If this is your first visit, be sure to check out the FAQ by clicking the link above. You may have to register before you can post: click the register link above to proceed. To start viewing messages, select the forum that you want to visit from the selection below. |
|
|
Thread Tools | Display Modes |
#1
|
|||
|
|||
Usual wax pocket theory seems wrong...
The usual way of approximately locating the wax pocket of a classical
ski is to stand on both skis, equally, and slide a paper under them. Where the paper binds is the outer limits of the pocket. Official doctrine says the wax pocket keeps the kick wax off the snow when gliding or doublepoling. No, it doesn't! It only works for 2-footed gliding and part of doublepoling. It seems to me that the best wax pocket would be one where the kick wax is off the snow when ALL your weight is on one ski --- that's the condition in which MOST gliding occurs. It then seems that the camber should be designed to collapse only when one kicks or steps off of the ski, putting MORE than 100% of body weight onto the ski. With the way my skis are now when I glide while diagonal striding I'm contacting the snow and causing friction with about 50% of my kickwax zone. Only when we use the klister zone is all the kickwax off the snow during the diagonal stride glide. I'm thinking that all classic skis should have wax pockets that function like a klister zone. Klister skis should just have higher pockets because klister is thicker. So, what am I missing? I suppose I'm missing the possibility that lightly weighted kickwax works like a glide wax. ? Seems unlikely. Another angle is that a ski track isn't like a floor. ...Then again many ski tracks are firm like a floor. Given the irregularites of a track it almost seems like a kickzone should be higher off the ground, yet still collapse easily with the amount of pressure a kick generates. Maybe a kick doesn't generate more than bodyweight? Maybe kickwax doesn't cause friction when it's moving/gliding and only works when it STOPS. Unlikely. Kickwax causes lots of friction. But maybe if kicking isn't more than bodyweight then we just have to put up with this friction? Anyway, if there's a difference between the weighting of a ski when we glide on it while diagonal striding and when we kick on it then the ski-makers should isolate that difference and build their kickzone around that. ...So it offhand seems to me. --JP |
Ads |
#2
|
|||
|
|||
Usual wax pocket theory seems wrong...
On Mar 26, 11:38*am, jeff potter wrote:
The usual way of approximately locating the wax pocket of a classical ski is to stand on both skis, equally, and slide a paper under them. Where the paper binds is the outer limits of the pocket. Official doctrine says the wax pocket keeps the kick wax off the snow when gliding or doublepoling. No, it doesn't! It only works for 2-footed gliding and part of doublepoling. It seems to me that the best wax pocket would be one where the kick wax is off the snow when ALL your weight is on one ski --- that's the condition in which MOST gliding occurs. It then seems that the camber should be designed to collapse only when one kicks or steps off of the ski, putting MORE than 100% of body weight onto the ski. With the way my skis are now when I glide while diagonal striding I'm contacting the snow and causing friction with about 50% of my kickwax zone. Only when we use the klister zone is all the kickwax off the snow during the diagonal stride glide. I'm thinking that all classic skis should have wax pockets that function like a klister zone. Klister skis should just have higher pockets because klister is thicker. So, what am I missing? I suppose I'm missing the possibility that lightly weighted kickwax works like a glide wax. ? *Seems unlikely. Another angle is that a ski track isn't like a floor. ...Then again many ski tracks are firm like a floor. Given the irregularites of a track it almost seems like a kickzone should be higher off the ground, yet still collapse easily with the amount of pressure a kick generates. Maybe a kick doesn't generate more than bodyweight? Maybe kickwax doesn't cause friction when it's moving/gliding and only works when it STOPS. Unlikely. Kickwax causes lots of friction. But maybe if kicking isn't more than bodyweight then we just have to put up with this friction? Anyway, if there's a difference between the weighting of a ski when we glide on it while diagonal striding and when we kick on it then the ski-makers should isolate that difference and build their kickzone around that. ...So it offhand seems to me. --JP Dear Jeff: First of all, remember back to when we skied on wooden skis. Okay, I'm that old. Anyway, one waxed the entire pine-tarred ski bottom with kick wax. So, yes, well chosen kick wax will glide. If you've taken beginning physics, it's the difference between the static and dynamic coefficients of friction that allow both kick and glide, if you've chosen well. That being said, of course there is a difference between our modern glide wax and kick wax, and the less kick wax one can get away with, the faster the glide can be. Several of our Michigan Cup races this year had folks "classic" skiing on skate skis, to good effect. ( I hate you, Chip!) I watched the World Cup Classic sprint from Canmore last year, and all of the podium finishers went with skate skis. How they're able to double pole up those steep climbs (I've been there!) is beyond me, but they blew away the field on the flats and descents. The last pair of classic skis I had ground by Mark Wachter also have three zones marked as to height of the ski surface off of the snow, I think in tenths of millimeters. You could probably use the shortest zone in all hard tracks, whether hard wax or klister, because the snow won't shear. In soft track with fresh snow, a longer kick zone kicks on a longer area of snow, and therefore won't shear away and slip. Gotta go. . . Randy Bladel |
#3
|
|||
|
|||
Usual wax pocket theory seems wrong...
