1995 m10 vs xtra

Heading north on the four-lane into Eveleth, Minnesota, you could zip right past F.A.S.T.™, Inc. You'd look at the lake on the right and dismiss the brown barn-like building as being important in the history of snowmobiling. What has gone on inside that brown building has been historic…at least as far as snowmobilers should be concerned.
F.A.S.T.™, Inc., until a few years ago, was primarily a small Ski-Doo performance parts specialist. Owner, president and hall of fame racer Gerard Karpik used his past racing expertise and connections to scratch out a niche in go-fast "Ski-Dooing."

FROM BIKERS TO BILERS
As a cross-country racer, he learned the value of suspension. Racing in the ditches of Minnesota, North Dakota and Canada, he learned that while a strong engine can put you in front, a strong suspension will keep you there. As part of the Ski-Doo racing team when Bombardier was building Can-Am off-road motorcycles, Karpik also took the time to learn about shock absorbers, springs and suspension set-ups from the moto-cross engineering types at Bombardier. He made a connection between bikes and sleds and the action/reaction of shocks and springs and geometric angles. Look at the F.A.S.T.™ M-10 snowmobile suspension and you'll see that his self-taught course in suspension engineering was intensive and very successful.

While the M-10 is a new concept to snowmobiling, successful Karpik-designed suspensions have been around for quite a while. It was a Karpik-designed suspension on the Ski-Doo snocrosser of the early 1980s that dominated those early "pro" circuits. It has been a variant of that Karpik-designed suspension on both Ski-Doo and Lynx chassis that have helped Toni Haikonnen to be Finland's top snocross rider.

SUSPENSION REVOLUTION
There is a simplistic beauty in the M-10. It can be both an excellent competition suspension and an excellent trail-riding suspension. And there is another truth about the M-10 suspension. It has changed the sport for the better. Why do you think Polaris offers an Indy XTRA suspension system and why Bombardier offers a long travel touring suspension? Consumer demand, pushed by F.A.S.T.™'s M-10, insisted on it. The question consumers are putting to the four manufacturers is simple, "Why can't I have a sled with an M-10 ride?"

In reality, today's snowmobilers have to turn to F.A.S.T.™ in Eveleth, Minnesota, for an M-10 ride. No one else has it. A couple are getting closer, but as F.A.S.T.™'s president states, "The XTRA is where we started."

XTRA, SCHMXTRA?
If the M-10 is the best, how much better is it than the Polaris XTRA? What would happen if we took the first iteration of the world's best production snowmobile suspension system and compared it to the world's best snowmobile suspension set-up? Simply stated, we consider the M-10 suspension engineered by F.A.S.T.™ Inc. to be the best overall rear suspension that you can buy. We also feel the Polaris Indy XTRA single shock unit (now a dual shock unit) is the best unit available in a production sled.

It wasn't all that easy arriving at that conclusion. Like you, we've read a lot of hype about the M-10. Some of it seemed too good to be true …and probably was. We'd seen it. Had an idea of how it worked, but hadn't really spent any time on it.

With the M-10 garnering great press and snowmobilers buying up all the M-10s that F.A.S.T.™ could produce, the snowmobile manufacturers began to realize that snowmobilers wanted more. We had heard from the sled makers that suspensions would be the industry's next focus, but only F.A.S.T.™ seemed to be delivering on the promise.

SIDE BY SIDE
Now that the M-10 has secured an excellent reputation for being the best suspension you could ride, we are starting to see some movement from the sled makers. Last January, Polaris entered the picture with its new XTRA-14 suspension system and some really incredible numbers of inches of travel. We've tried that suspension, the single shock XTRA-14 with a claimed 13.6 inches of rear travel. We've also tried the second iteration of the XTRA (now referred to as the XTRA-12) with its dual shock rear suspension and claimed 12 inches of travel. Both iterations relied on a widened front suspension with internal floating piston gas shock and 10 inches of travel. The gas shocks in the XTRA-14 set-up were Fox-like Vector shocks. The shocks used in the second iteration are Fox® brand. The M-10 uses Fox® shocks throughout.

