TESTED: Polygon Siskiu T9 mountain bike

BikesOnline have continued to deliver mountain bikes to riders around Australia who are looking for a great value way to get onto the dirt. The Polygon Siskiu range has always been popular, and the more recent updates to the frame designs and models available have only served to increase their popularity – there are even two e-bike models now, with the T6E and T7E, the former of which we have tested in late 2023. While Mike has also tested the $2299 Siskiu T6, BikesOnline also released the new $4299 Polygon Siskiu T9 in early 2024.

The Siskiu T9 shares the same frame as the rest of the range, including the size specifc wheel sizing. This trail bike is available with 27.5” wheels in small and medium frame sizes, with 150/140mm of travel front and rear respectively. For sizes from medium to extra large, the bikes are built with 29” wheels and the travel is a 140/135mm setup. So if you're medium-ish size, you can choose what wheel size you're after. I’m testing a medium 29er on test from BikesOnline.

Photographer: Gerard Lagana
Tester: Anna Beck
Riding Experience: Little bit of this and that, XCO, XCM, Gravity and DH that one time…
Generally Rides: Santa Cruz Blur, Yeti SB140, Cervelo Aspero
Height: 168cm
Weight: 64kg
Bike Test Track: Brisbane trails

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Initial Impressions

The Polygon Siskiu T9 was delivered to my house via the editor who was kind enough to build it and drop it off, but as a direct to consumer business, you can head to the BikesOnline website and your bike will be shipped to your door: no editor required. You need to choose your size (recommended size charts are available online), any accessories, pay your money and your bike will be delivered. As mentioned in the T6 review, BikesOnline have a 30 day free returns policy if you unbox the bike and realise it's not for you. More details on that are on their website.

Having ridden a range of bikes from Polygon, it’s easy to see that they have evolved from the Polygon of bygone eras. The T6 was a bargain, but the Siskiu T9 on test here can be bought for a song: for $4299 you get a 140mm Fox 36 Performance Elite fork with Grip 2 damper, a 135mm Fox Float X rear shock, XT drivetrain, TransX seat post and TRP EVO DH 4-piston brakes. If you priced this all out individually, you can see the value there: you can piece out the components and pretty much reach the RRP, that’s not even including the frame and wheels. Wheels on this bike, while not lightweight or high end by any means, feature Shimano MT400 hubs and 35mm Entity rims, they are solidly built and I found them to be reliable.

The frame itself features internal cable routing and room for a bottle cage, while the finish of the tubing isn’t anything out of this world, the forest green and sandstone colour way look understated and smart. Their suspension design is linkage-driven single pivot, a simple design that ‘reduces the weight of the frame and increases stiffness’ with a claimed 10% reduction in anti-squat.

The Siskiu also promises modern geometry that can rival many more upmarket brands. Polygon cite ‘high-speed control’ and ‘responsive handling’ as key features of the Siskiu due to its short 425mm chain stays and a 65-degree head tube angle. The mixture of flickability and stability isn’t all: the steeper 77 degree seat tube angle should iron out potential any pedalling concerns, especially important for taller riders on larger frames. While the medium sports a 460mm reach, the short stem and forward position feels very centred. It’s evident that the alchemy between the numbers allows the Siskiu T9 to avoid the old slack like a sled feel of many trail bikes, instead placing you right in the middle of the frame. But for the million dollar (actually only $4299) question: how does it ride?

On The Trail

Initial impressions were drawn from the first ride at my local trail network, featuring a few runs of the black/dark blue trail in order to dial in a few things like tyre pressure, position and suspension settings. Each run requires a 10+min fire road climb with or without some singletrack climbing, so it’s a great loop to understand how the bike performs climbing on fire road and singletrack; and how it descends on rocky technical trails and fast flow.

Firstly, the climb up highlighted the T9’s centred geometry: you’re really in the centre of the bike, unlike some other trail bikes that position you to feel like you’re pushing from behind the bottom bracket. This is likely due to steeper seat tube angle (77deg) combined with a shorter stem complimenting the longer reach. At 168cm, I am at the lower end of the recommended size chart for the medium T9, however the fit felt just right and I would struggle on a smaller frame. For those who are on the upper end of the size chart, I would compare your existing bike's geometry and rider style before pulling the trigger on size.

This centred climbing position together with the ample rubber and traction of the Assegai means the T9 tractors up tech climbs, if without eagerness due to the overall heft. The two-position climb switch on the Fox Float X Performance shock featured a pedalling platform allowing for efficient power transfer and snappier climbing to the top of the run making a noticeable difference from climbing in the open setting. With the XT 12 speed drivetrain featuring a 32T chainring and 10-51T cassette range, I didn’t yearn for extra gears on all but the steepest of climbs.

