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How long is long, a numbers game

post #1 of 24
Thread Starter 
The K2 Coomba and Fischer Watea 101 have a lot in common;

Sidecut: Coomba 135 -102-121mm, Watea 134-101-124mm
Turn radius: 22 @174cm, Watea 25 @ 192cm
Flex soft for both

Running length: 174cm Coomba has a 152.5cm Running length, the 192cm Watea has a 160cm running length.

the 192cm has only a 7.5cm longer running length than the 174cm.
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post #2 of 24
Thread Starter 

Where did the 10.5cm go?

Look at the tip;
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post #3 of 24
the white paper is confusing. is the inside or the outside edge showing the contact point for the running surface?

Usually the paper's inside edge would mark the running surface, but there is no way that's the case in those photos.
post #4 of 24
Thread Starter 
and the tail;
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post #5 of 24
Thread Starter 
Quote:
Originally Posted by samurai View Post
the white paper is confusing. is the inside or the outside edge showing the contact point for the running surface?

Usually the paper's inside edge would mark the running surface, but there is no way that's the case in those photos.
The paper was gently slid under the ski until it met resistance. The first photo set is with the boots aligned.

The tip and tail photo sets are with the running surface termination points aligned.

Michael
post #6 of 24
interesting barrettscv....
how is your son enjoying the coomba?

i must say, your image is something i might do, especially since i'm interested in the watea 101 as the 94 in the 178 has become my favorite ski of all time... but, the 192 seems too long. i keep thinking i'd want it in like a 185, but your image makes me think again.

is it true that your white paper shows the contact point? meaning the watea has quite a bit of early rise (looks like a couple inches earlier rise then the coomba, which is supposed to have early rise.)

I hope the skis are treating you well.


cheers,
holiday
post #7 of 24
Thread Starter 
Quote:
Originally Posted by Holiday View Post
interesting barrettscv....
how is your son enjoying the coomba?

i must say, your image is something i might do, especially since i'm interested in the watea 101 as the 94 in the 178 has become my favorite ski of all time... but, the 192 seems too long. i keep thinking i'd want it in like a 185, but your image makes me think again.

is it true that your white paper shows the contact point? meaning the watea has quite a bit of early rise (looks like a couple inches earlier rise then the coomba, which is supposed to have early rise.)

I hope the skis are treating you well.

cheers,
holiday
My son has yet to use the Coomba, but I'm sure he will like 'em.

I need to take a side profile of the tips & tails. The Watea tips are tobagoon like with a tall and round profile. The K2 is water ski like, not as tall but with a profile like a french curve.

Does that answer the question?

Michael
post #8 of 24
Thread Starter 
I need to mention that K2 has its own length determination that understates size.

Michael
post #9 of 24
There is a lot more early-rise in both those skis than I had assumed.
post #10 of 24
Thread Starter 
Yes, I'll take a few more pixs and try to offer more detail.
post #11 of 24
Just throwing this out there...could be wrong....

Could it be possible that both of these skis were designed to run with skiers on them and in softer snow? In that case, wouldn't there be more contact length between ski and snow?
post #12 of 24
Thread Starter 
I think you have a strong point.

The ski will be de-cambered while in deep snow. I noticed the tips curling back and staying above the snow while skiing. It becomes a reverse camber ski, essentially.

This does extend the contact length as you suggest.

Michael
post #13 of 24

Where the heck is the middle of my ski???

The Watea 101 is not sold as a twin tip, but in fact the tails (with the plastic cutout extension) rise exactly the same height as the tips, taking about 2" off the running length at the back end. For me the question really isn't the running length, but what effect does the non-contact part of the ski have on the soft snow skiing experience?

If you have true twin tips and never ski backwards, does the back tip give you any benefit, or is it just a hinderance? Can I just subtract the twin tip from my calculation of how the ski will feel lenghwise? The other issue is binding mounting position. How do you measure the middle or mount postion? Is it from the flat, partially turned up, twin tip tail, or the end of the running surface? Same goes for low profile tips. Even the manufaturers are making mistakes and now cover their butts by putting multiple mounting lines on the skis. How many threads have we seen in the last few years about plus or minus mounting postion?

