The Polygon Siskiu T7 29 is an entry-level mountain bike engineered to balance high-speed control with playful handling, while not putting too big a dent in your wallet. Aimed for tackling trail riding and getting a little rowdy, the Siskiu features modern geometry and clever spec choices. As a result, it delivers plenty of thrills on the trails.
Polygon Siskiu T7 29 frame and suspension
Up front, there’s a RockShox Recon Silver RL fork with 140mm travel. At the heart of the Siskiu T7 29 is the hydroformed 6061 aluminium frame. Its chunky tubes, neat welds and clean design lines make it feel like a much more expensive bike. This 29er version dishes out 135mm of rear travel from a linkage-driven single-pivot suspension platform, where the seatstays drive the rear shock. This design has been very successful on bikes such as the Commencal Meta series. It enables Polygon to tune the leverage rate to make the suspension more progressive.
The seatstays are connected to the seat tube by a one-piece rocker, providing lateral rigidity and decreasing side-loading on the shock. It also helps control the leverage rate. The frame features semi-internal cable routing through the down tube, but has external routing along the chainstays. The chainstays splay out to fit Boost 12x148mm bolt-thru rear-hub spacing, which is now a common standard and means upgrades to wheels will be easy.
There’s routing for ad dropper post cable, which we would expect on a bike of this price. The head tube features a tapered design with ZS 44 (Zero Stack) upper and ZS 56 lower bearing sizes that feature on more expensive bikes and will allow for fork upgrades. The bottom bracket is a user-friendly BSA threaded 73mm shell that should help the home mechanics. The rear disc-brake mount is 160mm, but the frame can take a 180mm rotor.
While protecting the frame, the rubber also silences chain slap. Polygon has fitted good frame protection on the chainstay, which is a nice touch. Plus, there’s space for a water bottle inside the front triangle.
Polygon Siskiu T7 29 geometry
The Siskiu T7 geometry is modern and reflective of more expensive bikes. However, this is one of the reasons why it’s so much fun to ride on the trail. I tested a size-medium frame. This comes with a well-proportioned 460mm reach and snappy 430mm chainstays, which give the bike a playful feel to its handling. The head tube angle is a versatile 65.5 degrees and the frame has a pedal-friendly 76.5-degree effective seat tube angle. These measurements give a 606mm effective top tube, sitting you comfortably upright when pedalling seated.
The bike is low-slung with a 335mm bottom-bracket height from its aggressive 39mm bottom-bracket drop. The seat tube is short at 400mm, meaning the bike can take advantage of longer dropper posts. The stack is also relatively low at 608mm. That means you can run the bars low for an aggressive over-the-front riding position or run plenty of spacers under the stem to give more confidence on the descents.
|Wheel size (in)||27.5||27.5||29||29||29|
|Seat angle (degrees)||76.5||76.5||76.5||76.5||76.5|
|Head angle (degrees)||65||65||65.5||65.5||65.5|
|Seat tube (mm)||385||400||400||415||430|
|Top tube (mm)||582.5||605.7||605.9||629.1||652.4|
|Head tube (mm)||105||120||90||105||120|
|Bottom bracket height (mm)||335||335||335||335||335|
Polygon Siskiu T7 29 specifications
The RockShox Deluxe Select+ is tuned specifically for the frame. The Polygon comes with all the features you’d find on high-end bikes, including adjustable suspension, a dropper post, wide-range 1x gears and wide handlebars paired with a short stem. The Siskiu T7 uses a RockShox Deluxe Select+ shock tuned for the frame. This features RockShox’s DebonAir+ spring, external low-speed rebound adjustment and a two-position compression adjuster.
The RockShox Recon Silver RL is a solid performer. Up-front there’s a RockShox Recon Silver RL fork with 140mm travel. This uses RockShox’s Solo Air spring and Motion Control damper with externally adjustable low-speed rebound and compression damping. Impressively, you get 1×12 gearing. This is taken care of by Shimano’s Deore M6100 range, including its wide-range 10-51 tooth cassette.
Stopping power comes from Tektro’s HD-M735 brakes, with a four-piston front caliper and two-piston rear caliper. These use Shimano 180mm CentreLock rotors. The Siskiu T7 rolls on Entity XL 2 Disc wheels with a 35mm internal rim width suited to wider mountain bike tyres. My test bike was fitted with the aggressive Vee Flow Snap Tacky in a wide 29×2.6in size, although the website shows Schwalbe Hans Dampf tyres.
The Polyygon’s geometry allows room for longer travel dropper posts. Finishing kit includes a 150mm Tranz-X dropper and Entity Xtend saddle, with a 780mm-wide Entity Xpert handlebar and short 35mm-reach Entity Xpert stem that highlights its intentions as a rowdy trail ripper. The bike tips the scales at 16.14kg.
Polygon Siskiu T7 29 ride impressions
The bike was subjected to a thorough and varied thrashing. I tested the Polygon on a mix of blue and red trail-centre loops, off-piste descents around the Forest of Dean, and laps of technical flow lines at Bike Park Wales to give it a thorough thrashing through the range of riding it will be subjected to.