The wheel and tyre combination adds lots of traction, but in tech sections with a slow entry that require momentum to clear, and entering into jump or speed sections of trail with short entries you do feel the heft. However, the Assegai excelled in delivering a predictable and stable ride in loose over hard conditions, and on more mild gradient climbs I found that once up to speed I was able to tick along pretty well.

But talking about how well the T9 climbs misses out on the important spice: how does it descend? Pointing downhill, the bike really delivered. For my current rider weight of 64kg I set up the Float X at 25% sag, with 134psi and rebound at four clicks. The fork sat at 79.5psi with quite light rebound and compression settings.

The Polygon Siskiu T9 comes alive the more input you put into it while avoiding feeling sketchy or unstable; it has successfully married the maneuverability of a short travel trail bike with the capability of something more reminiscent of an enduro bike. This ability is bolstered by the the Fox 36 up front, it’s stiffness was noticeable compared with a Fox 34. Due to being a bigger fork than could have been specced on the bike, the 36 rewards a centred and front-heavy rider position, especially for a smaller rider, which was supported with the cockpit spec of short stem, wide bars and slack 65 degree head tube angle. It also meant that the ride itself felt stable and supported with exceptional small bump sensitivity (thanks to the Grip 2 damper), but smaller riders may find the weight of the 36 a lot to handle; it’s a lot of fork! The low rise Entity bar was good, but I'd prefer to swap to something with more sweep if this was my own bike.

The front end of the T9 was planted and stable, and thanks to the Fox Float X the rear of the bike remained steady and capable, at least 95% of the time. For fast, rocky, technical trails hit at speed I did hit the limit of the rear end’s 135mm travel as I toed the line of keeping the rear planted vs out of control a few times. That is one drawback of the short 425mm chain stays that conversely facilitate the bike’s playful, responsive feel on less hectic trails. I still had room to move with the Float X’s rebound settings, but that’s likely to temper the problem rather than resolve it completely. In a way it’s complimentary of the T9: it’s a medium-travel trail bike that’s begging you to ride it like a much bigger bike…but on occasion has to remind you it’s only 135mm travel.

The thorn in the side of the T9 is the TRP DH EVO brakes, they lacked both the sharpness of Shimano and modulation of SRAM’s brake offerings, and came out of the box feeling quite underwhelming and mushy. While they bedded in well, they were definitely the one component that underperformed on the T9. That being said, the whole package is still a bargain and while they weren’t fantastic, they did the job, and if you found yourself underbraked it would be easy to justify an upgrade given the price point of the bike.

Our Take

The Polygon Siskiu has always represented value in all its iterations and the T9 is no exception. At the low-end of the price range for a trail bike in 2024 money, you’re getting the drivetrain and suspension that wouldn’t be out of place on a carbon boutique trail bike worth well into five figures. While the frame and wheels definitely result in some extra beef that can be felt when the trail points up and during accelerations, it’s a small penalty for the price point: especially considering the frame exceeded my expectations on rides quality .

For the emerging trail rider after a robust build for weekend shreds, those looking to upgrade their Covid hardtail purchase or your teenager that’s riding more and needs a reliable drivetrain and suspension, you can’t go past the T9. If you’re after a pure enduro sled, thats there in the Polygon Collosus. For the average rider this bike is more than capable enough to take you between the bunting for the occasional race run, weekend shuttles with mates or longer endurance trail rides.

The editor once said I had a long list of dislikes, to which I respond that I mainly like stuff that works, feels good and is reliable (bonus points if it’s light). While the Siskiu T9 isn’t getting any bonus points, I would put it pretty strongly in the ‘like’ list. It’s a trail bike with a solid build that rewards rider input: if you enjoy an active ride and popping off roots, rocks and jumps and working the trail, this could be the bike for you.

Full specs of the Polygon Siskiu T9

RRP $4299
From BikesOnline
Weight 15.64kg (as tested)
Available Sizes S, M (tested), L, XL
Frame Material Aluminium
Fork Fox Float 36 Performance Elite, GRIP2, 140mm
Shock Fox Float X Performance, 135mm
Shifter Shimano Deore XT 12sp
Derailleur Shimano Deore XT 12sp
Crank Shimano Deore XT 12sp, 32t, 170mm
Chain KMC X-12
Cassette Shimano Deore 10-51t, 12sp
Hubs Shimano MT400, Boost
Spokes Black, stainless
Rims Entity, 35mm inner
Tyres Maxxis Assegai TR EXO, 29 x 2.6”
Brakes TRP EVO DH 4-piston 180/180mm
Stem Entity Expert 35mm
Handlebars Entity Expert, 780mm
Seatpost TranzX, 150mm
Saddle WTB Volt