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There are a number of obvious advantages with the single rail. First, the suspension is lighter by 11 pounds, compared to a twin rail design. Twin rail designs also hold more snow between the rails and crossbars, which adds to the overall weight when riding in loose snow. With the single rail, Ryan Thompson and his crew could report hardly any extra snow building up during hard use, which could easily mean 30-50 pounds less for the suspension to control, therefore a much quicker response from the air shocks as well as much less rider fatigue from the added weight. The original prototype monorail was fabricated and welded together from aluminum extrusions.
The production version is much more advanced. To save an additional 2 pounds the front is a magnesium casting that incorporates the front arm mount, front shock mount, limiter strap mount, idler wheel mount, and front anti-stab wheel mounts. The rest of the rail is extruded aluminum, but the two pieces are joined together by a space-age adhesive process. Welding the two pieces together would be dangerous, since magnesium is a fire hazard that is used in fireworks to give off nice glowing sparks. Since adhesive was used up front, it is also used for the brackets on the aluminum rail as part of the complete assembly procedure, eliminating all welding.
The suspension is mounted in the new Ascender platform. In this design the front drive axle is lowered 1.125 inches, which provides a larger tunnel clearance for the 3-inch lugged PowerClaw track. With the lower driveshaft, it gains a 9.7-degree flatter approach angle with the large 8-inch drive sprockets. The flatter approach angle not only reduces friction when the track hits the rail, but tests have shown that it more effectively compresses and packs the snow for better grip by the paddles. This allows the sled to come up on top of the snow faster than steeper angles that tend to churn the snow and sometimes, in loose conditions, actually promote track spin rather than gradually gripping the snow, leading to trenching.
¦ Alpha dog?
There are obviously many questions about the new design: Will the components hold up, will the drive sprockets be strong enough, will the tracks derail and break and so on? Naysayers are left standing on the sidelines, just as racers did when they first saw Bobby Unser’s IFS design, and most predicted it would break. Five years later they all had to have one to be competitive. The verdict is still out on just how well the Alpha One will perform in the spring when the snow goes from soft during the day to hard over night. Would the track bend and slide-out during these morning conditions and a stiffer twin-rail fair better? The AmSnow test crew felt this was an unfair question because on hard ice, nothing bites. Most riders wait until later in the day when the surface is softer again. The Western Mountain test crew all felt that the Alpha One performed better than twin rails in a lot of conditions, but a verdict will have to wait until a full season of testing in all conditions has been done.