Polygon Helios C8X Disc review

Ultra-value hydro-electric road

BikeRadar score3.5/5

With its coating of almost logo-free gloss black paint, it may only be keen-eyed observers who'll be gawking at the Polygon frame. Others, however, will undoubtedly be eyeing what’s bolted to it – Shimano Di2 shifting, hydraulic disc brakes and matched carbon wheels. There’s not a single mechanical cable on this ride at a price point where clickity shifting is the norm – which is undeniably awesome.

Polygon is likely a new name to many, but the own brand of this Indonesian manufacturer is quickly creating a stir with its consumer-direct business model in a growing number of regions. Simply put, it means in some regions (such as Australia and the US), Polygon is able to hand you a bike for a price often less than the total cost of the parts bolted to it.

    Ride and handling: an unexpected thirst for speed from an ‘endurance’ bike

    Pitched as an endurance bike, with attached claims of uprightness and comfort, we found the C8X a slightly confused package. While it may have the angles of popular endurance bikes, its reasonably long reach handlebar and 110mm stem stretch things out.

    At this price, hydraulic disc brakes and electronic shifting are a luxury not seen elsewhere: at this price, hydraulic disc brakes and electronic shifting are a luxury not seen elsewhere
    At this price, hydraulic disc brakes and electronic shifting are a luxury not seen elsewhere: at this price, hydraulic disc brakes and electronic shifting are a luxury not seen elsewhere

    A tall head tube means an upright ride, but it's confused by a longish reach

    There’s plenty of head tube length available, which allows for a reasonably upright position, but more recreational riders will be seeking at least a shorter stem to match.

    This is certainly an efficient bike, and there’s no noticeable flex through the bottom or top of the frame. This is great for powering over those short steep climbs and sprinting the Helios up to speed before impressing your riding buddies with your last second high-speed braking abilities into the next corner.

    Despite the relaxed 72-degree head angle, the C8X is no slug through the corners and reacts well to rider input where a line adjustment is required. There are no quirks at high speeds either; it's a balanced experience, with the knowledge that there are superior brakes on standby an added confidence booster.

    25c rubber, a 27.2mm carbon seat post and slender stays should provide for a very smooth ride, but this is no sofa : 25c rubber, a 27.2mm carbon seat post and slender stays should provide for a very smooth ride, but this is no sofa
    25c rubber, a 27.2mm carbon seat post and slender stays should provide for a very smooth ride, but this is no sofa : 25c rubber, a 27.2mm carbon seat post and slender stays should provide for a very smooth ride, but this is no sofa

    Skinny seatstays, 27.2mm carbon seatpost and 25mm rubber

    Unfortunately, throw in a less perfect road surface and things take a turn for the worse. With 25c rubber and a slender carbon seatpost and 'stays, we expected a smooth ride, but it wasn’t always there. The C8X is by no means harsh, but it certainly exhibits more chatter and wheel skip from poorly surfaced roads than the class-leading endurance bikes.

    The high-end Shimano wheels with the mid-width carbon/alloy rim provide a stable platform and a little more air volume, something that redeems the C8X in helping it to stay on the same line as your eye seeks. Making use of these tubeless-ready rims and running things at a lower pressure will help further, but no matter what is done, the frame just isn’t as compliant as its more expensive competition.

    While we were perfectly comfortable on a 53cm sample, the limited choice of just four sizes means not everyone is catered for. This is most certainly a bike for those close to the ‘average’ height.

    Frame: generic appearance conceals a quietly impressive unit

    Usually, when a brand hides its name and covers everything in a coat of black, it’s a sign that either the brand is so well-known that the ‘murdered-out’ style can work… or things simply aren’t worth looking at. Oddly for the C8X, it’s neither of these – sure, the Polygon name doesn’t have the sex appeal of some competitors, but its features are many and the construction quality leaves little complaint.

