I did also some test on binding mounting position and tip diving.
Usually with narrow skis (90-70-80) I have to sit on the back, to avoid tip diving. Fat skis are supposed to have a better behaviour in soft snow.
What is important is not just the overall surface but the difference between the front surface (the ski area between the tip of the boot and the beginning of the shovel) and the back surface (the area between the heel and the tail). The larger the difference, the more pressure you can put on the fornt part of the skis without diving.
The surface difference depends of course on the side-cut, on the ski length and on the binding position.
Narrow skis have about 140/160 cm2; my first skis (119-101-106) were very good in powder, no tip diving at all and they had 310. On the 2nd pair I made (145-120-130) I mounted the bindings quite in the centre, and I had to sit back sometimes, then I moved the binding 3cm backward, and it was much better: when I calculated the surface difference I found it changed from 135 to 210. I think that the Volkl Sanouk, mounting the binding as marked on the skis, is at about 280.
I would say that 200/250 is the best for powder skis.
Here you can find more info: http://isuisse.ifrance.com/Tromso/aeg/AEG.htm
Binding position
Moderators: Head Monkey, kelvin, bigKam, skidesmond, chrismp
hi davide,
very nice and informative site you have. i've never measured/calculated the surface area of my skis before but i'm interested in your thoughts about the surface differences and their relation to tip dive. my first pair of skis (The Whites) tip dive a lot in the powder. i'll have to measure the surface areas of them and see if my ratios fit into your categories.
by the way, what's the reasoning for the plywood construction cores? how do they feel compared to the traditional vertically laminated cores?
very nice and informative site you have. i've never measured/calculated the surface area of my skis before but i'm interested in your thoughts about the surface differences and their relation to tip dive. my first pair of skis (The Whites) tip dive a lot in the powder. i'll have to measure the surface areas of them and see if my ratios fit into your categories.
by the way, what's the reasoning for the plywood construction cores? how do they feel compared to the traditional vertically laminated cores?
- Kam S Leang (aka Little Kam)
The reason to use plywood, is that I could find high quality birch plywood very easily in a Brico-something shop. On the other hand, good quality wood for vertically laminated core was more difficult to find. Then I have no machine to make the bottom side of the core flat. Finally I cut four plywood sheets, 190, 160, 120 and 80cm long, then I glue them one on top of the other. I need the router only to machine few millimetres of wood, to make the ski smooth: my router is not very powerful (I paid it 30euros), so I could not machine a full tick core.
Before making skis I made a couple of longboard (long skateboard) about 1.2m long. Then I said: OK, I make it longer and slightly thicker, and I will have a ski. I know few snowboards are made like this.
I do everything by hand, the only electric machine I use is a router to make the tip and tail thinner.
I actually I have no idea about differences in performances: you know, you should build two skis, same shape, same size, same amount of fibre, just different core, then you can say something.
Anyway I am very happy with my ski, even if I have some problems with the poplar plywood: it is quite fragile, and it breaks easily; I could fix the skis and I am still using them. Probably I will use only birch and ash in the future. Maybe I will try balsa…
I can probably buy some vertically laminated wood core from small ski/snowboard manufacturer, so it is not excluded that I will make a "standard core" ski in the future.
Before making skis I made a couple of longboard (long skateboard) about 1.2m long. Then I said: OK, I make it longer and slightly thicker, and I will have a ski. I know few snowboards are made like this.
I do everything by hand, the only electric machine I use is a router to make the tip and tail thinner.
I actually I have no idea about differences in performances: you know, you should build two skis, same shape, same size, same amount of fibre, just different core, then you can say something.
Anyway I am very happy with my ski, even if I have some problems with the poplar plywood: it is quite fragile, and it breaks easily; I could fix the skis and I am still using them. Probably I will use only birch and ash in the future. Maybe I will try balsa…
I can probably buy some vertically laminated wood core from small ski/snowboard manufacturer, so it is not excluded that I will make a "standard core" ski in the future.
yeah i really want to try making a horizontally laminated core but finding the wood to do it seems difficult. all the thin sheets of maple, birch, etc. that i've seen already come laminated as a thick sheet of plywood. maybe this would work? did you have problems when using your router to make the tips/tails thinner? i sent a piece of plywood into my planer today and after a few runs the machine started ripping the top layer of wood apart and came off in huge chunks.
- Kam S Leang (aka Little Kam)
The thick plywood has only half of the layers in the longitudinal direction. While I glue 4 sheets of 3 layers plywood (4mm thick): in a sheet, the top and bottom layer have the same fibres orientation, so if I glue 4 sheet one on top of the other, I end up with 8 longitudinal layers and 4 transversal layers, that is stiffer than a 12 layers plywood (6 longitudinal and 6 transversal layer). The woodcore is 16mm thick at the centre and 4mm thick at the tip and tails. It is quite thick and solid, so I have to put few glass to make it stiffer. That's why my skis are quite light: wood has a better specific Young modulus than fiberglass.
I am sending you few pics by email.
I had no problem in machining the plywood; I fix the board on the bench with few screws and do it. As I told you, my router is really poor, so Iif I try to machine thick wood quickly, it slows down.
I know M. Tardy in the French Alps is making skis just with wood, no reinforcement at all: I want to try that as well.
http://www.skipass.com/carnets/carnet.p ... 27&art=164
http://www.skis-bois-tardy.com/
http://www.skihorizon.com/fr/magazine/skisenbois.asp
(just train your French…)
I will probably try to do something like that.
I am sending you few pics by email.
I had no problem in machining the plywood; I fix the board on the bench with few screws and do it. As I told you, my router is really poor, so Iif I try to machine thick wood quickly, it slows down.
I know M. Tardy in the French Alps is making skis just with wood, no reinforcement at all: I want to try that as well.
http://www.skipass.com/carnets/carnet.p ... 27&art=164
http://www.skis-bois-tardy.com/
http://www.skihorizon.com/fr/magazine/skisenbois.asp
(just train your French…)
I will probably try to do something like that.