Polygon's Updated Siskiu T Proves That You Don't Have To Spend the Earth To Get a Very Capable Trail Bike
Wil Reviews The 2021 Polygon Siskiu T8
Updated with a new frame, refreshed geometry and refined suspension kinematics for 2021, the latest Siskiu T continues to carry the torch for Polygon as the brand’s wildly popular trail bike. Sitting in between the Siskiu D (XC) and the Siskiu N (Enduro), the Siskiu T is a fun-loving trail ripper that’s built for maximum versatility. Think bikes like the Specialized Stumpjumper, Trek Fuel EX, Giant Trance X and Norco Fluid. Unlike those brands however, the Polygon Siskiu T is sold direct-to-consumer in Australia via Bicycles Online. And that means the value for money on paper is impressive. Like, really impressive. Of course a cheap bike with attractive components is one thing, but a bike that puts a smile on your dial when you ride it? That’s another thing altogether.
What’s New For 2021?
Despite looking very similar to the 2020 model, and sharing a similar silhouette to the shorter travel Siskiu D6 we tested last year, the latest Siskiu T actually has a totally new frame for 2021. It’s made from hydroformed 6061 series alloy tubing, and it utilises a linkage-driven single pivot suspension layout. The rear shock has been pushed higher up the downtube on the new frame, so there’s now room for a bottle cage underneath it. The main pivot also sits a little higher, with the aim of improving the Siskiu T’s pedalling efficiency.
Whereas some of the big brands have moved away from wheelsize options, Polygon continues to offer the Siskiu T with both 27.5in wheels (S-M) and 29in wheels (M-XL). Suspension travel is slightly different between the two platforms. You get 140/135mm of travel on the 29in frame, and 150/140mm of travel on the 27.5in version.
Polygon has also taken onboard modern geometry trends with the new Siskiu T. The head angle has slackened out to 65.5°, the reach measurement has grown by 25-30mm across the size range, and the seat angle has also steepened to 76.5°. It’s all very much up to date.
Geometry updates keep the new Siskiu T very much on-trend.
Trail-Tough Build Kit
Polygon offers the Sisiku T in two different spec levels. There’s the Siskiu T7 ($2,699 AUD) and the Siskiu T8 ($3,399 AUD). Both bikes share the same alloy chassis, and to make the most of the progressive trail geometry, a burly parts package.
You get a robust alloy wheelset with 35mm wide rims, bolt-up axles front and rear, and chunky 2.4-2.6in tubeless compatible tyres. 4-piston hydraulic disc brakes come standard with 180mm rotors, and both models get a 1×12 Shimano drivetrain. For those who are after a little extra chain security, it’s possible to add on a full-coverage chainguide via the ISCG 05 tabs.
780mm wide riser bars and a stubby 35mm stem are fitted on all sizes, and thanks to the shorter seat tube on the new frame, 150-170mm dropper posts come as standard. All good box-ticking stuff for a modern trail bike.
While many components are shared between between the two models, the main differences are found in the suspension and running gear. The cheaper Siskiu T7 comes with a RockShox Recon fork, Deluxe shock and a Deore drivetrain. In comparison, the Siskiu T8 features a Fox 34 Rhythm fork, Float DPS shock, and an SLX drivetrain.
Geometry updates keep the new Siskiu T very much on-trend.
How Does It Sit Alongside The Competition?
Though the price of high-end mountain bikes has continued its upward trajectory, there have actually been some terrific improvements in the quality of bikes in the mid and low-end part of the market too. What you can get in a sub-$4K full suspension bike these days is really impressive, and there’s also quite a lot of choice too. To see what the Polygon Siskiu T8 is competing with, here’s a look at some of the other full suspension trail bikes you might consider around that price point;
- Marin Rift Zone 2: $2,999 AUD
- Specialized Stumpjumper Alloy: $3,200 AUD
- Trek Fuel EX 5: $3,299 AUD
- Merida One-Twenty 600: $3,299 AUD
- Polygon Siskiu T8: $3,399 AUD
- Meta TR Origin: $3,499 AUD
- Norco Fluid FS 1: $3,599 AUD
- Canyon Neuron AL 7.0: $3,599 AUD
- Giant Trance X 29 3: $3,799 AUD
Alongside those options, the Siskiu T8 stacks up very favourably, at least on paper anyway. As to how it rides? Read on for a closer look at the specs, followed by our review of the Indonesian brand’s newest full suspension trail bike.
The Siskiu T8 is the more expensive option out of the two. It’s still well under $4K though.
