Each new season of Snow Goer magazine kicks off with a Q&A with top engineers and designers, taking readers much deeper into the new technology than they will see anywhere else. The story below was published in the October 2024 issue of Snow Goer. (If you were a subscriber, you would have seen this a year ago!). As we conduct this year’s interviews on 2026 technology, here’s a look at the 2025 Tech story on the then-new Ski-Doo RAS RX front suspension geometry and Pilot RX ski. The new geometry has been expanded more broadly for 2026 in Ski-Doo’s lineup as well as into the Lynx lineup. (See the Tech 2025 Arctic Cat 858 engine story here.)

Geometry Secrets On Ski-Doo’s RAS RX/Pilot RX Combination

Ski-Doo gave a sharp new handling edge to select 2025 snowmobiles with new RAS RX front suspension geometry, plus a new Pilot RX ski.

Combined, these upgrades make the so-equipped MXZ models plus the new 43-inch Backcountry X-RS model stick to their intended line much better in corners in all conditions.

It’s a notable enhancement that’s easily felt when riding, but only the most observant of sledheads will notice the changes when looking at the snowmobiles. Super observant Ski-Doo veterans may be able to eyeball spindles that are 26mm taller (1.02 inches), upper A-arms that were raised by the same amount and lower A-arms that were raised 11mm.

Far less noticeable to the naked eye are lower shock mounts moved slightly outbound, revised sway bar linkage, a new lower steering arm mount and increased trail in the ski mount. But every millimeter counts when messing with suspension geometry.

New skis with a stepped keel, meanwhile, go further to help provide far less push in corners with loose snow.

When introduced, Ski-Doo officials spoke about moving the roll center closer to the center of gravity, stabilizing steering and more. But how did it all come together, and were there any trade-offs? To find out, we interviewed Maxime Dormoy, the Ski-Doo project engineer who was instrumental in RAS RX and Pilot RX development.

SNOW GOER: When did work begin on what would become the RAS RX platform (the suspension geometry and ski)?

MAXIME DORMOY: “The suspension project started in the winter of 2022. That winter, we were doing a lot of field tests with the development of the MXZ 850 Turbo R, and our team could feel the mass of the turbo that is a bit higher on the sled. We saw an opportunity to improve the sled’s handling. Most of us were pointing toward our front suspension for improvements.

“So, as a proof-of-concept, we built prototype sleds with the [MXZ X 600 RS front] racing suspension. We began by trying the racing geometry but we tuned the shocks and the springs with let’s say a more ‘civilized’ calibration. The racing geometry is obviously outside of the scope of normal people like me! So, we tuned the shocks and the springs and tested these prototype sleds.

“Out of this test session, the benefit of the new geometry was clear. We were all surprised with how much flatter the sleds were in corners. So, it had very good handling on the trail, but it was not perfect with the capacity of the suspension. That’s because the racing suspension has less suspension travel than our trail sleds. Our RAS X suspension was the leading suspension for bump capacity without any doubt, and we were not ready to lose this benefit.

“So back at the office, [Product Development Project Manager] Frederic Desjardin gave me a challenge: He said, ‘OK Max, now you have to give me a geometry with the racing feel but while keeping our capacity, our travel.’”

SG: The RAS X platform introduced for model year 2021 had many of the same sort of goals. Did the move to the REV Gen5 in part cause the need to go back into the geometry to re-address these things?

DORMOY: “I would say yes and no. As you know, the snowmobile industry is developing new technologies at an incredible pace, and we improve the product each year. That’s very exciting, but we also learn more about our product, about our team, about our customers. So I don’t know if it’s exactly because of the G5 platform that we felt the need for an improvement, but we were ready. We had better software, we had a bigger team, we’d done a lot of tests and we knew there was an opportunity to improve – maybe more specifically with the G5.”

 SG: Which came first, the suspension geometry changes or the ski?

DORMOY: “The suspension came first because, as I said, with the 850 Turbo R, the engine raised the bar as far as performance, so we knew we needed a better front suspension. But we were still limited by our Pilot X ski because it would push in corners in loose snow. Even if we had a new front suspension, we could still not push the sled like we wished to do. The suspension and the ski came around the same time and were developed together.”

