Polygon Siskiu D8

Despite being in the bike industry for nearly 25 years, Polygon has managed to fly under the radar of most riders until just a few years ago. Based originally out of Malaysia, and with a large manufacturing plant in Indonesia, Polygon started branching out from their roots in city bikes around 10 years ago with a significant push into the mountain bike arena. More recently, they gained significant exposure with the UR Team, which includes Aussie stars especially Mick and Tracey Hannah, and just this year they sponsored Sam Reynolds and Kurt Sorge at the Red Bull Rampage.

With the relative saturation of existing brands in the MTB market, Polygon initially struggled to get a significant dealer network in Australia. So instead of following the traditional distributor/retailer model, they decided to cut out the ‘middle man’ and sell their bikes direct to the public. There is now a limited dealer network where you can try a Polygon, but with their primarily direct-sell method, they hold a big price advantage over other brands.

Our Siskiu D8 test bike is a perfect example; RockShox suspension front and back, Shimano SLX/XT drivetrain with a clutch derailleur and Mavic wheels, and it’s all yours for under two grand, delivered to your door. Yep, that’s right; a genuine off-road dual suspension bike with 120mm travel, 650B wheels, quality big-name parts and a solid looking frame for $1,999. Too good to be true? Well read on my friends…

Polygon Geometry
The Siskiu is designed as an XC trail bike; the type of bike that works perfectly for the majority of riders, the majority of the time. Keep it away from serious downhill trails and don’t let your World Cup XC aspirations get too carried away; beyond that the Siskiu will have your back. The 68-degree head angle is slack enough to feel stable at speed whilst still keeping the Siskiu manoeuvrable at lower speeds and in tight trails. The bottom bracket sits around 330mm off the ground with the stock tyres; that’s pretty low. This helps you to feel ‘in’ the bike, especially when combined with the 27.5-inch wheels.

From there things get a little less focussed. The 438mm chainstays, whilst not super long, add more of a sense of stability than playfulness to the rear end. Up front the 605mm top tube and 707mm front centre on our large sized test bike make the Siskiu very short by modern standards. To be honest, the numbers feel like a well-sorted ‘medium’ sized trail bike from a few years back. At 182cm I found it a little cramped at times, but I certainly enjoyed the quick handling in the twisty bits on some of our local trails. The problem here is that there’s currently no XL option. Until that changes, I think that riders over 180cm are just going to have to give the Siskiu a miss; a pity really, because it offers a lot of performance for not very much money.
In terms of frame design Polygon haven’t gone out on a limb with the Siskiu, and that’s not a bad thing at all. Whilst there’s plenty of hydroforming evident in the cross section of the front triangle, the tubes themselves are more or less straight. The completely straight seat tube is a bonus as it means you can slam the saddle all the way down if needed. Because the seat tube lines up directly with the bottom bracket, there are no weird changes to the effective top tube length as you adjust saddle height; the actual seat angle is the same as the effective angle.

The rear triangle has mud room for miles and uses unexciting but rock solid rectangular section tubes to drive its linkage-actuated single pivot suspension design. The only obvious concession to price is the quick release dropouts, but at this price you’re not going to find anything else. Our frame and shock weighed in at a respectable 3,061g, and even though it’s not the absolute stiffest frame we’ve seen, it’s on par with plenty of significantly more expensive bikes. The all-in weight of 13.55kg without the supplied pedals (which I wouldn’t recommend for genuine off-road use) is also very competitive with bikes costing $1,000 more. All-in, tThe frame package is solid and light enough that it shouldn’t hold you back one bit.

I do have a couple of minor gripes with some of the frame details however. Firstly, whilst the internal cable routing keeps things looking neat, the tiny entry and exit ports will make any future cable changes a lot like going fishing, and equally frustrating. Secondly, the only water bottle mount is under the down tube where’s it’s effectively unusable—this will be an annoyance for some.

Thirdly, and much less obviously, the pivot and suspension mounting bolts are poorly sized and quite soft; they’re quite likely to round out if you have to use any amount of force. It’s the only area where it seems readily apparent that Polygon has cut production costs. If you need to replace the hardware over time, it isn’t likely to break the bank but I anticipate a few stripped bolts and some blue language from Siskiu owners in the future. Other than these few quibbles, Polygon has done a commendable job of building a light and solid frame from which to hang some fairly glitzy (for the price) kit.