2021 Polygon Siskiu T8
- Frame | ALX 6061 Alloy, Single-Pivot Suspension Design, 135mm Travel
- Fork | Fox 34 Rhythm, GRIP Damper, 44mm Offset, 140mm Travel
- Shock | Fox Float DPS, Performance Series, 210x55mm
- Wheels | Shimano MT410 Hubs & Entity XL2 Alloy Rims, 35mm Inner Width, Tubeless Compatible
- Tyres| Schwalbe Hans Dampf ADDIX SpeedGrip, 2.6in Wide
- Drivetrain | Shimano SLX 1×12 w/MT510 32T Crankset & 10-51T Cassette
- Brakes | Tektro HD-M745 4-Piston w/180mm Rotors
- Bar | Entity Xpert Alloy, 35mm Diameter, 780mm Wide
- Stem | Entity Xpert Alloy, 35mm Length
- Seatpost| Tranz-X Dropper, 30.9mm Diameter, Travel: 150mm (S-M), 170mm (L-XL)
- Saddle | Entity Xtent
- Available Sizes | Small & Medium (27.5in), Medium, Large & Extra-Large (29in)
- Confirmed Weight | 15.08kg (including tubes)
Sizing & Fit
At 175cm tall, I’ve been riding a Medium size in the Siskiu T8, and in the 29in platform. It features a healthy 460mm reach, though the total cockpit length isn’t overly stretched out due to the steep seat angle and tiny 35mm stem.
Bar width is good, but the stock shape is too straight, putting undue pressure on your palms – an issue I also encountered on the Siskiu D6. With a 90mm head tube, the stack is also on the low side relative to the Stumpjumper and Fuel EX. As such, I had to lift the stem up a few spacers to redistribute some of the weight off my hands. I’d love to see Polygon spec a bar with more sweep, and potentially more rise, to elevate rider comfort on what is otherwise a well-proportioned bike.
The bars feel very square. We’d love to see more sweep, and potentially some more rise too.
Setting Up The Siskiu T
Arriving inside a box on your doorstep, the build process of the Siskiu T8 is quite simple, and there’s a multi-tool included in the box to help you fit the front wheel, seatpost and handlebar. That said, the dropper post cable did form a sort of lasso on the front of the bars, so I ended up trimming off some length to tidy things up.
New owners will also need to purchase a shock pump separately in order to get the air pressures setup correctly for their weight, and to get the most out of the bike.
For the rear shock, Polygon recommends 30% sag. Sitting on the saddle while the bike is stationary (get a pal to help you balance while you do this), you’ll want the O-ring on the shock stanchion to move 16.5mm away from the main seal. For my 68kg riding weight, I needed 160psi to hit that sag figure. I set the rebound slightly faster than halfway, with 8/14 clicks.
The Fox suspension is easy to setup, especially the fork with its handy pressure guide.
The Fox 34 Rhythm is even easier to setup, thanks to a handy pressure guide on the back of the fork legs. I followed the guide and went with 72psi in the air spring and set rebound damping with 10/21 clicks. The blue compression lever can be set anywhere between full open and fully locked out. I’d recommend starting with it 1/3rd through its range, to help support the travel under braking and while descending.
Straight out of the box, our test bike came in at 15.08kg with inner tubes and without pedals. While the tyres and rims are both tubeless compatible though, unfortunately you’ll need to BYO your own rim tape, valves and sealant to convert the bike to wheels to a tubeless setup. So that’s another cost to factor in.
Thanks to the wide rims, the Hans Dampf tyres measure up exactly as claimed at 2.6in wide, giving the whole bike an aggressive demeanour. The high volume tyres also allow you to run quite low pressures. Once setup tubeless, and with a Tyreinvader insert in the rear wheel for some added rim protection, I aired up the tyres with 18psi in the front and 21psi in the rear. With the inner tubes gone, the weight of our test bike dropped down to 14.8kg.
It’s not a light bike, but the Siskiu T8 is a comfortable climber.
It Actually Climbs Pretty Well
Despite its big tyres and generous mass for a 135mm travel trail bike, the Siskiu T8 isn’t a terrible climber. It’s certainly no overenthusiastic mountain goat, and I would like to see Polygon spec a smaller 30T chainring instead of the stock 32T, but providing you take a steady approach it’ll make its way uphill just fine.
The suspension is respectfully stable provided that you remain seated, with chain torque helping to extending the shock slightly. The seated position is also excellent thanks to that steep 76.5° seat tube angle, so it never feels like you’re on a recliner when you’re heading uphill. While it is more of a plodder, it’ll get you to your chosen descent comfortably.
The rear shock is quite active in the Open mode though, and on steeper gradients it does have a tendency to sink into its stroke, especially if you stand up to mash the pedals. Combined with the low bottom bracket height, I found myself clipping pedals pretty regularly on technical ascents.
The front end is quite light and wandery on steeper switchbacks, and pedal clearance can be an issue.