 SG: When introducing the RAS RX package, Ski-Doo officials said you wanted to get the roll center closer to the center of gravity (CG). Most snowmobilers know the concept of CG, but maybe aren’t as familiar with roll center. Define these in simple terms, and the advantages of getting them closer together to each other.

DORMOY: “Roll center was one of the main parameters of the project to improve handling in corners. The roll center is studied when we have lateral load, like when going through a corner. You can study the roll center in the corner when both of your skis are on the ground – otherwise it does not make sense.

“The roll center axis summarizes the load on the A-arms. This is a mathematical simplification to isolate the frame from the A-arms. With the roll center, you can identify where the frame will pivot in space at a given time. So, every time your suspension moves left or right, the roll center is moving with it. Let’s say at a steady state in a corner with a lateral G force of 0.3, we can calculate where the virtual pivoting point of the chassis will be. With the force acting on the center of gravity and the distance of the pivoting point (moment arm), we can calculate what we call the roll moment. The force multiplied by the distance gives us the roll moment. To fight against the roll moment, we have the springs and the sway bar. We can tune each of these parameters to reduce the rolling motion of the chassis.

“This is what we did with the RAS RX: We tuned every parameter, we tuned the roll center, we tuned the spring position and we also tuned the sway bar linkage to reduce as much as possible the rolling feel of the chassis.”

SG: Many knowledgable snowmobilers know they can control some of their chassis roll with spring adjustments, but you’re also now doing it with geometry. Is there a way to quantify the impact of each alteration you made – for instance, the A-arm positions vs. the shock position, etc.?

DORMOY: “Yes, there is. At the top of the list is the roll center, the second one is the sway bar and the third one is the spring position – the shocks are a little more tilted [and therefore the springs also]. We’ve reduced the roll of the frame on RAS RX by 20 percent, but it’s not a completely different thing. It is still a Ski-Doo suspension – we have the Ski-Doo behavior, we kept our capacity, but it is a refinement on the roll movement.”

SG: Let’s get into the front geometry. We understand that it all works in concert, but many changes were made. Let’s start with the A-arms and spindles: You went with a 26 mm taller spindle and created a wider split between higher-mounted A-arms. What’s the primary benefit?

DORMOY: “The A-arm positions are defined by our roll center. They are a result of changing the roll center position, and this is the choice we made to keep good suspension dynamics – the motion and everything. The ski leg [spindle] is taller, but the first goal was to raise the roll center, that’s the reason for having higher A-arms. Because we kept the same chassis, the mounting points on the chassis are the same, so the way to raise the roll center is to change [outer] A-arm positions as well as the height of the ski leg.”

SG: Why did you bring the outer mounting points of the shocks outward?

DORMOY: “As I said earlier, the springs fight the roll moment, so by changing the lower mount position and tilting the shock, we increased the distance of our spring and its leverage against the roll center. So, again, if you calculate the force,we have a bigger reaction from the springs.”

SG: Explain why the upper A-arms have a bit of a bend to them. Did that allow more travel as well?

DORMOY: “It changed the motion ratio a little bit. There is more travel mainly because of the shock configuration. The bend of our A-arms is primarily due to chassis clearance.”

SG: What was the purpose of adding a few millimeters of ‘trail,” meaning the position at which the ski bolts to the bottom of the spindle?

DORMOY: “Again, our focus was on cornering, and in a corner the ground is not always smooth, and the nature of the snowpack is not constant – it is often changing with soft snow, hard snow or ice, and sometimes there are bumps or old sled tracks. It is often a mess in corners! After a few tests, we discovered that having more trail helps to stabilize the steering and the skis. There is a lot of force acting on the ski in corners, and suddenly it encounters ice or soft snow or hits a bump. to make that.

“By having more trail, there is less feedback in the handlebar. So you can better feel what is happening and decide ‘can I go faster, do I need to brake or turn even more,’ for example. It increases the feeling that you have, and the steering is more composed. With steering, you can feel small changes at the handlebar. Even a millimeter or two, you will feel it, or a tiny, tiny friction somewhere in the joint, you will feel it. We are very sensitive to that. The numbers are very small but they make a difference for sure.”

SG:  If adding more trail was the only change you made, wouldn’t that slow down the steering in turns?

DORMOY: “Yes, I think you are right when saying that, but here we’re talking about aggressive riding. For sure, for this purpose, it is better to increase the trail a bit to stabilize the steering. But you know, not everybody is riding at full speed and being aggressive in corners, so if you increase the trail too much to get stability, the effort will be higher at the handlebar. We have to find a good compromise for each of our sleds.

