Polygon Siskiu T8 review

A fun to ride budget ripper that could shine with a few upgrades

Our rating 
3.0 out of 5 star rating 3.0
GBP £2,500.00 RRP | USD $2,500.00

Our review

Polygon's Siskiu T8 is a fun example of a lower-cost trail bike that's ready to rip
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Polygon’s Siskiu T8 is a solid reminder of how fun even low- to mid-range bikes have become. It used to be that bikes under a certain price point suffered from a lack of decent frames and parts, but those days are behind us.


The $2,500 Siskiu T8 sports 140mm of RockShox travel, Shimano gearing and discs, and a ready-to-shred geometry.

Two wheel sizes are available: 27.5-inch wheels on the Small and Medium frame sizes, and 29-inch rubber on another Medium as well as the Large and X-Large.

Things are good when even budget builds come with a 45mm long stem
Russell Eich / Immediate Media

Polygon Siskiu T8 specs

  • ALX aluminum frame
  • Faux bar rear suspension, 140mm travel
  • 140mm RockShox Revelation RC fork, Deluxe RT3 rear shock
  • Shimano XT/SLX groupset, 1×11-speed
  • Entity XL2 wheels with Schwalbe Nobby Nic tyres with Addix Speedgrip compound
  • 14.3kg / 31.5lbs, actual weight, size X-Large
The dropper remote let it down with a wobbly lever. It would hit the brake clamp if positioned too closely
Russell Eich / Immediate Media

Dialed geometry

Polygon blessed the Siskiu T8 with geometry that’s on point with most of today’s standards. The reach, head angle, wheelbase and bottom bracket height are a close match to most carbon wonder bikes. And it works well.

Interestingly, the seat angle was a bit slack, but it made riding wheelies incredibly easy. Having short 435mm chainstays and a solid pedaling platform let the bike settle into the balance point easier than most. 

Again, for a $2,500 bike it’s absolutely refreshing to have geometry that nearly duplicates the riding position of many high-end machines. 

Muted suspension feel

With 140mm of travel on both ends, the Siskiu T8 falls squarely in the trail bike category.

It didn’t feel like it, though. The rear, in particular, felt shorter in travel. I experimented with the sag, starting at 20 percent and making my way to a touch over 30 percent. 

Even when fully open, the Deluxe RT3 rear shock always felt like the compression was way too high
Russell Eich / Immediate Media

I played with the rebound, backing it off until two clicks from wide open and I lubed the Deluxe RT3’s seals. According to the shock’s O-ring fun meter I was getting full travel, but the bike just felt like it had less travel than it did. 

Inside, the shock wasn’t filled with volume spacers though, only two were installed. 

Quite good uphill

That taut rear end suspension made for good climbing. The Siskiu T8 gained altitude very well. There was really no need to flip the Deluxe RT3’s climb switch, the pedaling platform was firm enough with the shock wide open.

It’s worth mentioning that the seat angle is relatively slack, so riders with short legs might find the pedaling position a bit old school.

Capable on the downs

Pointed downhill, that firm pedaling platform also made the bike fun to actively ride. By that I mean that the Siskiu T8 worked better when pumping transitions, sprinting out of corners and unweighting over the rough stuff.

In each of these circumstances, instead of having to push through all of the suspension’s travel before leveraging against the bottoming ramp up, it responded quicker because I was able to push off of the pedaling platform much sooner in the shock’s stroke.

This middle link kept the frame’s stiffness feeling right
Russell Eich / Immediate Media

But, when tired or riding lazy that same suspension action pinged off rocks and provided a wild, bucking ride. If your riding style is less assertive, a shock re-tune could be in order. 

On the front end, it was nice to see a RockShox Revelation fork mounted to a bike at this price point. Most of the appeal falls on the 35mm stanchion chassis, which was stiff and confidence inspiring, especially with the big 29-inch hoops.

Its Motion Control damping isn’t nearly as refined as other more expensive forks, but the stroke actually matched the feel of the Polygon Faux bar rear-end quite well. 