Jeff,
How many pairs of skis do you have? It seems you're constantly having problems with your skis. I think that you should contact a very high end dealer in skis -- say something like Boulder Nordic Sport -- and just buy a small number of pairs of skis that fit you exactly right and be done with your troubles. At least you can get some racing style classic skis that are near perfect like that. |
#4
|
|||
|
|||
Usual wax pocket theory seems wrong...
I've found that the best shops or ski fitters consider the
stand-on-the-ski test to be useless at best. Rather, in addition to visually and by feel evaluating how a pair closes by hand - you can learn a lot that way - they employ a well-engineered flex tester. The idea is to measure how much weight (relative to the skier's) and force it takes (relative to their kick) to get the ski's camber closed or in the glide position. For instance, starting at the beginning, if a Fischer classical ski measures 44.5, +4, .40, if I've got it right that means the ski takes 44.5 kg to close to .20mm (two thin layers), 4 more kg to close it to .10 (the "finish," standard measure of ski closed), and the half-weight camber height (open gliding) is .40mm. From there, they can work up and down the center of the ski to get exact measurements for degree of opening in the glide position (higher in the middle, less toward front and back). That gives you a theoretical wax pocket and how much wax to put there. Then you have to take those measurements out on the snow, preferably having waxed a bit longer, and see how it wears (variations per conditions, of course). For a good explanation, see http://www.caldwellsport.com/ski-ser...ex-evaluation/, and the pdf. Gene jeff potter wrote: The usual way of approximately locating the wax pocket of a classical ski is to stand on both skis, equally, and slide a paper under them. Where the paper binds is the outer limits of the pocket. Official doctrine says the wax pocket keeps the kick wax off the snow when gliding or doublepoling. No, it doesn't! It only works for 2-footed gliding and part of doublepoling. It seems to me that the best wax pocket would be one where the kick wax is off the snow when ALL your weight is on one ski --- that's the condition in which MOST gliding occurs. It then seems that the camber should be designed to collapse only when one kicks or steps off of the ski, putting MORE than 100% of body weight onto the ski. With the way my skis are now when I glide while diagonal striding I'm contacting the snow and causing friction with about 50% of my kickwax zone. Only when we use the klister zone is all the kickwax off the snow during the diagonal stride glide. I'm thinking that all classic skis should have wax pockets that function like a klister zone. Klister skis should just have higher pockets because klister is thicker. So, what am I missing? I suppose I'm missing the possibility that lightly weighted kickwax works like a glide wax. ? Seems unlikely. Another angle is that a ski track isn't like a floor. ...Then again many ski tracks are firm like a floor. Given the irregularites of a track it almost seems like a kickzone should be higher off the ground, yet still collapse easily with the amount of pressure a kick generates. Maybe a kick doesn't generate more than bodyweight? Maybe kickwax doesn't cause friction when it's moving/gliding and only works when it STOPS. Unlikely. Kickwax causes lots of friction. But maybe if kicking isn't more than bodyweight then we just have to put up with this friction? Anyway, if there's a difference between the weighting of a ski when we glide on it while diagonal striding and when we kick on it then the ski-makers should isolate that difference and build their kickzone around that. ...So it offhand seems to me. --JP |
#5
|
|||
|
|||
Usual wax pocket theory seems wrong...