    Some may say the paint is 'murdered out', otherwise will just say it's boring: some may say the paint is 'murdered out', otherwise will just say it's boring
    Some may say the paint is 'murdered out', otherwise will just say it's boring: some may say the paint is 'murdered out', otherwise will just say it's boring

    A tapered steerer tube hides within

    Using a mid-modulus carbon results in a claimed frame weight of 1.21kg (53cm size) – no feather, but something that should prove suitably durable. All the latest trends are evident in the frame, with a tapered 1.5in head tube, Shimano press-fit bottom bracket and interchangeable internal cable routing, with the hydraulic brakes routed externally for easier servicing (if ever needed).

    The C8X Disc is no old rim-brake frame with disc tabs added either – it’s clearly a ground-up production. Perhaps the best example of this is the closed-dropout axle design used at both ends. Keeping with standard quick release wheels and skewers, the dropouts feature threaded nuts on the driveside that 5mm quick release skewers thread into. To remove the wheel, you must unthread and slide out the skewer.

    Polygon has used a closed axle dropout like a thru-axle would use, but it works with standard 5mm qr skewers and wheels: polygon has used a closed axle dropout like a thru-axle would use, but it works with standard 5mm qr skewers and wheels
    Polygon has used a closed axle dropout like a thru-axle would use, but it works with standard 5mm qr skewers and wheels: polygon has used a closed axle dropout like a thru-axle would use, but it works with standard 5mm qr skewers and wheels

    A closed dropout makes Polygon's system a hybrid between a standard quick release and a thru-axle

    This axle design has been used due to the forces disc brakes can create at the axle and the potential for the brake to pull the wheel out of a traditional dropout if the quick release is not perfectly tight. There’s a little more surface area with the hub and dropouts, but really stiffness isn’t improved over traditional open dropouts.

    The brakes mount via post-mounts, with a 160mm rotor size on the front, and the rear of the frame using an adaptor to space the 140mm mount out to the 160mm rotor used.

    With a 135mm rear axle spacing, we experienced some slight heel rub on the chainstays. it was worst on the left with the brake hose: with a 135mm rear axle spacing, we experienced some slight heel rub on the chainstays. it was worst on the left with the brake hose
    With a 135mm rear axle spacing, we experienced some slight heel rub on the chainstays. it was worst on the left with the brake hose: with a 135mm rear axle spacing, we experienced some slight heel rub on the chainstays. it was worst on the left with the brake hose

    We experienced some heel rub on the wide chainstays

    A problem not yet totally resolved on disc brake road bikes is that crank Q-factor (spacing between the left and right cranks) hasn’t changed while the width of the rear axle has. As we’ve experienced on some other bikes, the Helios Disc is more susceptible to heel rub, and the chainstays are too widely set at the wrong point. It’s most noticeable on the left chainstay where the brake hose sits on the outside, and while not a huge deal for those with a wide stance, it’s something to be wary of for those who ride with their heels in.

    Depending on your ride ambitions, you may be disappointed to hear the C8X has no rack or fender mounts of any kind. Sure it creates a clean looking frame, but there are many aspects of this bike that would otherwise make for a nice adventure-style road bike or high-end commuter if such featured were present.

    Equipment: Shimano’s road disc braking finest with a carbon finish

    For those looking at the C8X, it’s likely that this would be your first road bike with either disc brakes and/or electronic shifting – two things the C8X Disc proudly displays.

    While many are likely to be concerned over the increased complexity of fluid-based brakes and battery operated shifting, these features will actually lengthen your intervals between services. Sure, you must keep your battery charged via the USB port every 1,500km or so, and keep a check on pad wear within the brake calipers – but that’s about it.

