Questions
Moderators: Head Monkey, kelvin, bigKam, skidesmond, chrismp
Questions
I am new to designing skis and have a few questions that I thought you guys could help me with. First of all, I've been looking around and am having trouble deciding how stiff my skis should be. I am only 140 lbs but the skis will be used for higher speeds. Also how much of the length of the ski should be put into non-running length aka tip and tail. Thanks for the help and I think this is a great site and look forward to contributing more in the future.
Welcome Sam,
We'll all have varying opinions regarding your questions, but here's mine.
I say soft, wide skis for soft snow, and firm, narrower (I like mid-fats) skis for firm snow. I want my soft snow ski to float well and have a soft enough flex that it will decamber into a nice, deep flex arc for the turns. A stiff ski in soft snow won't flex into an arc, so it won't turn well... I'm not using my edges to turn in soft snow, I'm using the ski base to turn.
On firm or hard snow, I don't need to float... I need to carve with my edges. So, I want a narrower ski so I can be faster edge to edge and also to get some edge pressure to to the tip and tail edges so they'll hang in the turn... that happens better if the ski is narrower and has a stiffer flex. On firm snow, a narrower ski is easier on my knees, ankles, and leg muscles. If I ski on a wide ski on hard snow even for 2 or 3 hours, my legs really feel it.
If you are 140 lbs. and wanting to go fast, my question to you would be, "Do want to go fast down deep powder faces, or fast down groomed packed downhill runs?". We don't really have an objective method (yet) for telling you just how stiff you should build a ski for a specific purpose. I'd say, use the info that you get from the forum and from the site and make your best guess on core materials and core thickness. Then, build 'em, ride 'em, and decide whether you want your next pair to be softer or stiffer.
The answer to your second question kinda depends on whether you're going with twin tips or not, and how round or pointy your tips are. My nose tip takes up about 18cm of the ski length, but I use a fairly long, pointy tip for better climbing skin retention. A more rounded tip would take up much less length.
Here's my usual advice: take your time, read everything on the site and forum, keep it fun.
G-man
We'll all have varying opinions regarding your questions, but here's mine.
I say soft, wide skis for soft snow, and firm, narrower (I like mid-fats) skis for firm snow. I want my soft snow ski to float well and have a soft enough flex that it will decamber into a nice, deep flex arc for the turns. A stiff ski in soft snow won't flex into an arc, so it won't turn well... I'm not using my edges to turn in soft snow, I'm using the ski base to turn.
On firm or hard snow, I don't need to float... I need to carve with my edges. So, I want a narrower ski so I can be faster edge to edge and also to get some edge pressure to to the tip and tail edges so they'll hang in the turn... that happens better if the ski is narrower and has a stiffer flex. On firm snow, a narrower ski is easier on my knees, ankles, and leg muscles. If I ski on a wide ski on hard snow even for 2 or 3 hours, my legs really feel it.
If you are 140 lbs. and wanting to go fast, my question to you would be, "Do want to go fast down deep powder faces, or fast down groomed packed downhill runs?". We don't really have an objective method (yet) for telling you just how stiff you should build a ski for a specific purpose. I'd say, use the info that you get from the forum and from the site and make your best guess on core materials and core thickness. Then, build 'em, ride 'em, and decide whether you want your next pair to be softer or stiffer.
The answer to your second question kinda depends on whether you're going with twin tips or not, and how round or pointy your tips are. My nose tip takes up about 18cm of the ski length, but I use a fairly long, pointy tip for better climbing skin retention. A more rounded tip would take up much less length.
Here's my usual advice: take your time, read everything on the site and forum, keep it fun.
G-man
If you have some skis that you like then try a point load test to see how much they deflect as a gross measure of stiffness. You can then use the flex predictor spreadsheet to work out a basic core profile that will match your ski deflection. You can then get more specific by deciding that you like a stffer tail or tip and tweaking things a bit.
I believe that somewhere on this forum there is a graph with a load of ski flex profiles that have been measured, If you like one of these skis then you can use the spreadsheet to design a core to mimic these graphs.
B.
I believe that somewhere on this forum there is a graph with a load of ski flex profiles that have been measured, If you like one of these skis then you can use the spreadsheet to design a core to mimic these graphs.