“On the MXZ X-RS we are aggressive because this is a racing-style sled. With the RAS RX, we changed the trailing and we also changed the steering motion ratio to compensate for that effort. The lever at the back of the spindle where the tie rod attaches is lengthened a little bit so the handlebar can exert more leverage on the spindle.”

SG: How do you end up at exactly 26 mm higher for the upper A-arm and 11 mm higher for the lower A-arm? What happens if you go higher or lower with either, and how do you find the exact position for final production?

DORMOY: “That’s a good question. We do software simulations to predict the dynamics of the vehicle, so we have a lot of graphics that we can extract. We can tune one parameter at a time and we can see the results. This is very interesting – we can loop many times to get to our objective. But, you know, to design a suspension, there is no ‘book’ that tells you how to do it. For me, I see it like a recipe. It’s like cooking a cake: add more salt, less water, whatever. We set our objective with everyone on our team, and as engineers we have to find a recipe to make that.

“But you know, I’m not only talking about the technical things. We also have a lot of constraints from the manufacturing world. We have to find a bit of compromise for our assembly lines, for our suppliers, for transportation, for the weight, for the cost, for each one of them. But we have a lot of experience. I did not build that suspension by myself: We are a team and we do the tests together and have a lot of brainstorms. Yes, we came up with that geometry, but it was not our first geometry. We did many geometries and then worked on three.”

SG: We know available design software keeps getting better, but how much of that final tune relies on actually building parts and getting test riders out on the snow in various conditions?

DORMOY: “At Ski-Doo, we are very lucky because we do a lot of tests on the snow. At the end, it’s always test sessions that will decide where to go. On that side, I looked at the objective, did my simulations and calculations and we built three different vehicles with different geometry. Then we went on the snow to test these geometries, and we tuned the shock calibrations and the springs [for each]. Then, when we are ready, we had session tests with many people and this is where we decided if it was good or not and where we had to improve. I think the success for Ski-Doo is really our team. Our bosses, they are not only management, they also challenge us on things that you cannot imagine [laughs]. They know everything about the sled so that’s an advantage for sure. In the end, it’s not simulations that decided if it was a go or not, it was on the snow.”

SG: Let’s jump to the Pilot RX ski. What was the stated mission, and how did you get to the final design with the stepped keel?

DORMOY: “We needed more traction in loose snow. We chose to address this with a two-step keel design because, on hardpack snow, it is better to have a smaller keel for handling. This is the goal of the two-step design: On hardpack you still have a small keel so it’s easy to handle and the grip is more than enough. But as soon as you jump into soft snow we have the bigger keel that comes into play. The lateral force that can push the ski is much bigger than on the Pilot X.

“We also wanted a bit wider ski for the cross-country applications so if you jump off of the trail you have a better feeling in loose snow and the ski will support the sled much better.”

SG: In what conditions will riders truly feel the biggest difference of riding a Ski-Doo with the RAS RX and Pilot RX package compared to the older RAX X and Pilot X?

DORMOY: “Everywhere! Honestly, in my opinion, that suspension is better everywhere. In corners on hard snow, when the trail is freshly groomed and it’s cold outside, you will feel it. The reaction of the ski leg, you will feel it with the new suspension for sure. In corners with soft snow, you will feel it in every condition. Even in a straight line, on bumpy trails or in racing-style cross-country, you will feel it as well. The steering stability. We also revised the shock calibration and everything – we’ve fine-tuned everything on the sled so you will feel it everywhere. It depends on your driving style and what you like, but I’m confident everyone will enjoy the improvement.”

SG: Now that the design has been publicly released, what about it makes you and your team most proud?

DORMOY: “We checked all of our goals on this project and overall we raised the riding experience on the G5. In the end, we are very proud to say that we have the best OEM sled to conquer the most challenging trail conditions with confidence. That last part is very important – with confidence. When you trust your sled, you connect with your sled.”

Editor’s Note: Every Snow Goer issue includes in-depth sled reports and comparisons, aftermarket gear and accessories reviews, riding destination articles, do-it-yourself repair information, snowmobile technology and more. Subscribe to Snow Goer now to receive print and/or digital issues.