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Ski Tech Evolution

Advances in snowmobile ski technology deliver new designs, improved feel and more options for consumers
RELATED TOPICS: AFTERMARKET | MODS | MAINTENANCE
2017 Yamaha Sidewinder Tuner III skis
Each manufacturer has ski technology developed in conjunction with its machines. But there are plenty of aftermarket ski options too!
“Skis are the most patented piece of hardware on a snowmobile.”

That is what Yamaha’s Product Manager told to the editors of AmSnow many years ago. So it is certainly no surprise that there are so many small variations out in the marketplace. There are literally too many to mention in this article and every one of them could be the best thing for a certain customer. But here’s some of my own personal observations.

Decades ago, USI (Ultimate Sports Inc.) owner Kevin Metheny started seriously changing aftermarket snowmobile ski design, but up until his work, and subsequently several others, your choices were limited to steel skis or aftermarket aluminum skis for racing. Metheny is the inventor and developer of the first practical and commercially successful plastic skis.
Yamaha 1990s Kevin Metheny plastic skis development
Kevin Metheny’s early successful plastic skis led to rapid OEM development after the 1990s.
Yamaha Tuner ski Deltabox chassis sleds
The Tuner ski from Yamaha was first used on Deltabox chassis sleds.
Transition to plastic skis
Metheny’s idea caught on quickly, as the plastic ski was slippery on the snow (i.e., faster), lighter, better looking and rust free. Nowadays, plastic skis are the only kind of ski available on newer sleds and come in all kinds of interesting colors, special shapes, and targeted keels/sizes/carbides and more for conditions varying from Midwest groomed trails to off-trail deep-snow Mountain riding.  

Plastic skis also were invented just as the industry was transitioning from leaf-spring front suspensions to longer travel and more precisely controlled IFS suspensions. Rear suspensions were also getting longer and more controlled travel, and all this combined into a new and quickly evolving game of handling and control that is still going on today.

The increased speeds of the better handling sleds put new demands on ski design. Ski width, ski length, keel depth, keel shape, rocker, center of pressure in relationship to the mounting bolt, and more all play an important part in steering balance and what the rider feels at the handlebars. Too much keel behind the spindle bolt can result in too much self-correcting action, making the skis hard to steer. A keel that’s too centered makes the ski too easy to turn and in need of constant corrections.

Yamaha’s first electric power steering on their Deltabox chassis Apex machines back in 2011 was a good example of this. The power steering actually turned out to work TOO well, and the new machine slightly over corrected in tight turns, which sometimes made them a handful on windy grooved trails. The following year, Yamaha corrected the problem by moving the spindle bolt 5/8 inch further forward, which moved the center of the keel the same distance behind the spindle bolt, giving the ski more self-correcting action and complementing the stronger power steering. This rather small correction transformed the sled into a smooth and predictable performer, with the added benefit of lighter power steering action.

Realizing that there were still gains to be made in ski design, Yamaha then set out on a larger development program that ultimately resulted in the newest version of the "Tuner" series of skis, the Tuner III. The dual-keel, dual-runner design has a large assortment of carbide runners in varying shapes and carbide insert lengths. By choosing different carbide runners for the inside and outside keels, a rider can fine-tune the handling of the skis to suit his or her riding environment.
double carbide runner options snowmobile skis
There are several double carbide runner options available today.
Ski-Doo DS2 DS3 skis off-trail deep snow
The DS2 and DS3 skis from Ski-Doo are off-trail oriented and made for deeper snow.
In the 1990s, all manufacturers quickly jumped on the new plastic ski design trend, but this is 20 years later and things have ramped up on the OEM side. Differences are obvious, like Arctic Cat’s newest trail ski, the ProCross 6, which is six inches wide with a single deep keel, whereas Arctic’s mountain ski, the ProClimb-7, is seven inches wide at the front and then tapers to 6.5 inches in the center. The ProClimb-7 also has a wider saddle and a longer bolt with spacers that can be moved from the inside to the outside to change the width of the ski stance. Ski-Doo’s new DS2 (deep snow 2) and now DS3 is another example of a new design from an OEM that is tunable with their flotation extensions that can be added for more off-trail deep snow performance. Each manufacturer has taken to the ski stance adjustability for mountain sleds. Arctic Cat and Yamaha even offer ski stance adjustability in many of their trail sleds too.

Trail skis & carbides get better!

Although ski width and keel depth is important, especially in off-trail, deep-snow conditions, most snowmobiling takes place on well-groomed trail systems. When running on harder surfaces like hard pack or ice, the selection of a suitable carbide runner is just as important as the shape/style of the ski itself.  

