5 Features that Make the Perfect Sled

December 2019 Feature Steve Janes

Polaris—Pro-RMK 850

When it comes to designing a snowmobile made for the most extreme riding conditions, Polaris has hit a homerun with the Pro-RMK 850. Its only limitation is the person straddling it. Good, aggressive riders make this snowmobile look unstoppable.

Polaris has designed the Pro-RMK 850 to stay level and lift on top of the snow to take advantage of its lightweight design. Its narrow design reduces unnecessary drag so it can take full advantage of its power to press forward. 

Although the Pro-RMK 155 was a lot of fun to ride, I would likely take the 163 with the Series 7 3-inch track.

Here are the five features that top my list on this particular model.

1) AXYS Rider Balanced. The AXYS platform is the foundation of how the Pro-RMK performs. Its rigid design relies entirely on the rider to initiate precise and predictable turns; the better your balance, the better the performance. This is one snowmobile that works in harmony with a rider’s ability.

Because it stays level in the snow, the entire track is working to lift the sled and rider on top of the snow to reduce drag. It responds to foot positioning on the running boards and leverage through the handlebars. You lean and pull, ever so slightly, and the sled responds. This is why Polaris excels in extreme terrain conditions.

2) Light Weight Dominates. Polaris makes the lightest snowmobiles on the mountain. Although you wouldn’t think that 15-20 lbs. make a difference, when you’re wrestling with a chunk of metal in five feet of fluff, you feel every ounce.

Polaris has worked hard to reduce weight. Everything added to the Pro-RMK has a specific and functional purpose. There is no extra plastic, no extra aluminum. Polaris engineers have looked at every individual part on their snowmobile and removed any excess material. It’s this commitment to ounces that has allowed Polaris to eliminate pounds.

3) AXYS Chassis Clearance. Although we’ve already mentioned the platform’s rigidity and lightweight design, we also want to acknowledge how it pairs with the front and rear suspension to increase its clearance in the snow and to continue to reduce unnecessary drag.

The aluminum over-structure is lightweight and durable for all types of riding. Taller spindles increase clearance to reduce drag. The rear suspension allows for improved weight transfer while allowing the track approach angle to climb on top of the snow. The rail design keeps the track in contact with the snow for improved forward thrust.

4) QuickDrive Low Inertia Drive System. The QuickDrive System, or belt drive, transfers the power from the clutches instantly by eliminating power-robbing chain and gears. This leads to quicker revving and instantaneous lift because it reduces rotational inertia by 21 percent.

All this translates to flickability. You touch the throttle and the entire snowmobile responds. This really shines in the trees when you’re picking your lines with extreme limits on response time. You don’t have the luxury of anticipating your next turn. You see a gap in the trees and you either make it or you’re stuck. This is where Polaris shines.

5) Body Panel Design. Rather than designing a hood focused on mirror imaging (where the left side is basically identical to the right side for visual balance), Polaris has used the minimum amount of plastic and shaped it to cover the contour of the components under the skin. Thus, the snowmobile is as narrow as possible from top to bottom, side to side.

By maintaining a compact body panel geometry, the Pro-RMK is capable of holding the steepest sidehill lines. This allows the edge of the ski and track to maintain contact with the snow when the competition’s side panels cause their sleds to wash out on their sides. The PowderTrac XT running boards on the 850 are also designed narrow to not interfere with the Pro-RMK’s sidehilling capabilities.

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