To mitigate this, the blue 3-position lever on the shock also offers you Medium and Firm settings. The Firm setting is basically a full lockout, and I’d only recommend using that for riding on bitumen. When off-road, I preferred climbing in the Medium position, which increases the shock’s compression damping to firm up the travel. As well as improving efficiency, this also lifted the BB height to provide a little more ground clearance, resulting in fewer encounters between pedal and rock.
Even still, the Siskiu T8 doesn’t exactly relish in cleaning awkward tech climbs. While traction is good, the short rear end makes it harder to weight the front end, and the light steering sees the front wheel wander on steeper climbs and tight switchbacks. As such, it can be hard to keep it on-line when threading the front wheel around, up and over bigger features. In these situations, it isn’t as composed as the Giant Trance X, and it’s also not as energetic as the Specialized Stumpjumper.
For those who find the steering a little too twitchy, a longer stem would help to slow things down a touch, and it would also improve the climbing position. Bear in mind this would compromise handling elsewhere though, and to be fair, the Siskiu T8 is otherwise a perfectly adequate climber for the type of bike it is.
You get Open, Medium and Firm positions via the blue compression lever.
So Smooth, So Floaty
The flip-side to the active suspension performance is that combined with the high volume rubber, the Siskiu T8 is quite smooth and floaty when bouncing along the trail. This is a vastly plusher bike than the Siskiu D6 I last tested, which comes down to a few factors.
Up front the Fox 34 Rhythm is one smooth operator, with excellent comfort and sensitivity, even compared to the more expensive FIT4 version. It’s balanced well by the rear suspension, which eases into the travel with minimal stiction.
Polygon has built the Siskiu T8 around a 55mm stroke shock, which creates quite a low average leverage ratio of 2.34:1. The overall rate has been flattened slightly for smoother performance, and it’s paired to a Fox Float DPS shock with a high volume air can and a light internal compression tune. The result is that the suspension is nice and active across small and medium-sized impacts at typical trail riding speeds. Both the fork and shock feel supple off-the-top, and the travel is awake and usable all the way through the mid-stroke.
The supple high volume tyres and smooth suspension give the Siskiu T8 great float on rough terrain.
The big volume tyres complement the suspension with plenty of additional damping and excellent traction. Schwalbe Hans Dampfs haven’t been my favourite in the past, but the 2.6in width puts more edges onto the trail, and the tyres are really well supported by those wide rims. That gives them good stability, and very little wobble despite the low pressures I was running. The SnakeSkin casings have also proven to be exceptionally durable throughout testing, with *searches for wooden object* no ride-ruining punctures or sidewall tears. That’s impressive given they’re sub-kilo tyres (892g and 921g confirmed).
Descending at speed over loose rocks can overwhelm the Hans Dampfs, where the big casing and round profile is more likely to float. Narrow ruts need more of your attention too, since the chubbier tyres can occasionally grab an edge when you might not want them to. For folks tackling steeper and looser off-piste singletrack, you may want to consider putting something like a Magic Mary up front for more trustworthy hold through the turns.
Still, the stock tyres are a great match for the Siskiu T8 and typical Aussie trail centre conditions, with a consistent feel and excellent traction on dusty singletrack and through hardpack berms.
Without a shadow of a doubt, the Siskiu T8’s most endearing trait is just how playful it is on the trail. The handling is surprisingly sporty, for what is a relatively plump and capable trail bike.
There are a few key reasons for this. The 430mm chainstay length is really compact for a 29er, and thanks to the short stem, the steering is light and responsive. While this means the Siskiu T8 doesn’t have the same straight-line plough-ability of the bigger Siskiu N, it does mean it’s much more agile.
The sloping top tube results in a tonne of standover clearance, with plenty of room for moving about and leaning the bike over. It’s easy to tip over and initiate a turn, and once you’re tucked in, the active suspension, low bottom bracket, and grippy tyres keep you stuck all the way through.
While I wouldn’t describe the Siskiu T8 as feeling whippy per se, changing direction doesn’t require a load of input. The light steering and short back end allows you to carve turns and pop up the front wheel with ease. Add in the supportive suspension, and the Siskiu T8 handles rollercoaster flow trails like an absolute champ.
Flow trails are a total playground for the capable Siskiu T8.
It’s Got Plenty Of Muscle
As you get up to speed, the Siskiu T8 also holds its line well. Lighter weight trail bikes in this travel bracket can sometimes feel a little skittish, particularly if they’re spec’d with lesser tyres and stiff carbon rims. In comparison, the Siskiu T8 feels steady and unfussy.
The wheels are certainly a contributing factor here. Weighing in at a confirmed 2,494g for the bare wheelset (without tyres, rotors or a cassette), they’re porky. While this does mute acceleration on the climbs, it also helps the whole bike to build usable momentum on the descents. The strong centripetal force adds a degree of high-speed stability, as does the long front centre and slack 65.5° head angle.
Read the full review here.