
Originally Posted by
ZomblibulaX
Not all base material is created equal, and not all bases have the same potential to become fast. As was said above, seemingly small things like contamination can make a huge difference.
As far as base material, the sintered polyethylene comes in big rolls, and typically the fastest material will be around the middle of the roll. So that's usually what gets chopped up for race skis, while the ends turn in to more budget-oriented skis, and the rest of the models get what's in between. There's a not insignificant amount of variance in porosity/density/hardness/etc. and it makes a big difference on snow.
Color makes a big difference in glide, durability, and how clean your structure comes out. Clear bases are typically harder than black, which is why they started doing split bases on race skis back in the day, and you still see it today. (Harder base at the tip of the ski because the snow is colder/less affected by the ski gliding across it, softer material in the back of the ski where the snow has melted and the ski is gliding on a film of water under the base). Some techs still wax slightly colder in the tip than the tail to accommodate the difference in the snow temp and water content, especially in speed disciplines and speed skiing. Hardness of the base material helps determine the breakaway point, which is the temp at which the ski begins to glide on the snow. So clear bases can be faster in cold, new, and dry snow, where abrasion resistance is important because the sharper dendrites of the snow crystals cause excess drag on the base. Black bases can be faster in warmer/wetter/older/machined snow conditions where the snow has transitioned and the water content has increased. But that's all before you even take in to consideration prep, structure, wax, contaminants, et al.
Structure can make a massive difference depending on the moisture content of the snow, the shape and condition of the snow crystals and the moisture potential in the snow. Weight and speed also play a big factor, because a skier weighing 40 kg and topping out at 50 kph is going to affect the snow under the ski FAR less than a skier weighing 90 kg going 120 kph. So a bigger skier will need a coarser structure designed to move more water, while a lighter skier will need a lighter, finer structure designed to reduce dry friction or drag. This can mean changing the inclination of the pattern slightly to change how quickly the water moves out to the edges, just speeding up the feed on the same structure to extend the "grain" of the pattern, or a completely different grind for the same snow conditions depending on the discipline.
Bright solid colored bases are straight up slower. I will die on this hill if I must. Solid color bases other than black do not finish as cleanly when grinding, don't absorb wax as well, and don't retain wax as well. I think it has to do with the dyes making the material softer and therefore less likely to cut cleanly when grinding, and more likely to fuzz up from skiing.
And even if you grind your skis exactly the same, use the same wax melted at the same temp with the same saturation, let it cool for the same amount of time, and scrape it the same, the brushing can make a huge difference in glide properties. For instance, finishing with a nylon brush will leave a very thin sheen of wax on the base, which is great for softer waxes in old/wet/transformed conditions, while finishing with a horsehair brush will pull more wax out of the structure and leave a "drier" finish for performance in new/dry/cold snow where reducing drag is paramount.
Basically, your skis all feel different because they are all different, even if you prep them the same. But yes, almost any base can be made relatively fast, some just take more work for certain conditions. Just wax your skis a bunch and they'll all be pretty damn quick. You don't even need fancy expensive wax, just do it a lot.
And purple bases are always slow.
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