Fancy Bits
One of the most compelling reasons to look at the Siskiu is the outstanding parts spec for the price; I can’t think of another brand that’ll give you a similar bike with the same kit for less than $3K. In fairness, I didn’t get along with the overly straight handlebar or 80mm stem, and swapped them for something more familiar, but that’s a personal preference thing. I’d also suggest that anyone looking at the Siskiu put some money aside for a dropper post; it deserves one to really utilise use its full potential.

While the Shimano 615 brakes don’t look flash, they work as well as most of their more expensive siblings—if you ever needed more power it would be easy to upgrade to a 180mm front rotor. Mounting the SLX shifters via Shimano’s I-spec system keeps the handlebar tidy (aside from the fork remote, which we’ll get to), and if you wanted to 1X down the track, the old-school band clamp front derailleur can be completely removed for a cleaner look.

The clutched equipped XT rear derailleur keeps drivetrain noise down and dramatically helps chain retention (I never dropped it), and it’s good to see the direct mount rear hanger being used. This gives a more precise and direct shift action by removing the b-knuckle from the derailleur. Lastly on the Shimano front, the SLX cranks are an absolute value for money favourite, and the threaded bottom bracket should ensure many years of creak-free service. The drivetrain and brakes are all spot on, with absolutely nothing to change.

The Mavic Crossride wheels held up very well and they certainly add some serious badge value to the Siskiu. That said, the inner width of 21mm is very narrow by modern standards, so be prepared for plenty of tyre roll in corners if you want to run tyre pressures below 30psi. This lack of sidewall support is all the more evident because the frame, and to a lesser extent the fork, are is all pretty solid. Hopefully Mavic will one day wake up to the benefits of wider rims, but alas it isn’t today.

The 18-point freehub engagement means there’s some lag when you first start to pedal. It’s not an issue for general trail riding, but it can be a downer in technical climbing where you’re trying to ratchet a few pedal strokes in between rocks. Once again we can’t be too fussy given the sticker price. I’ll also say that the Smart Sam tyres are a good match for the Siskiu; fast rolling and hard wearing with a reasonable amount of predictable cornering bite; just keep them off wet rocks and roots where they become treacherous.

The last element of the parts puzzle is the RockShox suspension front and rear. Both the Monarch RT and the Recon Gold are proven performers that punch above their weight, and they are absolutely trail-worthy. There is a caveat here though, with both the fork and the shock.

The fork performs admirably when in the open setting; just set it with around 20% sag, dial in your rebound speed and go hammer some trails. Its damping isn’t class leading, but it’s more than capable of keeping your wheel on the ground and pointing in the right direction. The lockout allows you to firm things up for smooth fire roads but the remote lever is bulky and relatively flimsy—I suspect it’d only take one or two offs before it’d be smashed to pieces.

You may be thinking, ‘oh well, I’ll just take off the remote as I don’t use fork lockouts anyway’. Unfortunately this isn’t as simple as you’d think, as the default setting on this particular fork is locked out. Remove or damage the remote and you’ll have no front suspension travel. You could swap the damper cartridge for one that’s designed to run without the remote, but that will cost upwards of $150; certainly a bitter pill to swallow.

On more than one occasion I also knocked the remote midway through a descent, and that’s not the way to inspire downhill confidence. For anyone using the Siskiu as a ‘proper’ mountain bike – and I think it deserves to be treated as such – we’d recommend the following modification. Simply insert a short piece of inner wire where the remote cable should go, wind the damper to the fully open setting and then lock it in place with the grub screw. Yes it’s a bodge, but it’s a very neat and cheap one that will be all but invisible once it’s done.

And now onto the Monarch shock. I’d normally run about 25% sag on a trail bike, but the suspension on the Siskiu is so progressive that this setup left the last third of the travel unattainable, even on high speed chunder and moderate drops. In the end I settled on 35% sag as the baseline. This allowed me to use all of the travel without slamming the bump stop, although it did mean much more pedal bob, especially in the big chainring. Fortunately, the lockout lever makes short work of smooth trails where efficiency is king, and because it has a blow-off threshold, you won’t wreck the shock if you forget to switch it back on for a rough downhill.