On Mar 26, 1:47*pm, John Forrest Tomlinson
wrote: Jeff, How many pairs of skis do you have? *It seems you're constantly having problems with your skis. This is a camber theory question---mostly questioning the value of half-weight camber. I also recently had a nowax theory question. I've only had a complaint about my touring waxable skis --- my fave local pro shop only got that ONE pair in all year so I wasn't in a great position to be picky --- also I didn't know as much then about touring skis as I do now. Before my great old tour skis broke I had no complaints there. (I would've been be VERY impressed if the shop that carried the Fischer tour skis that I recently got had said, "Whoa, don't get these, they have soft tails that'll crash ya and they're heavy-feeling so get "X" instead or search eBay for some great old ones." Do shops even do flex testing for same-size tour skis or know what the optimal flexes are for touring? Maybe a good shop would've recognized and thrown out the ones I got...) I do have a pair of extremely light and quite soft 1992 Rossi's top race skis in skate and classic that serve me well in races. I don't think I've complained lately about race ski theory. Yeah, I wish I had a ski budget and a shop that had a wide range of flexes in a wide range of skis that I use so that I could get a good fit on every pair, but... I still would likely end up with ski theory questions! --JP |
#6
|
|||
|
|||
Usual wax pocket theory seems wrong...
On Thu, 26 Mar 2009 13:41:01 -0700 (PDT), jeff potter
wrote: Yeah, I wish I had a ski budget and a shop that had a wide range of flexes in a wide range of skis that I use so that I could get a good fit on every pair, but... I was only suggesting that because I have the impression you keep getting skis that don't work right, which is a false economy even if they're cheap. If you get skis that work just right, perhaps that'll make it worth spending a lot on those one or two pairs. |
#7
|
|||
|
|||
Usual wax pocket theory seems wrong...
On Mar 26, 8:38*am, jeff potter wrote:
It seems to me that the best wax pocket would be one where the kick wax is off the snow when ALL your weight is on one ski --- that's the condition in which MOST gliding occurs. Another angle is that a ski track isn't like a floor. ...Then again many ski tracks are firm like a floor. Given the irregularites of a track it almost seems like a kickzone should be higher off the ground, yet still collapse easily with the amount of pressure a kick generates. --JP Both Zack Caldwell and Mark Waecher load both the 8 cm and 15 cm back points with the 15 cm back point simulating full weight loading. Zack notes that at full weight 15 cm back, he checks to see if the grip wax pocket forward is still open. My Atomic's pretty much work the way Zack says. My cold Atomics are easy closing skis (55% of body weight to 0.2mm and an additional 2 kg to close). I found that I pretty much lost all of my grip wax back of the balance point after a classic marathon even using green klister as a base binder. Even with the easy closing, the glide well. The down side is wax loss after 30+ km. Edgar |
#8
|
|||
|
|||
Usual wax pocket theory seems wrong...
On Mar 26, 11:38*am, jeff potter wrote:
The usual way of approximately locating the wax pocket of a classical ski is to stand on both skis, equally, and slide a paper under them. Where the paper binds is the outer limits of the pocket. Official doctrine says the wax pocket keeps the kick wax off the snow when gliding or doublepoling. No, it doesn't! It only works for 2-footed gliding and part of doublepoling. It seems to me that the best wax pocket would be one where the kick wax is off the snow when ALL your weight is on one ski --- that's the condition in which MOST gliding occurs. It then seems that the camber should be designed to collapse only when one kicks or steps off of the ski, putting MORE than 100% of body weight onto the ski. With the way my skis are now when I glide while diagonal striding I'm contacting the snow and causing friction with about 50% of my kickwax zone. Only when we use the klister zone is all the kickwax off the snow during the diagonal stride glide. I'm thinking that all classic skis should have wax pockets that function like a klister zone. Klister skis should just have higher pockets because klister is thicker. So, what am I missing? I suppose I'm missing the possibility that lightly weighted kickwax works like a glide wax. ? *Seems unlikely. Another angle is that a ski track isn't like a floor. ...Then again many ski tracks are firm like a floor. Given the irregularites of a track it almost seems like a kickzone should be higher off the ground, yet still collapse easily with the amount of pressure a kick generates. Maybe a kick doesn't generate more than bodyweight? Maybe kickwax doesn't cause friction when it's moving/gliding and only works when it STOPS. Unlikely. Kickwax causes lots of friction. But maybe if kicking isn't more than bodyweight then we just have to put up with this friction? Anyway, if there's a difference between the weighting of a ski when we glide on it while diagonal striding and when we kick on it then the ski-makers should isolate that difference and build their kickzone around that. ...So it offhand seems to me. --JP Jeff: Another way to determine your kick wax pocket is to wax a little longer than you think the pocket is with a soft wax, and then go ski, especially in abrasive conditions. If you ski long enough, you will be able to see and feel with your hand where the wax has worn away to. What's left is your wax pocket, at least for those conditions. I think the Fischer race ski "912" construction (or something like that) is supposed to not contact the snow until you really kick it down, addressing your concern. In the early days of composite race skis, it was harder to kick down and "set" the wax. The american team used to boast that Bill Koch could kick down with some multiple of his body weight, which I can't recall. Kniessel or Peltonon had a ski with a knob just in front of the binding that you could turn to adjust the stiffness of the wax pocket, using a Kevlar strap inside the ski. Bert Kleerup had a pair in his shop, and said some Russian used that model in competition. You would soften them up for the climbs and harden them up for the descents and flats, I guess. Randy Bladel |
#9
|
|||
|
|||
Usual wax pocket theory seems wrong...
