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The Beta Tests

The Beta Tests: Polygon Siskiu T8

Possibly the best $2,500 bike we've ever ridden.


-Awesome entry-level full-suspension mountain bike
-135 rear suspension travel (140 on 27.5″ wheel options)
-140mm front travel (150mm on 27.5″ wheel options)
-Aluminum frame


-Fully capable, modern trail bike geometry
-Excellent parts spec for the price
-Internal cable routing


-Resin-only brake rotors create weak braking
-Suspension platform isn’t very sophisticated





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Ask anyone who’s been riding a while what you need to spend to get a legit full-suspension mountain bike and they’ll likely tell you that you should spend at least three grand. But that was before the Polygon Siskiu T8 existed. Seriously, this has got to be the best $2,500 bike we’ve tested to date.

It’s not just the fact that the Siskiu T8 comes with a great parts spec, with a mostly Shimano SLX drivetrain, Fox suspension and 4-piston brakes. Nor is it just that it uses modern high-end standards like Boost 148mm rear and 110mm front spacing and a Micro Spline freehub body, making the Siskiu compatible with modern parts, and upgradeable as well. What really makes the Siskiu special are those things combined with the fact that this bike has very good geometry numbers.

You can bolt nice parts to any old thing and call it a budget bike. In fact, that’s what several brands do. They take an outdated model from years past, slap some modern parts on it, and call it good. Which would be just fine if mountain bike geometry didn’t change so dang fast. The trend of building mountain bike frames with longer front ends, slacker head angles, and steeper seat angles has been happening for a while, but has really ramped up in the last five years or so.

These changes make a massive difference in how bikes behave on the trail, such as how stable they are to descend on, and how efficiently they climb, regardless of the suspension platform and componentry on the them. Sure, nice parts make a difference, but good geometry is more important. I’d rather have a new, modern frame with outdated parts than an old frame with new parts—which is what you’re getting with many of the other bikes in this price range.

The Siskiu has progressive geometry numbers such as a 480mm reach on the size large, 76.5-degree seat tube angle, 65.5-degree head angle and short 430mm chainstays (425mm for 27.5″ wheels)—all comparable to those found on the most popular trail bikes in the world. It comes in 4 sizes, with 5 actual options. Size small rolls on 27.5″ wheels, size medium is available with 27.5″ or 29″ hoops, and sizes large and XL are 29er-only. The 29er sports 135mm of rear wheel travel and 140mm up front, while the 27.5″ options wisely run a little more travel, with 140mm out back and 150mm on the front.

Polygon uses a proven linkage-driven single pivot for the rear suspension, similar to what Kona uses for its full-suspension designs. It’s not the most sophisticated, but it’s reliable and uncomplicated, and perfect for a bike like the Siskiu. The steep seat angle allows the rider to keep weight forward, making the bike feel efficient while climbing. But, the suspension is pretty active on this bike, and does benefit from the shock’s lockout lever. And since the shock is mounted horizontally below the top tube, the lever is easily reached. Our testers found that the bike would make steep punchy climbs just fine with the shock open, but for any extended climbing we preferred firming it up a bit.

When it comes to handling and descending, the Siskiu will hold its own against bikes that are twice, even three times the price. Advanced riders will probably want to add some volume spacers to make the suspension more progressive, but the active, plush stock tune is great for anyone who’s learning. The long reach and relatively slack head angle create a stable, confident descender, and the medium amount of travel allows the bike to perform well in most conditions without feeling like either too much or too little.

We’re incredibly impressed with Polygon for offering the Siskiu T8, a genuinely shreddable bike, for well under the 3K mark. If you’re new to riding, on a budget, or you just want a great value, the Siskiu is really worth looking at. But, even though the Siskiu is a great buy, we feel obliged to say that a bike like the Ibis Ripley AF, starting at $3,200 and featuring sophisticated dw-link suspension, is worth the upgrade if the budget allows.

Studio photos: Ryan Palmer

Action photos: Anthony Smith and Paris Gore