With the emergence of more precise movement of the skis due to constant development of better and longer travel (and deeper keels and different ski designs) problems known as “hunting” or “darting” of the front end became more common. This would occur when a single carbide fell into a groove on a hard-pack trail already worn down by other sleds. If the other ski’s carbide also fell into a similar groove, it might force the first out, and a side-to-side “darting” motion would follow. This is irritating, so a number of aftermarket companies continue to do their best to solve the problem.

One working solution turned out to be twin carbide runners – two shorter carbide runners mounted on a common plate with space in between. This meant that one carbide would not fall into a groove, because the other would hold it up. The length of the twin carbide runners needed was also usually less than that of the single long carbide, so if both were to fall in, they would not resist turning so aggressively. It was also less likely that the twin carbides on the other ski would simultaneously find two grooves to fall into, so the side-to-side darting problem was almost completely eliminated. Several traction companies including Woody’s Traction and Stud Boy make dual carbide runners.
Ski-Doo Pilot TS adjustable ski carbide snowmobile
Pilot TS adjustable ski carbide Ski-Doo snowmobile
The Pilot TS adjustable ski carbide is the latest OEM ski/carbide system development. The amount of carbide exposed can be adjusted.
There was also a much larger benefit of installing twin runners. Riders often pointed out that they seemed to grab the ice better, especially with long carbides, but they were also much easier to steer due to their shorter length. Not only did you get good grip in the corners, but it also came with much less steering effort. No darting, good grip and less steering effort add up to a winning combination, and although these runners obviously are more expensive, installing a set is often a no-brainer when you experience the benefits on the trail. As a result of these new developments, a number of new skis are now coming straight from the factory with twin keels or twin (double/dual) runners.

New ski inventions keep coming, and Ski-Doo’s latest trail focused effort is the Pilot TS adjustable carbide ski. On this unit, a knob at the front of the ski makes it possible to lower the carbide down through the keel in order to provide more grip in varying conditions. See any of our comparison or long-term articles to get our full opinions on these skis, but the adjustability benefits are there, along with drawbacks like more weight.

Back to the beginning … kind of
So do you need different skis for different conditions, or is it possible to develop a ski that performs well both on the groomed trail and in deep snow? After inventing the plastic ski, Metheny did not rest on his laurels. Instead, he kept up a steady development program, teaming up with Stud Boy Traction to develop the best twin carbides. Then he recruited the assistance of famous Indy Car racer and avid snowmobiler Bobby Unser, who is credited with developing the first IFS racing ski suspension when he worked as Team Manager for the Chaparral Racing Team in the winter.

Metheny traveled out to Unser’s favorite riding areas in Chamas, N.M., and the two tested a steady stream of new ideas. The result was the USI “Triple Threat” ski. Only 41 inches long with a standard shallow keel, the ski is 7 inches wide but tapers down to only 3 inches in the rear. This makes it easier to turn in deep snow. The Triple Threat ski also has a clever provision for a separate “rudder” to be installed in a slot at the back.  Different size rudder plates come with the skis for fine-tuning the steering balance in deep snow.
Ultimate Sports Inc. USI snowmobile ski front view
Front view of a USI ski from the main keel to the step-up, then the outer rib stage.
USI Triple Threat skis trail cross country
USI’s Triple Threats have extra rudders and are liked by many trail and cross country riders and racers.
The words “Triple Threat” refer to the staged cross-section of the ski itself. The stage is the standard part of the keel, then it transfers into the first load-bearing surface, which is only a total of 5 inches wide and ideal for groomed trails. Outside of the 5-inch platform is a shallow rib, and then the ski has a small step up to the top load-bearing surface, which is a total of 7 inches wide (1 inch wider on each side) with a shallow outer rib. The stepped-up 7-inch-wide surface works well in deep snow, but it does not present any additional drag on a groomed trail. The stages are ideal for a variety of conditions.

I’ve personally tested the Triple Threat X2 skis a lot on my trusty Polaris Edge 600 “mule” and found they work well when mounted with Stud Boy double runners and the smallest rudder installed. The grip on hard-pack trails was good; the sled steered around corners like it was on rails, with little handlebar effort. Flotation was also good in deeper snow, but the steering effort was still light due to the shorter ski and its sharply tapered rear. The X2 is often preferred by many Enduro racers due to a little less snow on those cross country tracks and fewer jumps and due to the variability of low snow and chewed up trails or racetracks they ride on.

In the Triple Threat, Metheny and Unser have developed a ski that does most all things at least fairly well to pretty darn good. Does it eliminate the need for more than one set of skis altogether? Probably not because many folks go from one extreme to another, but it comes close.