B.
thanks g-man. your answer also helped me a bit 
i juste asked myself some questions about the effect of the stiffness on the characteristics of a ski.
so i thought about a softer flex for powder. but how are things with tip/tail-stiffness?
somwhere i recently read that powderskis have a "softer tip". but i`m not sure if they just mean the tip-section (the first few centimetres of the effective edge) or really the TIP... can you also say something about that?
i juste asked myself some questions about the effect of the stiffness on the characteristics of a ski.so i thought about a softer flex for powder. but how are things with tip/tail-stiffness?
somwhere i recently read that powderskis have a "softer tip". but i`m not sure if they just mean the tip-section (the first few centimetres of the effective edge) or really the TIP... can you also say something about that?
plywood freeride industries - go ply, ride wood!
plywood,
Your question may stir up a lot of different responses. Again, here's mine.
For my skis, I primarily design in whatever parameters I think will result in the most consistent circular flex arc. This is because, for me, skiing is all about the turn. The turn is best if it forms a portion of a true circular arc (one that, if completed 360 degrees, would form a round circle). A ski will turn in a circular arc if it flexes in a circular arc. If the flex arc of the ski is not circular, the ski must be forced to turn in a true circular arc.
So, regarding things like 'softer tips for better float' and 'stiffer tails for better release from a turn (or better hold in a turn)', I think it's mostly industry hype to get people to buy a product. Tips that are too soft and tails that are too stiff will only result in a flex arc where different portions off the ski are wanting to head toward different destinations. If a ski is designed correctly, the tips will float just fine and the tails will release just fine... and the flex arc will be circular. As an example, if you do happen to feel that you need better tip float in soft snow, think about increasing the difference between the tip and tail widths. A narrower tail width moves the waist of the ski further towards the tail. Because the ski boot pressure center should be mounted at the waist of the ski, this gives more surface area to the portion of the ski in front of the boot... more surface area equals more float. Keep in mind, though, that as you change the shape of a ski in such a way that it moves the waist forward or back, you'll also have to make adjustments in your profiling to keep the flex arc circular. Also for more tip float, you could consider a reverse side-cut design (see past posts by greg).
Some readers on the forum my be getting weary of my "circular flex arc" discussions. I know that I can sound a bit obsessed at times. As I've said before, after skiing on a ski that truely has a circular flex arc, then skiing on other skis that don't have it, I can readily feel different parts of the other skis fighting one another for the track of the turn. I, then, can't wait to get off of them and back onto my smooth turning, circular flexing skis.
I really think that the industry has made ski design into something much more complicated than it needs to be. A big part of the problem is this whole thing of needing to come out with something each year that is newer and better than the competition. Look at this year's K2 Pontoon. It's a pretty wild design, but I'm betting it doesn't ski for crap. But it's new and different, so the rest of the industry will try to follow with something 'better' and even more wild. Oh well, let 'em do their thing... and we'll do our's... we're ski builders!
G-man
Your question may stir up a lot of different responses. Again, here's mine.
For my skis, I primarily design in whatever parameters I think will result in the most consistent circular flex arc. This is because, for me, skiing is all about the turn. The turn is best if it forms a portion of a true circular arc (one that, if completed 360 degrees, would form a round circle). A ski will turn in a circular arc if it flexes in a circular arc. If the flex arc of the ski is not circular, the ski must be forced to turn in a true circular arc.
So, regarding things like 'softer tips for better float' and 'stiffer tails for better release from a turn (or better hold in a turn)', I think it's mostly industry hype to get people to buy a product. Tips that are too soft and tails that are too stiff will only result in a flex arc where different portions off the ski are wanting to head toward different destinations. If a ski is designed correctly, the tips will float just fine and the tails will release just fine... and the flex arc will be circular. As an example, if you do happen to feel that you need better tip float in soft snow, think about increasing the difference between the tip and tail widths. A narrower tail width moves the waist of the ski further towards the tail. Because the ski boot pressure center should be mounted at the waist of the ski, this gives more surface area to the portion of the ski in front of the boot... more surface area equals more float. Keep in mind, though, that as you change the shape of a ski in such a way that it moves the waist forward or back, you'll also have to make adjustments in your profiling to keep the flex arc circular. Also for more tip float, you could consider a reverse side-cut design (see past posts by greg).
Some readers on the forum my be getting weary of my "circular flex arc" discussions. I know that I can sound a bit obsessed at times. As I've said before, after skiing on a ski that truely has a circular flex arc, then skiing on other skis that don't have it, I can readily feel different parts of the other skis fighting one another for the track of the turn. I, then, can't wait to get off of them and back onto my smooth turning, circular flexing skis.
I really think that the industry has made ski design into something much more complicated than it needs to be. A big part of the problem is this whole thing of needing to come out with something each year that is newer and better than the competition. Look at this year's K2 Pontoon. It's a pretty wild design, but I'm betting it doesn't ski for crap. But it's new and different, so the rest of the industry will try to follow with something 'better' and even more wild. Oh well, let 'em do their thing... and we'll do our's... we're ski builders!
