Asymetry?

[Carbo]

I'm really interested in asymmetric sidecut skis, seems to make sense, but it would also seem that it's easier to f-it up by choosing bad dimensions than it is to get it right. Or the other way to look at is, before you go messing with a few hundred years of perfectly usable ski design you better have a good idea of what you're doing.

How have people here chosen their sidecuts and level of asymmetry? What logic went through your head?
Or if you haven't made your own, what logic *would* go through your head if you did?

I also really dig the asymmetric tails on the AhmaBCs. Having recently switched to commercial fat twins, I've caught my tails a lot. I've got a tight stance ingrained from many years on 200cm alpine bump skis.
Can you guys tell us how you decided on that particular shape, or did you just wing it?

Lastly, how do your skin attachments work with those tips and tails?

[Madriverglen]

i know what u mean ive destroyed the tails of all my skis in the bumbs and when i skate

[bigKam]

I'm really interested in asymmetric sidecut skis, seems to make sense, but it would also seem that it's easier to f-it up by choosing bad dimensions than it is to get it right. Or the other way to look at is, before you go messing with a few hundred years of perfectly usable ski design you better have a good idea of what you're doing.

i'm no expert and i'm not sure what the best design is for a ski. Kelvin, Kam and i are using a mixture of experience, guess work and science to design our skis. sometimes we use all three and sometimes we just simply guess. though there is over 100-years foundation for ski design, the availability of the information is very limited. this is one reason why we came up with the SkiBuilders' forum on this site -- to build a database related to ski design, share information and make it accessible. (there is a book by John Howe about the physics of skis and mechanics of skiing. i haven't read the entire book yet.)

as for the design of the sidecut in our asymmetric skis, we're picking the shape based on experience, and also where each ski is in relation to one another during a turn. the experience i'm talking about is skiing on other skis. we've asked ourselves what skis we like and then use their basic dimensions as a starting point. the asymmetric idea is not new. in fact, snowboard companies have used the design, as well as ski companies. whether it makes sense or not, that's something to debate. but what is cool is by being able to make skis at home, we can experiment. hopefully with enough iteration and analysis we can learn something useful. i'm sure there are pros and cons about the design, but for now, it's something we're investigating. experimenting is fun.

How have people here chosen their sidecuts and level of asymmetry? What logic went through your head?
Or if you haven't made your own, what logic *would* go through your head if you did?

during a turn, the outside edge of the inside ski is closer to the center of the turn, therefore we decided to make the outside-edge turning radius shorter. using the Salomon Pocket Rocket design as a starting point, we picked the 24 and 21 meter sidecuts. anyway, i think it's more complicated than that, and hopefully one of us will do some analysis and come up with some design rules. for now, we're just experimenting with the idea and it's fun. the skis work pretty well and they do feel different compared to traditional skis.

having said that, it would be nice to see what opinions others have related to asymmetric ski design. the discussion would benefit everyone i think.

I also really dig the asymmetric tails on the AhmaBCs. Having recently switched to commercial fat twins, I've caught my tails a lot. I've got a tight stance ingrained from many years on 200cm alpine bump skis.
Can you guys tell us how you decided on that particular shape, or did you just wing it?

we just guessed on the shape. the idea was to make sure that it was asymmetric enough to minimize scraping. to be more scientific, we could have tried to do a simulation or some analysis, but for now, we just wanted to test the idea. it seems to reduce the scraping, but it does look a bit awkward, especially when you're skiing them and staring at your tips. but different is cool! when i get some time i'll post a writeup for the design of the Ahma BCs. stay tuned.

Lastly, how do your skin attachments work with those tips and tails?

we cut a notch in the tail. i'll post a photo soon.

[bigKam]

here's a picture of the notch cut in the tail of the Ahma BCs for securing climbing skins:



notice that the ABS topsheet material is prone to chipping and peeling. click here to read the thread on ABS topsheet material.

[RichVH]

Hi this has been bugging me so I thought I'd bring it up to see what opinions are out there. Firstly I snowboard, but I'm looking to design some ski's for the missus so forgive me if I'm way off the mark.

I've been looking through the forum for some info about asymmetric sidecut skis, it makes sense in my head to have a larger radius on the outside edge and a smaller radius on the inside.



Would I be right in saying that the difference between the two radii would be the stance width of the person who would be using the skis? If I decided on the sidecut radius of one side of the ski, lets say i decide i want a 24m radius on the inside sidecut which would be my larger radius could I then take the stance width of the person I'm making the skis for eg. 50cm and subtract that from the larger radius which would give me a radius for the outside?... so 24-0.5= 23.5 or is it such a minimal difference that it has no effect?

[PTTR]

In my opinion it is a little bit more complicated. The skiis don't turn like that. They turn depending on the amount of pressure/flex/sidecut/grip in the snow.

Most people have a harder time putting pressure on the upper edge, specially telemarkers. A shorter radius could compensate for that. 0.5 meters would not be noticable I think. I would go for 3-4 meter difference if in the 20 meter spectrum.
If your technic is perfekt you should be able to put equal amounts of pressure on boths skis and don't have a problem.

[Dr. Delam]

You are correct that the inside ski will need a tighter turn radius in general. The problem is that ski turns are dynamic and unless you just always ski with your feet together old school style, your stance width changes as well as how far the ski in put on edge and flexed.



And yes, I don't think anyone would notice the difference between a 23.5 radius and 24.

[skidesmond]

I had given this a lot of thought last year as well, knowing that the inside ski is actually skiing a shorter radius. This would basically give you a left and right ski. It makes more sense on paper than in practice.

I've made skis that were asymmetrical by mistake because the bases warped. They were off in the middle by maybe 3-4mm at boot center. They didn't ski well. The tip area always seem to want to catch or not release at the right time. Even switching the skis to the opposite feet didn't help.

PTTR - you make a good point about the inside ski pressure. Most skiers do have a difficult time getting adequate pressure on the inside ski. It a relativity new idea (last 10+ years or so) with advent of the shape ski where the "new" inside ski imitates the turn. It's a strange feeling at first and takes some getting use to.

[veguis]

Serge Dupraz has thought of that, I'm not sure if it is correct or just a trick to sell more skis, in a couple of weeks I will try these skis.
You could take a look of the d2 skis, the idea it is interesting.
http://dupraz-skis.com/

[skidesmond]

It's an interesting theory. I'd like to hear how they ski.

[petemorgan(pmoskico)]

cooooooool

[tufty]

Coupla relatively interesting sidecut-related vids from Sean at Donek.

[skidesmond]

Check out the video http://dupraz-skis.com/infos-90-Decouvrir_les_D2.html

I think this is why I didn't like my asymmetrical skis, notice the extension of the up hill ski when he skis, that feels very weird like you're about to do the splits. Not sure how much he is making that happen and how much the ski is making that happen. Also my asymmetrical skis were a traditional shape, not like his. Maybe that makes a difference too, IDK.

Skis and skiing techniques are always evolving, maybe we'll all be doing that in a couple years.

[MontuckyMadman]

this is an asym BBR.
sucks.
maybe good for frogs.

[sammer]

this is an asym BBR.
sucks.
maybe good for frogs.

NOT for treefrogs though!