I set up the rear suspension with 25 per cent sag, which was 159psi for 76kg. The rebound damping is very firm, so I ran it at nine clicks from closed, out of 10. I set the forks at 65psi, which was about 20psi below RockShox’s recommended pressure for my weight. That resulted in around 20 per cent sag, which gave them enough support for my tastes. Compression was set wide open and rebound five or six clicks from closed.
Polygon Siskiu T7 29 climbing performance
The Siskiu climbs on par with its peers. Climbing on the Siskiu T7 is a mixed bag. Its upright position and sticky tyres have traits of an enduro bike, yet it’s more efficient to pedal like a trail bike. The steep effective seat tube angle put me in an advantageous position to generate a strong pedal stroke when needed to grind up short, steep pitches. In addition, the short chainstays helped keep weight on the rear tyre so I could find traction, which there was plenty of from the grippy Vee tyres. When the trail got steep, I needed to actively lean over the front to help the front end track and keep balance between the wheels, but this wasn’t a chore.
On mellower climbs, the short effective top tube makes climbing comfortable, meaning longer slogs don’t stretch you into contorted positions. It’s not particularly racey, but if needed, you can alter the bar height with the stem spacers. The suspension does an admirable balancing act of keeping the rear end active to absorb bumps, roots and rocks in the trail, while not sinking into its travel to rob you of power. I could ride with the shock in its open setting comfortably on most climbs and not feel as though the bike was hindering me. On awkward trail-centre hairpin turns, the Siskiu T7, with its agile handling, made light work of them, not needing many body movements to maintain balance or control.
The Polygon is booted with Veetireco’s Flow Snap tyres with a 2.6in width. With its burly tyres, the Polygon isn’t the fastest or most efficient uphill. Still, it gets the job done comfortably and without fuss.
Shimano’s Deore 1×12 drivetrain is a nice feature at this entry-point. The 1×12 Shimano Deore gears are a great addition and mean you can ride up whatever you come across. These worked well when changing gears under load and offered a nice, smooth pedal stroke without any frustrating grinding.
Polygon Siskiu T7 29 descending performance
It’s a playful ride that responds well to being thrown around. Once at the top of the hill, the Polygon is a capable piece of kit with an impressive mix of sorted geometry and decent components. On flowing terrain, you can get up to speed quickly. The Polygon isn’t a sluggish bike and doesn’t waste its travel when you’re pedalling hard. Still, it helps to keep putting effort in to overcome the grippy tyres.
Its short chainstays and 65.5-degree head tube angle, blended with the 35mm stem length, deliver a nippy bike through weaving sections of trail, where you can duck and dive around trees full of confidence. The 460mm reach gave me space to find a well-balanced position on the bike without having to move around a lot to hunt out traction.
Polygon has created a bike that responds well on a variety of terrain. Through the corners, the Polygon is easy to change direction on. Its low bottom bracket helps the bike feel planted, and I found it easy to lean from one side to the other, which helped link turns and maintain momentum on twisty trails. The bike has a playful character and appears to enjoy being thrown around. That said, its stability didn’t have me worried that the bike was out of its depth when speeds picked up. The suspension on the Siskiu T7 is measured and offers a supportive ride that does a good job of soaking up the hits. Still, it doesn’t fully isolate the rider from rough trails. It gives feedback that some riders might enjoy and provides support in high-load turns and compressions, which helps its playful character.
Over rough trails, it’s good but not great. The forks are smooth and plush but do miss a progressive build-up of support and have a slight spike. However, they rebound quickly enough to recover from repeated hits, which helps keep the bike balanced. Polygon has done a great job of creating a versatile trail bike that has to tackle a wide variety of trails. The tyres limit its mile-munching ability, but make it thrive on the descents and give you plenty of confidence in variable conditions on mixed terrain.
A couple of changes and the Polygon could easily transform into a long-distance machine that pedals well and gives plenty of confidence when the trails get wild. One improvement I would make is fitting more powerful brakes and rotors that can handle metallic pads. Unfortunately, the brakes didn’t inspire the most confidence, with their long lever throw and only moderate power.
How does the Polygon Siskiu T7 29 compare to the Boardman MTR 8.8?
The Boardman MTR 8.8 is built to be the ideal all-round UK trail bike for riders looking to take things more seriously. The Polygon doesn’t win for ride feel on the trail; that belongs to the Boardman, with its impressively smooth ride character and competence. It also irons out small chatter and delivers better performance on rougher trails. It does have 10mm more travel front and rear, though.
Still, on paper for a trail bike, the Siskiu T7 trumps the MTR 8.8. Its 1×12 gearing, 12x148mm bolt-thru rear axle, and better dropper lever and brakes make up for any minor shortcomings on the trail. The frame is ripe for upgrades too. Yes, it’s more money, but the bike is more future-proof with nicer styling.
Polygon Siskiu T7 29 bottom line
The Polygon is a capable all-rounder. As a complete package, the Polygon is as impressive as it is fun to ride. Suppose you’re after a bike capable over a wide range of trails, from fairly benign blues to hitting jump lines in the bike park and tearing up natural tech trails. In that case, the Siskiu T7 delivers with its modern frame geometry, impressive spec list and potential for upgrades. It will take all you can throw at it and leave you with a smile from ear to ear. It won’t quite keep up with bikes twice its price in all-out speed, but you won’t enjoy riding it any less.