The 'Pietermaritzburg Polygon'
Pietermaritzburg, South Africa
WORDS Mike Levy
PHOTOS Paris Gore
would be a fitting name for Mick Hannah's 26"-wheeled South African race bike, a machine that Mick and the rest of the team have been working hard to develop all season long, but that Polygon has no plans to turn into a production bike. Sure, some distance between yourself and the bike might trick you into thinking that the blacked out rig is a standard Polygon Collosus downhill bike, but that'd be like saying that a Nissan GT-R isn't quick enough to make you scream like a little girl in fright just because it doesn't look like a Ferrari from 100ft away. You'd be foolish to think that, just like you'd be foolish to think that Mick's secret weapon is a warmed over Collosus.
|There's a few guys up there on smaller bikes, but I feel like I can ride my proper downhill bike and feel as confident as I normally would on it because it is pretty much my regular downhill bike. I mean, it's light enough, fast enough, pedals really well, so I think that it's a really competitive bike here. - Mick Hannah|
It starts with the bike's special race-focused aluminum tubing, which the team readily admits plays a role in this frame not being what they'd want an average rider using for multiple seasons. For one or two big races, though, under the watchful eye of Mick's mechanic, it is just one design point that many teams happily embrace to give their racers an edge. The search for ever lighter weights can sometimes go too far, though, as the team discovered when testing revealed a slight loss in lateral rigidity at the bike's rear end during runs on the Pietermaritzburg track. If it was your average rider, at your average downhill race, that might not mean much simply because there wouldn't be much to do about it. Then again, this isn't your average bike, nor your average race weekend. A machine shop was quickly tracked down, and a block of aluminum was turned into a stiffer lower suspension link for the bike. That explains the link's raw look, then. Problem solved. Geometry is, as you probably expected, also different than what is used on the Collosus. Slacker and lower, no doubt. The finished bike is claimed to be just under 34LB, and Polygon's goal of providing Mick and the team with a new bike that, while giving them advantages over the Collosus in terms of weight and pedalling abilities, doesn't force them to adjust to an entirely unfamiliar machine. Will this strategy pay off? We'll all know in a few days time.
Suspension Design: The production Collosus employs a dual link design, and a closer look at Mick's bike reveals that it does as well, although the positioning of the links, pivots, and shock are completely different than what is found on the production bike. Both of the prototype's links are shorter, with the lower unit not rotating around the bottom bracket like on the Collosus. The bike's shock position has also changed from a laid down angle to standing upright, although it still "floats" between the upper and lower link rather than mounting to the front triangle on one end. Why the change? The team were happy with the bike's suspension performance, and especially its progressive ramp up that helps prevent bottoming, but they were looking to increase its efficiency when it came time to throw down the pedal strokes. The new layout is said to accomplish exactly that, while also contributing to further weight loss. Like many racers, Mick has been using a special FOX air shock during practice, and although he is still undecided as to if he'll race with it, the team were forced to make some modifications to the frame in order to create enough clearance for it throughout the bike's travel. That's why they call them prototypes, though, isn't it?Drivetrain:
Not surprisingly, Mick runs a custom seven speed cassette that allows him to pick and choose the exact gearing that he wants for a given track, with a stack of Shimano cogs making up his range. There is no spoke guard, though, an add-on that most racers who run shortened cassettes can be seen using. His derailleur may appear to be a standard XTR unit, but a second look should have you wondering why you've never seen an XTR derailleur with such a short cage. The Hutchinson United team isn't officially sponsored by Shimano, thereby giving them some freedom to tinker with components that other works-level teams might not have, which is why there is a custom shorter cage on an otherwise stock XTR derailleur. Lighter than Saint, and the right length to boot. Up front, Mick would usually run a 36 or 38 tooth e*thirteen chain ring, but the balls-out speeds of the Pietermaritzburg track see him using a larger 40 tooth option. That's likely a handful of teeth more than a rider of standard human strength would require, by the way, and something that Mick wouldn't know about.
Components: Wheel and tire setups are a hot talking point in the build up to this weekend's race, with many riders running a combination of 650B wheels (Mick's race bike uses standard 26" wheels, don't forget) and less aggressive rubber, at lest on the back of the bike, that will allow their bikes to roll faster and carry more momentum. With nearly zero chance of rain, and not many sections that require the braking forces found on tracks like Val di Sole or Fort William, the Pietermaritzburg course is ideal for such things, and Mick's Polygon is no different. His rear tire is a yet to be named prototype from Hutchinson that, while certainly bearing a resemblance to the Squale mounted up front, has been designed to shave time through faster rolling. To this end, its knobs are not only lower than usual, but also more tightly spaced, therefore creating a larger contact patch and less of a tractor tire feel. The tire's casing is special as well, with rigid downhill walls on the sides and a more compliant section over its crown, a combination that gives it support and flat protection while shaving a fair bit of weight compared to a standard downhill tire. Up front, Hannah has decided to go with a surprisingly small
volume 2.3'' Squale, Hutchinson's newest production downhill tire, with it mounted on Mavic's Crossmax Enduro front wheel, used to save on some rotating weight. A more standard Deemax is used for the rear wheel. Spank and Crank Brothers make up the bike's cockpit, and a set of Formula brakes slow it down. One standout bit is the custom carbon fiber XTR shifter mount, a small item that probably only shaves a few grams but is likely to be sought after by a good portion of readers who appreciate such things.www.polygonbikes.comwww.hutchinson-ur-team.comPhotos by Paris Gore