I am about to build another piste ski - it will be 74mm underfoot, 182cm long, 17,5m radius (ash core, 2,5 - 15 - 2,5 profile, 300g/m² triax carbon below and above core, 300g/m² uni flax on top)
I am very satisfied how my piste skis carve and drift. The only thing I miss that factory race skis have is extreme egde grip on very icy conditions. I am not talking about carving any more, but drifted turns or hockey stops. I was wondering what I could do to achieve this.
My thoughts so far are:
Increasing the stiffness of the whole ski is not an option as it will be terribly hard to ski then
I actually think that the edge grip from the race skis acutally mostly comes from a very stiff area underfoot. When I do compare how my skis bend compared to factory skis, my skis bend more evenly along their length (thats why they carve very smooth). Factory skis bend more towards the tip and tail but less underfoot.
So my initial try would be to stiffen a length about 60-80cm underfoot - unless I get some good input here
I am unsure what to use to increase the stiffness. Uni, Biax, Triax, Quadriax?
not related to ski stiffness or the actual construction, but most race skis recommend somewhere around a 3/1 side/base edge bevel - and people sometimes use as high as 5 degrees on the side for slalom.
what bevel are you testing and have you tried re-tuning at various combos?
I always tune 87/1 (or 3/1). I tune regularly and precise (fine diamond at the end). I have a Völkl GS 183cm and a Völkl GS 193cm race ski to compare to my skis. The short one really is quite like a normal ski and relatively easy to ride. The 193cm is a monster that tires legs very quickly - I won't use that one for comparison.
The 183cm ski does not have the extreme edge grip on ice the 193cm has, but it is superb to my self-built skis. As the flex of the 183cm and my self-built ones are quite equal, it cannot be the flex really - so more uni carbon/glass/flax probably will not do the trick.
I will add more biax to the next build (I usually use carbon triax and uni flax for dampening) and check if the so increased torsional stiffness helps.
The Völkl skis use Titanium (only?) as reinforcements, which is quite different to ride to the carbon/flax combo. Maybe this also makes a difference...
I compared my self-built skis to the race skis - it is definitely the torsional stiffness that is stronger in the race skis. So, for my next skis, I will add some biax to the carbon triax and see how much that changes. Not sure yet how much additional biax to add (the carbon triax I use contains 200g/m² biax) and if I should add carbon again or go for glass.
As far as I understand, biax hardly makes the flex of the ski stiffer, right?
It’ll still make it stiffer but not by as much as having a 0 degree layer in the weave.
Most race skis use titanol (it’s the trade name for an aluminum alloy, not titanium), which adds dampening and torsional stiffness. That’s probably the missing ingredient in my opinion. The added damping will make the ski vibrate less on hard surfaces, increasing the grip. I suspect that the lightness of the carbon fiber compliments the weight of the titanol. Do your self made skis vibrate noticeably at speed when on ice?
Another option might be to use a more heavy wood in your core stringers. What wood are you using? For a race ski I’d expect something like ash to do really well because of its density.
Another option might be to use a heavier triax weave - maybe like a 20 or 22 oz fiberglass instead of carbon fiber.
Another less elegant option might be to keep the CF, get wider/thicker vds foil, and/or use it more liberally in your build somehow, in addition to the biax your considering adding. It won’t add to the torsional stiffness but would help with vibration, and the biax would add to torsional stiffness, but overall stiffness as well so maybe reduce core thickness by a couple tenths of a mm if you go that route to keep the lengthwise stiffness manageable. Of course, Im just guessing here.
Some manufacturers also try to add mass dampers to the tip of the ski.
But yeah most race skis have a layer or two of titanol married to the carbon fiber, which is technically the tried and true answer. There’s some pretty good info on working with the stuff on this forum. I can’t say I’ve built anything with titanol yet, but it’s a goal.
regarding dampening: This is the part I like most about my selfmade skis. The 300g/m² Flax uni on top works extremely great with the carbon. The skis are "quieter" under foot than all titanal skis I have ridden. They also do not vibrate on ice, they just "slip" more than the race skis.
Regarding the wood: I use ash for sportive skis always.
For this ski, I will not add too much biax I think. Either it will be 160g/m² glass biax or 100g/m² carbon biax. Or 350g/m² flax only on top - so many options If this does not help with the ice grip, I will re-build the ski with titanal.
If this does not help with the ice grip, I will re-build the ski with titanal.