Now, as we stated in our September issue, the Polaris XTRA gives you the best ride of any production snowmobile. As we go to press you still can't buy a better riding production snowmobile than either the XTRA-equipped Indy XLT Special or Indy RXL. You can buy a better suspension and install it on virtually any of the popular sports and high performance snowmobiles built over the past three or four seasons. Is it worth it to you to pay the price of an M-10? If you can find an Indy XLT Special, you could buy the XTRA for $500 more than a standard XLT with the XC-100 suspension. That's a definite savings over shelling out $2,300 (1993 retail price) to upgrade a sled with the M-10. Is it worth it to upgrade? If you have a sled that you are going to ride a lot, we'd say you might give a new M-10 suspension serious consideration.

LEADING THE BAND
Now, then, as the old saying goes, it's not the size of the baton, but how you lead the band that counts. It applies in suspension lore. Not all suspension measurements are created equally. In olden days (pre-Arctco), vertical suspension travel was a simple thing to measure. Simply measure the distance between the rear suspension arm and the slide rail. Okay, it was a little more complex than that…but not much. In the 1970s Kawasaki skewed the measurement a titch when it included the bell crank movement of its suspension. It didn't matter and the measurement wasn't enough to save the Kawi brand.

Today, sled suspension travel is weird science, partly fact and partly fiction, designed to foster the impression that more is better. As we stated, it is how you lead the band that counts. Of course, if you're F.A.S.T.™, you also have the biggest baton.

Suspension guru Gerard Karpik, along with brothers David and Randy, won't disagree that Polaris' single shock XTRA-14 had a lot of suspension travel. If you measure metal to metal from the rear arm to the rail, the XTRA-14 moves 9.64 inches, the most of any production sled on the market. If you arrive at suspension travel by measuring the displacement of the rear idler at full travel, you get 12.4 inches. Again, it is the most of any production sled. The two shock XTRA-12 officially produces 12 inches of rear travel. A prototype of Ski-Doo's new long travel suspension gave a metal to metal reading of 8.9 inches. The M-10 provides 10.68 inches of travel when measured the old-fashioned way and 13.8 inches when measured the new-fashioned way.

'SEAT OF THE PANTS' TEST
Just before Labor Day we traveled to Eveleth, Minnesota, for a session of seat of the pants field testing and comparison of the M-10 in an Indy XLT and the Indy XTRA-14. Having ridden both the XTRA-14 and the XTRA-12, we prefer the original version but understand the advantage of the dual shock XTRA-12. The evaluation was conducted with F.A.S.T.™ technicians on hand and under the watchful eye of Gerard Karpik. Initially he had cause to worry. We are on record as being extremely impressed with the XTRA. We still are. We still believe it is the best riding suspension available in a production sled. And we were a bit apprehensive ourselves about the comparison. How would we tell the "King" that we didn't think F.A.S.T.™'s suspension was as good as the Polaris if that was our final impression?

We needn't have worried. The F.A.S.T.™ crew had outlined a course of about a mile in total length that ran the perimeter of a huge pasture and crossed over a small gravel pit. The grass was tall and wet enough from morning rain to keep the slide rails lubed. The plan was to ride one sled around the course at a sustained speed and then switch immediately to the other sled, riding it at a similar speed. Our speeds would start out at 20 miles per hour and work themselves up incrementally by 10 mile per hour bumps to 50 MPH. That was the plan and we stuck to it.

The course was mostly tall grass, weeds and ferns with some bare dirt here and there. We even had a muddy section or two to churn through to keep the slides wet. Since this was late summer and winter snows were at least a month away in this part of northern Minnesota, we had the advantage of getting a real "feel" for the terrain and the action…reaction…of the suspensions.