I tried to remove the air can to see if there were any volume spacers that could be removed to make the suspension more linear, but the dodgy mounting hardware wanted to strip as soon as I took the allen key to it. So I decided to leave it be, and in truth it was just fine.

Siskiu for You
As you’re probably not buying it from a bricks and mortar shop, the Siskiu will come to your door in a box. This shouldn’t be an issue for anyone who is competent in doing their own basic mechanical work and they do offer an online video tutorial, but at the end of the day it’s up to you to check the bike thoroughly before hitting the trail. According to Bicycles Online, every bike is checked by them before it’s sent out. Despite this, our test bike had a some loose disc rotor bolts, one of which was slightly cross threaded. We also had to tighten up one of the pivot bolts and the remote lockout lever was fitted to the wrong side of the handlebar; all easy enough to fix but it serves as a reminder that you’ll be responsible for the final safety check of your Siskiu. Oh, and don’t forget, you’ll have to know how to set up the sag and rebound on the suspension too. If you’re not comfortable with all of this, get the bike assembled by an independent bike mechanic and budget for the additional expense.
Once that’s all sorted and you whip through the first few berms, clean the first uphill pinch and nail that rock garden, are you going to wish you’d spent extra on a big brand bike? Not likely! As I’ve intimated already, the Siskiu is a very capable and neutral handling bike that’s spec’d better than anything else near its price range.

There’s very little pedal kickback through the rear suspension and there’s also very little stiffening under brakes—for a simple design the Siskiu’s rear end is well executed. I’d say it climbs and descends equally well, which is pretty much the brief for a modern XC trail bike. The only time it got unsettled was on steep rock ledge filled climbs. Running lots of sag means it sinks down deep into the travel, provoking plenty of pedal strikes. It also causes a rearward weight shift that leaves the front wheel wandering. Lock the shock out in these situations and you’ll lose traction as the wheel struggles to follow the terrain. While it isn’t the most playful bike I’ve ridden, it also not the least. I’d say it’s equal parts business and pleasure; a balance that many newer, or often not so new, mountain bikers are looking for.

Polygon are on to a winner with the Siskiu. Spec wise it’d be a pretty good proposition at close to $1,000 more, but for the $1,999 asking price it’s pretty much unbeatable. The short sizing means that if you’re much over 177cm you’ll be best off looking elsewhere, but if you’re less tall and looking for a proper mountain bike on a budget, this is one you definitely need to check out. I suspect we’ll be seeing a lot more bikes from Polygon in the years to come.

Thumbs Up
Amazing spec for the dollars
Stiff and respectably light
Effective suspension design

Thumbs Down
Poor quality suspension hardware
Hard to utilise all of the rear travel
Final build QC is largely up to you 

Specifications
Frame:  Siskiu ALX Alloy
Shock:  RockShox Monarch RT 120mm Travel
Fork:  RockShox Recon Gold w/remote lockout 120mm Travel
Headset:  Polygon Internal Sealed Caged Bearing
Handlebars:  Entity Expert Alloy 740mm
Stem:  Entity Expert Alloy 80mm
Shifters:  Shimano SLX i-Spec
Front Derailleur:  Shimano Deore
Rear Derailleur:  Shimano XT
Cassette:  Shimano Deore, 11/36 10-speed
Chain:  Shimano HG50
Cranks:  Shimano Deore 22/36
Bottom Bracket:  Shimano Threaded External Bearing
Pedal:  VP-349 Alloy
Brakes:  Shimano Deore M615
Wheels:  Mavic Crossride
Tyres:  Schwalbe Smart Sam 2.1
Saddle:  Entity Flux
Seatpost:  Entity Expert, Alloy 30.9mm
Weight:  13.55kg without pedals (19.5 frame 3,061g)
Available Sizes:  15.5, 17.5 and 19.5-inch (tested)
Price:  $1,999
Distributor:  Bicycles Online (02) 8599 2209 / www.bicyclesonline.com.au