The 51mm fork offset lead to neutral handling
Russell Eich / Immediate Media

Steep sections of trail were handled with way more expertise than a bike at this price should. Kudos goes to the sorted geometry with slack 66.5-degree head angle, stout fork and big 29er wheels.

Interesting specs

Oddly shaped, the handlebar was a rather unfortunate thing. It was annoyingly flat and had a weird lack of sweep. The grips were equally odd with a single lock-on collar but no inner sleeve. That meant only the inside of the grip was held in place while the rest of the grip was free to spin around. 

I did not get along with these bars. Too flat, not enough sweep
Russell Eich / Immediate Media

Tranz-X supplied the 150mm dropper post. The party post itself worked perfectly and with less side-to-side play at the saddle than other droppers etched with big name brands.

The under-bar remote lever showed cost cutting though. Its clamp came loose a few times and, if positioned too close to the Shimano brake lever, it would hit and interfere, not allowing dropper post actuation. Even properly snugged, the lever always had some play. 

Shimano’s no-name MT500 disc brakes felt budget as well. The levers had Shimano’s iconic shape, but the overall braking power was laughable. On a positive, the lack of power could be incorrectly praised as good modulation because it was hard to lock up either wheel. 

I had my share of issues with the Entity XL2 wheels. Loose spokes, numerous flat tires, torn rim strip, non-tubeless set up, etc.
Russell Eich / Immediate Media

I struggled with the Polygon house-brand Entity XL2 wheels. They were one of the first wheelsets I’ve had in ages that weren’t taped for tubeless out of the box. Because of that, and the rear suspension’s muted action, I experienced more flat tires on the Siskiu T8 than any other bike in recent memory. 

They weren’t strong either. I managed to knock the rear wheel out of true more than a few times, with a number of spokes losing tension even after repeated truing with a tension meter. 

With a hard, fast-rolling Speedgrip compound, the Schwalbe Nobby Nic tires were likely aiming to make the bike feel quicker
Russell Eich / Immediate Media

Which leads to the Schwalbe Nobby Nic tires.

On soft dirt, the hard knobs dug in, but on dry, rocky, loose conditions they were overwhelmed. The hard Speedgrip compound rolled quick but lacked a tacky, sure-cornering bite. A softer compound tire on the front would be my first parts swap, or maybe second, after the bar and grips.

Lastly, the single-ring crank was branded Prowheel. It’s an off-brand, but in reality, it performed flawlessly and felt decently stiff. 

Polygon Siskiu T8 bottom line

Despite an interesting spec and some wheel issues, the Siskiu T8 was a fun, capable trail bike.

For the $2,500 price, it’s entirely ready to be pushed hard and thrown into challenging terrain. Depending on how big you are, or rowdy you ride, the wheels might have a short life. 

Polygon calls the rear end what it is, a Faux bar
Russell Eich / Immediate Media

Standout features are its tough alloy frame, proper geometry and name brand suspension units, which are some of the most important pieces to get right on a mountain bike. 

It’s impressive to see wide rims, a dropper post, and the Shimano name on the drivetrain and brakes too. It’s the sort of bike that’s ideal for new riders who’ve fallen in love with mountain biking and are looking for their next bike. 


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Product Specifications


Name Siskiu T8 29er
Brand Polygon

Bottom Bracket Threaded
Rear Tyre Schwalbe Nobby Nic Speedgrip
Chainring Size (No of Teeth) 32
Wheelset Entity XL2, Boost
Stem Entity Expert, 45mm
Shifters Shimano SLX
Seatpost Trans-X dropper post, 150mm
Saddle Entity Assault
Rear Tyre Size 29x2.35
Rear Derailleur Shimano XT
Brakes Shimano MT500 discs
Handlebar Entity Expert, alloy, 780mm
Front Tyre Size 29x2.35
Front Tyre Schwalbe Nobby Nic Speedgrip
Frame Material ALX aluminum
Fork RockShox Revelation RC Solo Air, 140mm
Cranks Prowheel
Chain KMC X-11
Cassette 11-speed, 11-46
Brake Levers Shimano MT500