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Sinus wave in the snow


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Originally posted by mirror70

By any chance, are you a plumber?

HaHa:rolleyes:

I thought it was due to not fully engaging the nose, hence the the oscillation: nose carving in more than the rest of the board, then straightening out when too bent, and the cycle continues.

Seems OK when I put major pressure to the front foot/nose and commit to head uphill.

Gives a pretty but not clean pattern in the snow

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You can also get it if you are leaning the nose over a different angle than the tail (torsional twist). I think this can happen quite easily at lower angles (such as on a Swoard) if you are highly rotating your heelside, especially with bent knees - you end up pushing your back toe down and pushing your front heel down, thus leaning the nose over more than the tail.

Phil had a really great post here a while back.

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EUREKA!!! Thanks Ken! I think that's what I've been doing! It make SO much sense...

When I adjust my stance to be a bit more higher angled the problem lessens. That's why the problem only shows up on my hard boots and with my Malamutes and it didn't show up when I was riding my clickers. Gee wish I read this about a month ago so I can try it out. My last day out will be tomorrow and I'll definitely work it out then. Thanks again for the comment and the link to the post.

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The sinusoidal wave thing used to happen to me all the time - I had too much weight on the backfoot. The main part of the board would try to carve a tigher carve with the backend of the board, but without enough pressure on the front, the nose would unflex and bounce in the carve. I've since gotten much better at keeping my weight more balances/forward biased (thanks Sean Cassidy and Snowperformace) and that has completely gone away now.

I also switch from a soft Burton UP162 with a 19cm waist to Madd170 which probably helped a bit too ^_^

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Lonerider,

I've heard this before but the funny thing is that the front end wave would subside when I shifted my weight rearward. It also subsided when I shifted my binding stance forward and narrowed it up a bit, but when I made the stance "too narrow" then it would come back. Another way I have of making the wave less pronounced would be to get really low in my stance and trying to keep my legs as soft as possible but I think this just has the affect of minimizing the effect of the wave on my body and not really making it go away. I just thought of the possibility that this "soft leg" approach would also help minimize the torque applied to the board, hmmm. I have a feeling it's a rather complicated equation involving the aforementioned weight shift but also the torque put upon the board, sidecut, board length, stance width, stance setback, etc. But I am excited about trying to minimize the torque effect on the board by upping my stance angles a bit.

Re: your equipment change I think since the MADD probably is alot more torsionally stiff than the UP that helped alot in allowing the front and back end track in the same line.

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Originally posted by astrokel

Lonerider,

I've heard this before but the funny thing is that the front end wave would subside when I shifted my weight rearward. It also subsided when I shifted my binding stance forward and narrowed it up a bit, but when I made the stance "too narrow" then it would come back. Another way I have of making the wave less pronounced would be to get really low in my stance and trying to keep my legs as soft as possible but I think this just has the affect of minimizing the effect of the wave on my body and not really making it go away. I just thought of the possibility that this "soft leg" approach would also help minimize the torque applied to the board, hmmm. I have a feeling it's a rather complicated equation involving the aforementioned weight shift but also the torque put upon the board, sidecut, board length, stance width, stance setback, etc. But I am excited about trying to minimize the torque effect on the board by upping my stance angles a bit.

Re: your equipment change I think since the MADD probably is alot more torsionally stiff than the UP that helped alot in allowing the front and back end track in the same line.

Yea, I agree that the torsional stiffness of the Madd probably helped a lot. For me, the big change was that I had TD1 before and the 3* plates gave me a lot of inward cant and unnaturally pushed me away from the nose of the board and pushed me knees together. When I rotated them to match my angles it was easier for me to put weight on my front foot *consistently* - that is what I meant. I was trying to be aggressive and drive into the turn and overflexing the nose of the board and when it sprang back at me I didn't have enough pressure on it to "keep it down" proper was that I was getting something akin to "speed wobbles" where I would swing my weight forward, not be able to keep consistent pressure, unweight the nose, have it bounce up and then would end up swing my weight forward again as the nose came back down... repeating the "wave."

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Well I tried upping the stance angles (from 40r-53r to 47r-60) and it did help with the wobble/wave but I still felt kinda uncomfortable with the heel side. I probably should have shifted the stance position a bit rearward (from centered on the sidecut to centered on the inserts on the Incline). I worked that stance for a half day then went back to my old stance and used the technique of pushing the knee in towards the turn to keep the board edge straight and minimize the torque which really helped but stiil was problematic on the steeps. I think the thing I REALLY need to do is to just go ahead and get a board with a bigger scr than the incline for the steeps and narower in order to get my toe and heel over the edges for better control. So I guess THAT is what I'll be doing during the off season, figuring out the right board to get for next year!:) It just feels like I've pushed the board as far as I could get away with with as much technique as I could muster so the next step is working out the right equipment. Oh well it'll all have to wait til next season... :(

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I'm not a technique expert by any means but I do have a comment to offer. True experts - please comment and correct as necessary :)

Would you be willing to try a more parallel stance on your Incline when you're riding it with hard boots? 13* of splay is quite a bit for hard boots and it seems to me that it might encourage you to twist the board a bit even when you're not trying. It also might make it harder to apply even pressure to the board through both legs when you angulate your joints.

I used to think I needed a 5* splay in order to be comfortable; that perception was induced by some flaws in my riding that I have since improved upon if not corrected. I now use about 2* of splay, and might try parallel angles next time I go out so see if I can be comfy on it.

Also, I think the Incline's inserts are in fact centered about the sidecut. The board is tapered, so it might appear that the inserts are set back a bit - they are if you consider the overall length - but Sean from Donek stated, I think over on rec.skiing.snowboard, that the inserts are centered about the sidecut.

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Mike, I'll put on this down in my notebook for trying out next year. Thanks for the relay on your experience. My natural foot position is kind of splayed and the stance angles kind of reflect my natural splay but I can see what you're talking about regarding the different inputs when the angles are different. Bummer that I'm just sorta getting into that place, where I think I'm just about getting an understanding of all the different inputs, at the end of the season but I guess that's why this whole thing just keeps on being interesting:) .

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Hi Jim,

I think so too. I solved the problem since by tucking in my rear knee on backside and pressuring the nose more evently and for longer. I still see it occasionally on very hard pack where subttle pressure difference shows more (mainly because I am more cautious and less aggressively attacking the turn).

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