BOTTOM LINE
After a bit of testing, we realized a significant difference between the two suspensions. The M-10 has very little aftershock. If we had been comparing an XTRA to a C-7 or Cat ZR set-up, we probably wouldn't have noticed this difference. All conventional snowmobile suspensions are set up for a rising rate. In short, the suspension gets stiffer as the force of the bump progresses. That's an effective action. It's not an effective reaction. What happens is you get an after-effect, after shock, recoil, rebound, kick…whatever you want to call it. The harder you hit, the more progressively the suspension loads up and the harder it recoils giving you an aftershock or kick once you've actually come off the bump.

The M-10 mitigates this action. Karpik refers to the M-10's action as Advanced Ride Control Geometry. The suspension actually becomes more supple as the force of the bump progresses. By using up all of the shock and spring action, the movement dissipates more of the bump's force and leaves little or no recoil to come back and literally kick you in the butt.

"A snowmobiler really only cares about what he feels under his butt," Karpik states. "The actual number inches of suspension travel doesn't mean a thing if his bottom is getting beat up."

If you should bottom the M-10, and it can be done, the suspension is designed to release some of the force of the bump against the slide rail. When fully compressed, the spring and shock forces are vectored out to the rail. The rearmost Fox® shock in the M-10 uses a remote reservoir which provides better overall damping than a standard internal floating piston gas shock. In addition, the feeder line between the shock and reservoir acts as a relief valve when a really strong force is transferred through it. The expansion and contraction of the line further dissipates some of the force.

PERFECT COUPLING
The real secret to this suspension lies in the way the design "couples" the front arm to the rear arm. There is a symbiotic relationship between the two. When the M-10's front arm contacts a bump, the M-10's coupling action forces the rear arm to respond instantaneously. The result is to limit the angle between the rail and the bump as the rear arm crosses it. According to F.A.S.T.™, the flatter the angle is kept, the less secondary reaction ("kick") will be felt by the rider. The coupling devices are white plastic blocks that slide. They are located at the rear of the rail. In case you have thoughts about copying them, don't bother. It's a patented design. Optional blocks are available for custom tuning the M-10 for specific racing or trail conditions.

USER FRIENDLY
In addition to the blocks, the M-10 is a truly adjustable and user-friendly unit. The "Full Range Adjusters" refer to the lower rear shock attachments. By setting the adjuster at #1, the soft setting, the M-10 can accommodate a 100-pound rider. Moving the adjustment to #5 or the firmest setting results in a set-up that can accommodate 350 pounds of rider and gear. Moving the shock forward increases shock speed and results in firmer damping on both compression and rebound strokes. It also displaces the rear spring more. The adjuster is virtually infinitely variable and extremely easy to set.

ADVANTAGE: M-10
The harder we rode each suspension, the better they responded. The M-10 has the decided edge at low speeds and is also better at higher speeds. This was particularly true of the front suspension action. The harder we rode the XTRA, the better the front action became. To balance the XTRA, Polaris reworked the IFS to give it 10 inches of travel and a wider stance to compensate for the higher center of gravity you get with the taller XTRA rear unit. The stance was stretched to 43.5 inches versus the 40 inches of the standard unit.

The M-10 suspension we tested fit nicely in the Indy XLT chassis and kept the center of gravity lower than the XTRA. Up front, we found F.A.S.T.™ valved Fox® shocks with a slightly longer rod than the stock Indy IFS setup which gave us a matched ride front to rear. We felt that the M-10 match up worked exceptionally well. We give the overall advantage, front and rear, to F.A.S.T.™

SUCCESS STORY
Historically, keep these facts in mind. It is Karpik and the crew at F.A.S.T.™ who have shown the snowmobile industry how to get a great ride from virtually any snowmobile. That's a major accomplishment. In order to sell the M-10, F.A.S.T.™ had to make the M-10 work on Arctic Cats, Polaris Indys, steel chassis and aluminum chassis Ski-Doo models, and the Telescopic Strut Yamaha Vmax designs. A snowmobile manufacturer has to make its suspension work on only its own models.