G-man
thanks for the explaints. the thing with the circular flex arc sounds very logical.
so...for the perfect flex arc you would need a parabolic profiled core, am i right?
i think there could be done a lot of researches about the flex-thing. on the slopes and on hardpack i totaly agree with you, a perfectly circular flex arc is the best thing. but for soft snow...? i think it would be very interesting to make some tests, which kind of flex floats the best on soft snow, what happens during a turn excately etc. (well... we "know" kind of what happens, but i`m in doubt if this is really the full "thruth")
by the way: K2 are not the only one with the combination of inverse and "normal" sidecut on a ski, like it`s designed on the pontoon. i just saw some pictures of an armada ski that has overall an inverse sidecut but in the middlesection the sidecut is normal. and i really don`t think the industry just made these skis because they have to bring something new. look at the spatulas: the are kind of the first skis with inverse sidecut. the pontoon and the armada ski are now the next step: the spat`s have to be great for pow, but unrideable on hardpack - and that`s the reason why some dudes "applied" normal sidecut in the middle. that`s the way i look at these things - they are progression
so...for the perfect flex arc you would need a parabolic profiled core, am i right?
i think there could be done a lot of researches about the flex-thing. on the slopes and on hardpack i totaly agree with you, a perfectly circular flex arc is the best thing. but for soft snow...? i think it would be very interesting to make some tests, which kind of flex floats the best on soft snow, what happens during a turn excately etc. (well... we "know" kind of what happens, but i`m in doubt if this is really the full "thruth")
by the way: K2 are not the only one with the combination of inverse and "normal" sidecut on a ski, like it`s designed on the pontoon. i just saw some pictures of an armada ski that has overall an inverse sidecut but in the middlesection the sidecut is normal. and i really don`t think the industry just made these skis because they have to bring something new. look at the spatulas: the are kind of the first skis with inverse sidecut. the pontoon and the armada ski are now the next step: the spat`s have to be great for pow, but unrideable on hardpack - and that`s the reason why some dudes "applied" normal sidecut in the middle. that`s the way i look at these things - they are progression
plywood freeride industries - go ply, ride wood!
plywood,
A "perfect flex arc' doesn't necessarily need to come from a parabolic shaped ski. It can come from any shape of ski... even a ski with inverse sidecut. The arc charactoristics mostly happen as a result of the profile... where it's thick and where it's thin... with some effects, of course, from varying width.
My main point wth a soft snow ski is that the shape can be just about any thing because the edge doesn't really 'engage' the snow... the base is what we're riding on in soft snow. So, how the base flexes is mostly what is important. Personally, I quite like the theory behind the inverse sidecut ski... I just haven't built and skied one yet... but, that's about next on my list. The reason I like the inverse sidecut idea is that, if the waist of the ski is wider and floats better, then the tip is going to float better. I still believe it will perform better with a circular flex arc than without. And even though the inverse sidecut is a realitively new concept, it's still pretty basic and straight forward, and probably a great move forward for the dedicated soft snow ski. I still think that the use of different normal and inverse side cuts on the same ski is just making it more difficult to acheive a good flex arc, without adding performance otherwise. I could certainly be wrong. It'll be interesting to see what I'm saying a few months from now.
G-man
A "perfect flex arc' doesn't necessarily need to come from a parabolic shaped ski. It can come from any shape of ski... even a ski with inverse sidecut. The arc charactoristics mostly happen as a result of the profile... where it's thick and where it's thin... with some effects, of course, from varying width.
My main point wth a soft snow ski is that the shape can be just about any thing because the edge doesn't really 'engage' the snow... the base is what we're riding on in soft snow. So, how the base flexes is mostly what is important. Personally, I quite like the theory behind the inverse sidecut ski... I just haven't built and skied one yet... but, that's about next on my list. The reason I like the inverse sidecut idea is that, if the waist of the ski is wider and floats better, then the tip is going to float better. I still believe it will perform better with a circular flex arc than without. And even though the inverse sidecut is a realitively new concept, it's still pretty basic and straight forward, and probably a great move forward for the dedicated soft snow ski. I still think that the use of different normal and inverse side cuts on the same ski is just making it more difficult to acheive a good flex arc, without adding performance otherwise. I could certainly be wrong. It'll be interesting to see what I'm saying a few months from now.
G-man
Look at the Drake Powderworks Lotus 138 too.plywood wrote:by the way: K2 are not the only one with the combination of inverse and "normal" sidecut on a ski, like it`s designed on the pontoon. i just saw some pictures of an armada ski that has overall an inverse sidecut but in the middlesection the sidecut is normal.
------------------Take nothing I say as expert advice------------------