The not-so-minor details
Polygon Collosus DHX
Great geometry - check your size though
Unbeatable build kit
Pedal feedback at lower speeds
If you haven’t heard of Polygon before, we wouldn’t be surprised. When it comes to most things from Indonesia, Australia is generally pretty disengaged (aside from our favourite political football, asylum seeker boat arrivals). But this is a brand worth paying attention to – they’re actually one of the world’s biggest manufacturers, producing bikes for a number of other brands- and this bike in particular warrants extra attention.
Why? Well not just because it is simply absurd value for money, but also because this is the very same bike that Mick Hannah won the National Champs on this year.
It’s a long way from the glory of the World Champs to the downhill tracks of Sydney, but they’ll have to do! We dusted off the full face, strapped some knee pads onto ageing legs and took this silver beast into the bush.
Holy Toledo, what a beast! In glistening silver and white, with CNC machined alloy aplenty, the Collosus DHX is an impressive looking bike. Your eye is naturally drawn to the web of alloy and pivots, housing the FOX RC4 shock, nestled around the bottom bracket. It’s a complex looking arrangement, but in reality there are no more pivots than any other twin-link rear suspension design.
The lower pivot incorporates the bottom bracket shell, which is encircled by two massive bearings. This link pivots directly around the bottom bracket axle and also drives the rear shock. This main pivot uses pinch bolts, with threaded inserts so you can’t stuff the frame – this is a blessing as disassembling this linkage would require some serious spanner time and pinch bolts mean less stuffing about.
All the weight is down low and very central, great for stability. The shock is surprisingly easy to adjust despite its location and it’s well protected from debris flung off the rear wheel by a neat carbon shield.
If we look at the suspension behaviour, the linkage gives a wheel path that’s just like a high-pivot design. The rear wheel moves backwards quite markedly at the start of the travel, before tending more vertical in the deeper parts of the travel. It’s an incredibly supple design too, and the three-inch stroke FOX DHX RC4 moves at the slightest touch.
Geometry wise, the DHX isn’t as raked out as some, with a 64-degree head angle, but you can fit an AngleSet if you’re inclined to slacker it further. For our local downhill tracks, anything slacker is overkill, and we’re inclined to say that’s the case for most Australian terrain.
We never changed the wheelbase, leaving the chain stays at 440mm, but you can move alter the length by 5mm in either direction. This simply involves fitting different dropout and rear brake mount inserts, but we were happy with the geometry anyhow so we didn’t mess about.
In this setting, the wheelbase was 1173mm, which is a tad shorter than some of the competition in an equivalent size (we were on a medium). For example, a Giant Glory has a wheelbase of 1211mm, a Norco Aurum 1192mm. Going up a size to a large adds another 50mm to the wheelbase. As we said above, for most Australian riding, we feel that the shorter wheelbase is pretty appropriate, but going to a size large frame may still be the preference for riders out there seeking maximum stability.
We’re not sold on the Marzocchi-made Maxle style rear axle. We’d prefer a standard bolt up arrangement which would provide more clearance and is also more reliable.
The cable routing, underneath the down tube, is clean but not hassle free. Because of the way the suspension moves, it’s necessary to have a fair bit of cable hanging below the bottom bracket. With such a low bottom bracket height, we did occasionally end up with some sticks hitching a ride, caught up in the gear and rear brake lines.
We’re not aware of another downhill bike available in Australia that can come close in this area; the component spec found on the DHX doesn’t make financial sense. The very best from FOX, Shimano, Mavic and Schwalbe adorn the Collosus, for a price that’s around $700 less than the other king of value, Giant’s Glory 0.
Saint brakes, shifting and cranks need no introduction. The 36-tooth chain ring is encased in an MRP Mini G2 chain guide with bash guard (well needed, given the low bottom bracket height) also a quality item. The suspension is from the top shelf too, with a Kashima-coated FOX 40RC2 fork and DHX RC4 rear shock, both delivering eight inches of travel.
The yellow hoops of Mavic’s Dee-Max wheelset have been always been at the top of wish list and it’s extremely rare to see them on an off-the-shelf bike. Ordinarily they’re an upgrade, but here they are, and shod in Schwalbe tubeless rubber too. The Muddy Mary tyres are awesome, and the Trail Star compound (rather than the gummier Vert Star) is a good choice from both durability and rolling speed perspectives. They’re set up without tubes too, so pinch flats are a thing of the past.
Kore provided the bar, stem and funky T-Rail saddle and post. Kore isn’t a name you see so often any more, but it looks great, with the white bars setting off the bike perfectly. The build kit really is perfect, are reasonably light too, keeping the whole bike to 17.26kg.
It’d been a little while since we’d swung a leg over a downhill bike (too much time on the trail bike!) and it’s always a good feeling to get back into it. The Polygon made it easy for us, giving us no nasty surprises as we re-learnt the lines.
Suspension set up can take a while when you’ve got so much adjustability on hand. Fortunately we found the spring rates (medium in the fork, 350lbs for the rear shock) perfect. A few clicks of high-speed compression damping was all we needed to feel totally confident in the FOX 40′s performance.
The rear end is more complicated. Polygon’s FS2 linkage gives the DHX a very pronounced rearward axle path for the first half of the travel. This is great when it comes to compliance, but the associated chain growth can be clearly felt through your pedals. We wound on a few turns of low-speed compression to keep the rear end more stable under pedalling and minimise this feeling. This trait that really was only pronounced at slower speeds – once up to speed, pedalling over rough sections of track was less of a chore.
Polygon importer, Bicycles Online, had informed us that some riders were opting to stiffen the rear shock by 50lbs, but we didn’t feel the need. While we did find the bottom of the travel on a few occasions, adding some high speed compression damping gave us the feeling of support we wanted.
The overall stiffness of the bike is praise worthy too, with the rear end matching the immense lateral stiffness of the FOX 40s. It’s a reassuring feeling, giving you the confidence to keep your feet up and slide the bike into corners or cut inside berms, or get you out of trouble if you come into land a bit crooked.
Drivetrain noise wasn’t a problem we expected, but the Polygon makes a bit of a racket on the trail. There’s no chain slap protection on the seat stay (get some Frame Wrap on there), and the Saint derailleur sits super close to the chain stay when in the higher gears, leading it to knock against the frame loudly. It’s something we’ve encountered before on our Norco Aurum long term test bike, and it can be easily remedied by fitting a small adaptor that creates more clearance. (Watch this video for more info).
Going fast is where the Polygon is best; when you’re not pedalling, and it’s got a lot of rocks to run over. The super supple suspension and stout fork make light work of heavy terrain, and the FS2 suspension carries momentum exceptionally well.
This isn’t just a great value bike that you’d buy for the build kit alone, oh no, this is a great bike full stop. We’re not saying that $5000 will buy you Mick Hannah’s skills and enormous calves, but it will get you a bike that has proven itself as the fastest in Oz. And it’s a bike that’s got us itching to ride more downhill too – we’re stoked.