In addition, the M-10 has been "out there" for a few years. Others have had a chance to see it, study it, measure it, test it, compare it, and try to better it. The M-10 is successful because it works better than anything else. One thing we know about snowmobilers, they know what they want and they'll buy it.

F.A.S.T.™'s M-10 was the quantum leap in suspension design. Snowmobilers know this. Demand has exceeded supply, but F.A.S.T.™ is gearing up…fast!

Going into the 1995 model year, we can see that the sled makers are aware that the M-10 is the wave of the future. Right now, only F.A.S.T.™ has the M-10. But, Gerard Karpik and his brothers are more than willing to share their suspension with any consumer who wants one. If you want a great ride from the first mile through the last mile of your trip - regardless of terrain, your riding style, your weight, or conditions - you'll want an M-10. We found the suspension was extremely easy to set-up, fully adjustable and if you have any questions, the M-10 owner's manual is extremely logical and easy to understand. Like the suspension, the owner's manual is top notch.

Now then, what did our exercise with the M-10 versus XTRA prove? For one thing, we know that there is a big difference in ride performance between a Polaris XTRA and any other production snowmobile, including an Indy with XC-100 rear suspension. Foremost, though, we know beyond a doubt that the quantum leap in suspension design and snowmobile ride and handling came from the M-10. It sets the standards.

If we were a snowmobiler who had recently purchased a 1995 Indy XTRA, we wouldn't be foolish enough to automatically discard the Polaris suspension in favor of the M-10. We're way too cheap for that.

However, if we owned anything else, yeah, we'd can the stock suspension and order up an M-10. The baton is bigger and you can really make the band play.

Suspension Mythology Explained
When it comes to snowmobile suspension talk, we often hear terms that make Greek and Klingon-speak seem like normal vocabulary. In an effort to lighten the load of suspension-speak, we offer these terms as defined by F.A.S.T.™

Advanced Ride Control - Geometry that decelerates shock and spring speed throughout compression travel and makes shocks very sensitive to sled speed. On return travel, the shock speed is increased, delivering a rising return rate. The result is excellent control of the "kick" and normal return forces of the suspension.
Center of Gravity - The point at which you could balance the mass of the vehicle on the point of a pin. A high center of gravity (C.G.) combined with a narrow ski stance translates into a "tippy" snowmobile. On a rider-less snowmobile, C.G. is effected by ski stance, track width, and engine placement. Rider placement and movement can alter C.G. positively and negatively.
Compression Stroke - The deflection of a shock absorber piston or spring created by pressing together, caused by a load which tends to press in from both ends, or from one end against a fixed end.
Crossover - The transition from one spring rate to another during compression travel.
Dual Rate Spring - Two different spring rates designed into a single spring. Generally a closely wound portion of the spring provides a soft area while a more loosely wound portion of the spring provides a firmer setting or rate.
Internal Floating Piston Shock -A high pressure gas shock absorber with its gas reservoir inside the main shock body. Oil is separated from the gas via an internal floating piston.
Rebound Stroke - The reaction of a shock absorber piston or spring created by removal or lessening of a load.
Remote Reservoir Shock - Separating a shock's nitrogen gas and oil via a floating piston or bladder in an external chamber (frequently mounted on the suspension slide rail).
SAG Settings - The difference in height of the sled's rear bumper from the sled's fully extended position to its drooped height with the rider seated on the snowmobile. Sag is used to control ride quality on rebound travel and is generally controlled by preloaded settings.
Ski Pressure - The amount of weight carried on the skis as a result of rear suspension tuning. Too little results in the sled's front end "pushing." Too much pressure results in the rear of the sled being "loose."
Spring Rates - The number of pounds of weight required to compress a spring one inch. A 250-pound weight deflecting a spring one inch would give you a spring weight of 250 pounds per inch.
Vertical Suspension Travel - The distance between the rear arm cross shaft and the slide rail.