    Shimano ultegra di2 out back motors along a wide 11-28t cassette. where it's common for brands to save a little and use a 105 cassette, polygon sticks with an ultegra model: shimano ultegra di2 out back motors along a wide 11-28t cassette. where it's common for brands to save a little and use a 105 cassette, polygon sticks with an ultegra model
    Shimano ultegra di2 out back motors along a wide 11-28t cassette. where it's common for brands to save a little and use a 105 cassette, polygon sticks with an ultegra model: shimano ultegra di2 out back motors along a wide 11-28t cassette. where it's common for brands to save a little and use a 105 cassette, polygon sticks with an ultegra model

    With a Ultegra 50/34T compact crankset, there's a matching 11-28T cassette out back for a wide range

    The beauty of Di2 shifting is that once setup and assuming the derailleur hanger is never bent (and the Polygon's is reassuringly stout), your gears will not go out of adjustment. With the full Ultegra spec, just lube your chain between rides and enjoy what's currently the most reliable and best quality shifting on the market.

    It's a similar story with the braking, which has no cable to contaminate or pads to adjust – there’s little to do other than ride. And with enough riding, you’ll see further benefit with no need to worry about absolute trueness in the wheels or if the rim surface is wearing in poor weather.

    Quality rubber from the germans, these are lightweight, reasonably puncture resistant, compliant and full of traction - just not tubeless compatible : quality rubber from the germans, these are lightweight, reasonably puncture resistant, compliant and full of traction - just not tubeless compatible
    Quality rubber from the germans, these are lightweight, reasonably puncture resistant, compliant and full of traction - just not tubeless compatible : quality rubber from the germans, these are lightweight, reasonably puncture resistant, compliant and full of traction - just not tubeless compatible

    Quality rubber and a Shimano carbon/alloy wheel are exeptional for a bike of this price

    The Shimano RX830 wheelset is the top-end road disc brake hoop from the Japenese giant and is a remarkable choice given the bike’s price and already impressive groupset. The 1.87kg paired weight isn’t anything to boast about, but many other attributes of these are desirable, including the tubeless compatibility in a wide rim design, fast and durable Ultegra-level hubs and the stiff construction.

    Completing the overall build is a handful of Polygon’s house-brand ‘Entity’ carbon componentry. A swept carbon handlebar with semi-internal cable routing is nice, but despite the compact shape in the drops, we would have preferred a shorter reach to the hoods. Holding this in place is an FSA K-Force OS-99 stem, something commonly seen in the WorldTour.

    A wonky bowed shaped saddle unfortunately arrived with our sample. Whether faulty or not, the seat is quite narrow and many riders will benefit from swapping it out.

    With so much carbon on a bike that’s likely shipped to you in a box, it’s nice to see a preset Ritchey Torqkey wrench included with our Australian sample. (In Australia, BicyclesOnline.com.au – the exclusive seller of Polygon over here – gives clear instruction on how to complete the build, and ours arrived with the brakes and gears dialed.)

    In the end, it’s impossible to argue with the C8X’s value for money, and it’s a whole lot of bike on offer. Nevertheless, the heel rub is a concern – and if you’re seeking the absolute comfort on offer from bikes like the Trek Domane, Specialized Roubaix or Cannondale Synapse – no amount of Shimano gadgetry will make this the best bike for you. Also, don’t forget to include the cost of a bike fit in the end price.  

    Click or swipe through our gallery above for an even closer look at the Polygon Helios C8X.

    David Rome

    Former Editor, Australia
    Dave was the editor of BikeRadar Australia until early 2016.
    • Age: 28
    • Height: 173cm / 5'8"
    • Weight: 68kg / 150lb
    • Waist: 79cm / 31in
    • Chest: 89cm / 35in
    • Discipline: Mountain, road and cyclocross
    • Preferred Terrain: Fast and flowing singletrack with the occasional air is the dream. Also happy chasing tarmac bends.
    • Current Bikes: Trek Fuel EX 27.5, SwiftCarbon Detritovore, Salsa Chilli Con Crosso
    • Dream Bike: Custom Independent Fabrications titanium, SRAM Etap and Enve wheels/cockpit
    • Beer of Choice: Gin & tonic
    • Location: Sydney, Australia

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