On Mar 26, 11:38*am, jeff potter wrote:
The usual way of approximately locating the wax pocket of a classical ski is to stand on both skis, equally, and slide a paper under them. Where the paper binds is the outer limits of the pocket. Official doctrine says the wax pocket keeps the kick wax off the snow when gliding or doublepoling. No, it doesn't! It only works for 2-footed gliding and part of doublepoling. It seems to me that the best wax pocket would be one where the kick wax is off the snow when ALL your weight is on one ski --- that's the condition in which MOST gliding occurs. It then seems that the camber should be designed to collapse only when one kicks or steps off of the ski, putting MORE than 100% of body weight onto the ski. With the way my skis are now when I glide while diagonal striding I'm contacting the snow and causing friction with about 50% of my kickwax zone. Only when we use the klister zone is all the kickwax off the snow during the diagonal stride glide. I'm thinking that all classic skis should have wax pockets that function like a klister zone. Klister skis should just have higher pockets because klister is thicker. So, what am I missing? I suppose I'm missing the possibility that lightly weighted kickwax works like a glide wax. ? *Seems unlikely. Another angle is that a ski track isn't like a floor. ...Then again many ski tracks are firm like a floor. Given the irregularites of a track it almost seems like a kickzone should be higher off the ground, yet still collapse easily with the amount of pressure a kick generates. Maybe a kick doesn't generate more than bodyweight? Maybe kickwax doesn't cause friction when it's moving/gliding and only works when it STOPS. Unlikely. Kickwax causes lots of friction. But maybe if kicking isn't more than bodyweight then we just have to put up with this friction? Anyway, if there's a difference between the weighting of a ski when we glide on it while diagonal striding and when we kick on it then the ski-makers should isolate that difference and build their kickzone around that. ...So it offhand seems to me. --JP Hi again, Jeff: Remember also, that in diagonal stride or kick-double pole, that a good portion of your weight is taken off of your single gliding ski by your arm and pole (for diagonal) or both arms and poles (kick-double pole). Also, the weighting of the ski is a dynamic thing, not just an unchanging force in the middle of the ski. A good skier is "unweighting", maybe subtley, while gliding on that single ski as a preparation for "weighting" when they kick, and therefore keeping the wax off of the snow while gliding. Thirdly, many racers rarely put kick wax as far back as the heel, and then glide with their weight on the heel as much as possible. Randy |
#10
|
|||
|
|||
Usual wax pocket theory seems wrong...
On Mar 26, 4:50*pm, wrote:
On Mar 26, 8:38*am, jeff potter wrote: Another angle is that a ski track isn't like a floor. ...Then again many ski tracks are firm like a floor. Given the irregularites of a track it almost seems like a kickzone should be higher off the ground, yet still collapse easily with the amount of pressure a kick generates. --JP I should add that the flex/camber testing that Zack and Mark do are only as good as their skill at interpreting the results., As Jeff notes, a ski track isn't a floor. The good ski pickers need to base thier picks on their experience as to how skis measured as they measure them would be expected to act on the different snow conditions. That is, any flex/camber bench test is only a proxy as to how the skis behave on hard snow, soft snow, etc. So, that said, all the theory and testing is only as good as to how the data is interpreted. Edgar |
Thread Tools | |
Display Modes | |
|
|
Similar Threads | ||||
Thread | Thread Starter | Forum | Replies | Last Post |
LEVEL III THEORY TECHNICAL NCCP | Adam Gale | Nordic Skiing | 0 | November 7th 05 02:41 AM |
Which pocket for camcorder? | Iain D | Snowboarding | 4 | February 6th 04 05:34 PM |
On finding your wax pocket | Anders Lustig | Nordic Skiing | 0 | January 30th 04 12:36 PM |
technique is wrong or ski size is wrong: could you please help? | S. S. | Nordic Skiing | 3 | January 20th 04 10:02 AM |
Hill climbing techniques for skating (was Wisconsin theory) | Ken Roberts | Nordic Skiing | 0 | July 10th 03 01:00 PM |