISCG 05 mounts, which I'd expect on this well-appointed frame, but one detail that Polygon missed was a provision for a water bottle on the down tube. That's not a deal-breaker for me, however, so I'll leave it to someone else to call them out for that faux pasTwo Wheel Size Options
Polygon hails from Indonesia and its off-road range sells quite well in Asia, where there is a large demand for small-sized frames. To capture their home market, Polygon offers small and medium-sized Siskiu models with 27.5-inch wheels.
The 29 versions that we feature here begin with a medium-sized option and run up to extra large. Their specifications are very similar, although the smaller-wheel bikes enjoy more suspension travel and are booted up with wider tires. Interested? You can compare the two here