POLYGON SISKIU D6

£899 (w/ £5 GO Outdoors card) Lightweight for a budget full-sus, the D6 is a great platform for upgrades

The 120mm Siskiu is more of an XC machine than an all-rounder trail bike, in terms of travel, geometry and design intentions. On paper, with its budget yet reliable parts and suspension spec, and a shape that’s in touch with modern XC race geometry, it ought to deliver the goods, but does it?

THE FRAME

Polygon’s ‘Faux Bar System’ suspension layout – a linkage-driven single-pivot design with horizontal shock – gives the small size a pleasing look, with the downward sweep of the top tube echoed by the line of the seatstays. A one-piece rocker link actuates the SR Suntour Raidon LO shock to deliver 120mm of travel.

Geometry is conservative, as is generally to be expected on an XC bike. The small size feels compact with its 650b (aka 27.5in) wheels and short 425mm reach and 572.2mm effective top tube length. At 75.5 degrees, the effective seat tube angle is quite slack, while the 67-degree head tube is more upright than on the other bikes here, speeding up low-speed handling, at the sacrifice of some stability once the pace picks up.

THE KIT

This D6 model is one up from the bottom of the range and sports an SR Suntour XCM 32 coil fork, which is slightly more basic than the XCR 34 on the GT and has skinnier stanchions (upper tubes). Shimano provide their MT201 hydraulic disc brakes and 10-speed Deore drivetrain. Unbranded rims on Shimano hubs are shod with Deli (nope, us neither) Spiderbait 2.25in tyres. Entity provide most of the finishing kit, the exception being an unbranded, 150mm-travel dropper seatpost, which is a welcome addition at this price point. It’s good to see a robust rubber chainstay protector, too. At 15.2kg, the complete bike isn’t ‘XC light’, but is the lightest on test.

THE RIDE

Polygon have delivered a fun-to-ride XC bike. Climbing on, the geometry feels well-proportioned and the saddle well-shaped. On moderate-tosteep ascents, the Siskiu feels heavy and slow to respond, but on flatter, mellower terrain, the fast-rolling Spiderbait tyres help you to maintain a good pace. The 10-42t cassette has a narrower range and harder bottom gear than the 11-48t block on the GT, so we were sometimes left

wanting for more gears, especially on technical climbs. Riders who are still working on their leg power may find grinding at a low speed tiring.

Considering the price tag, though, these details are easily overlooked, especially given the fun we had on laps of the new bike-park-style trails at Glentress. The flat handlebar gives the cockpit a somewhat awkward feel, but fitting a replacement with a few degrees of backsweep would be a cheap and easy upgrade, and would give a more comfortable position for your wrists and upper body. Thankfully, Polygon have fitted a 45mm stem, which keeps steering sharp – in a good way – and makes the Siskiu responsive to changes of direction.

The dropper post – which lets you drop the saddle down with the flick of a bar-mounted lever – is a huge bonus when it comes to maintaining flow on undulating trails or getting the seat out of the way on the downhills. Our small bike came with a 150mm-travel post, which was overly generous for our tester’s 28in inside leg measurement. However, at this price, it was an inconvenience we were willing to adjust to.

We also found that the Siskiu had a very bouncy ride, and any time the bike went light over trail features, a harsh knock could be felt as the shock topped out. With no external rebound or compression adjustment, there wasn’t much we could do about this. Thankfully, Polygon say it was likely a one-off issue.

More positively, the XCM fork soaks up and smooths out trail chatter well, and takes steps and small drops in its stride – provided you can ignore that top-out clunk. Riders looking to stick to smooth trails with only the odd technical feature are unlikely to find this a problem.

Well-priced bike with competitive XCstyle geometry but a few spec niggles