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It’s a buzzword. “Mass centralization” is one of those terms engineers have used in many vehicle applications that marketing types have grasped onto and shoved out to the media and the general public. But what’s the meaning behind it, and how does it apply to sleds?
It seems pretty straightforward. You take the majority of a vehicle’s mass and center it in the vehicle as much as possible, both laterally and fore and aft. Seems like a good idea, and in theory, this would lead to consistent handling and better performance. Only it doesn’t – not in cars, and not in sleds.
As
AmSnow Tech Editor Olav Aaen pointed out in his article, “
Mass Centralization: Is it really an advantage, or simply marketing hype?” (
American Snowmobiler,
Dec. 2011), Rolls-Royce engineers were keen on handling issues caused by a truly centralized mass when navigating the bumpy dirt roads in the early 20th century. Early car engines were placed well behind the front axles. This meant there was not enough mass or inertia to compress the front springs, Aaen explains. The solution was to move more engine mass over the front axle. With more mass over the front end, the spring could better soak up uneven terrain.
The same progression can be seen in the evolution of snowmobiles from the 1960s and ’70s, when engines were practically in the lap of a rider who sat much further back on a sled, to the rider-forward chassis designs of today. Moving the engine and rider mass over the skis resulted in better handling machines.
Olav could see the furture when he wrote, “Every manufacturer is making its sleds lighter, and the correct mass distribution will be a critical part of new sled designs …” Ski-Doo’s new Gen4 REV platform revived the buzz about mass centralization. The problem is this is not a case of true mass centralization. The engine still sits forward over the skis, but Ski-Doo has centered the engine mass laterally. In other words, the engine is now centered between the skis, but still well forward of what would be considered centered between the front and rear bumper. As Olav said, it’s not so much about centralizing as it is about proper mass distribution.
In theory, the lateral centralization of the engine mass should make the sled more responsive to rider input, and our mountain crew has noticed an increased responsiveness in the 2017 Summit line. Trail riders will feel an improvement when they lean into that first tight hairpin.