C&A Pro Skis was one of the first ski manufacturers to actively use snocross racing as a development arena. Snocross offers a different challenge than groomed trails or deep mountain snow. Since the snow on snocross tracks is often man-made, it gets a much looser and grainier consistency than regular nature-made snow, especially after taking a hard pounding from practice, racing and re-grooming. C&A’s snocross skis float and steer well in these conditions because they are longer (45 inches), wider (7.25 inches) and have a deep, 1.5-inch keel. The larger floating area on the C&A allows for easier landing when they come off big jumps and riders steer with keel due to so much loose snow on the snocross tracks.

For comparison, C&A’s RZ trail performance ski is 44 inches long, 6 inches wide and has a keel that’s only 0.75 inches deep. This also means that the trail ski is 1.5 lbs. lighter than the racing ski. In between the racing and trail skis, there is C&A’s mountain ski (45 inches long, 8 inches wide, 1-inch-deep keel). While the snocross ski places an emphasis on steering with the deep keel, the design of the 8-inch-wide mountain ski is focused on flotation. C&A’s range of skis illustrates the different design philosophies required to meet all the varying riding conditions snowmobilers encounter on a daily basis, or over the course of a full season.

Mainstream manufacturers and aftermarket pioneers are constantly developing and tweaking front suspension and skis. Riders can expect to be surprised by a steady stream of new ideas, both in ski design and runner development, to complement the new advances in chassis and suspension design.
Starting Line Products Mohawk crossover skis snowmobile
SLP Mohawk Ski
Yamaha Tuner III skis dual keel snowmobile
The two keels on Yamaha’s Tuner III skis are meant to help reduce darting.
C&A Pro Skis XCS crossover snowmobile
C&A XCS Skis
Curve Industries XSM skis optional hardware snowmobile
Curve Industries XSM Skis & Optional Hardware
NEW SKI TECHNOLOGY
SLP: Newest Mohawk Ski Strikes Balance

Starting Line Products has been a premier aftermarket supplier to the snowmobile industry for decades, and it now has three distinct ski options. These include the SLT trail ski, the Powder Pro off-trail ski, and the new Mohawk crossover ski. With a wide 7 3/8-inch top with traction grips, this ski offers good flotation, and SLP claims the hourglass-shaped rocker keel with gull wing edges totally reduces darting. What you’ll notice first about this ski is its flexibility. That is important for any off-trail or obstacle riding. Conforming, yet keeping the keel rocker and rigidity is important here. This ski is built specifically for rider-forward crossover machines. Check out any of SLP’s thousands of aftermarket options, including their new Mohawk ski at: www.slp.cc.

Tuner III Skis: What’s the Best Setup?
So far, we’ve found that six inches of carbide on the inside and four inches on the outside work best for most semi-aggressive riders in many different condition applications with this ski. We will be studding our long-term demo Yamaha Sidewinder unit, so we will see if this setup works well with studs and let you know what our thoughts are after a full season. Stay “Tuned!”

New C&A XCS Skis: Best of Both Worlds
Last season, we tested the new crossover XCS skis from C&A Pro Skis, and we found them to be very good for both on- and off-trail riding. They are tapered to allow for sidehilling moves, but they also have outboard keels and “snow scoops” to maintain a consistent and predictable grip on the trail. We would feel confident recommending these skis for a variety of riders and applications. They are not cheap at $459 a pair, but AmSnow Test Riders will tell you that a good pair of skis that fit you and your riding style can make a huge difference. More info: www.caproskis.net

Curve XSM Skis & Optional Hardware
AmSnow editors have used Curve XS skis for years, but the new XSM backcountry-focused ski from Curve is a newer development in the shapely line of skis from Curve. It is primarily for off-trail riding with a stepped “mountain profile” on the outside of the shaped skis to aid in sidehilling. These skis also offer enhanced floatation over trail skis and many older mountain skis. You can also change the skis from one side to another to quickly shift the focus from off-trail to on-trail performance. Curve Industries will tell you they are the handling experts, and they offer many other options to fine-tune your skis. The Thruster add-on is an on-trail/off-trail application for Curve skis that offers more flotation and aggressive cornering in piled-up snow, fresh, and other conditions. They come in 8 or 17-inch options. In addition, Curve offers its Leading Edge products (2- or 4-inch options) which decrease darting, improve tracking, and decrease possible carbide degradation from objects you might hit on the trail. XSM skis – $279.99, Thrusters – $79.99, Leading Edge – $69.99 or $89.99. More info: www.curveindustries.com
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