It seems like in today's market ski length is mostly voodoo. A whole lot of people are on skis that have an effective length that is 10+ cm shorter than the advertised length. As always the bottom line is how do they ski, but that is getting harder and harder to figure out without demoing. The good news is that the confusion is actually making people aware of issues like mounting position, which most never paid attention to in years past.
post #14 of 24
Thread Starter 
Quote:
Originally Posted by mudfoot View Post
The Watea 101 is not sold as a twin tip, but in fact the tails (with the plastic cutout extension) rise exactly the same height as the tips, taking about 2" off the running length at the back end. For me the question really isn't the running length, but what effect does the non-contact part of the ski have on the soft snow skiing experience?

If you have true twin tips and never ski backwards, does the back tip give you any benefit, or is it just a hinderance? Can I just subtract the twin tip from my calculation of how the ski will feel lenghwise? The other issue is binding mounting position. How do you measure the middle or mount postion? Is it from the flat, partially turned up, twin tip tail, or the end of the running surface? Same goes for low profile tips. Even the manufaturers are making mistakes and now cover their butts by putting multiple mounting lines on the skis. How many threads have we seen in the last few years about plus or minus mounting postion?

It seems like in today's market ski length is mostly voodoo. A whole lot of people are on skis that have an effective length that is 10+ cm shorter than the advertised length. As always the bottom line is how do they ski, but that is getting harder and harder to figure out without demoing. The good news is that the confusion is actually making people aware of issues like mounting position, which most never paid attention to in years past.
Could not agree more. I'll try to answer a few...

...what effect does the non-contact part of the ski have on the soft snow skiing experience?

The turned up tail helps when the ski is pushed sideways in deep snow, it would help the skier hockey-stop in crud. The turned up tail hurts hardsnow carving IMO since the tail cannot retain contact with the firm surface. The tail can help when backing up in tight trees or rocks. Overall, I'll take a flat but round shaped tail like the Coomba.

Can I just subtract the twin tip from my calculation of how the ski will feel lenghwise?

Suggested, I would subtract 10mm from the length of the 101 when compairing to another ski with a flat tail.

The other issue is binding mounting position. How do you measure the middle or mount postion?

One of the reason I put Railflex on the 101 is to play with the binding location. The factory position is very good for deep snow. I'll try going forward If I have a hard snow day.

Cheers,

Michael
post #15 of 24
Thread Starter 
Another compairo... The RX8 pictured below is a 175cm size.

It's running length is 7cm less than the 192cm 101.

And the RX8 has a turned up tail also.
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post #16 of 24
I really hate to interrupt(not really), but this thread resembles the "Ways skiing is like sex" thread........
Quote:

How long is too long?
Where did the 10.5 cm go?
Look at the Tip, and the tail

.............. i must say, your image is something..........
........the watea has quite a bit of early rise ..............

I need to take a side profile of the tips & tails.
post #17 of 24
Quote:
Originally Posted by barrettscv View Post
Another compairo... The RX8 pictured below is a 175cm size.

It's running length is 7cm less than the 192cm 101.

And the RX8 has a turned up tail also.
This is very close to turning into a Palmer P02 thread.

Would you consider a bit of experimentation?

Magic marker the base and side edges from the contact point up to the tip.

Leave a film of wax on the magic markered edges.

Go ski some hard and semihard-pack.

Then look for magic marker signs, on the base edge and on the side edge.

Looking for:
side edge mark ruboff distance upwards from contact point
difference between base edge mark and side edge mark ruboff distance from contact point.
post #18 of 24
The distance between contact points only applies to skiing on flat surfaces. If you are in the snow, its not that relevant.
post #19 of 24
t, you'll notice that,

in spite of using 'contact point' in my above post when I meant 'measured base contact point',

I do not assume that the base contact point is also the edge contact point.
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post #20 of 24
Very good points tr and comprex.

The tail geometry can also have a big effect on how the float of the ski tapers off in deep snow. A very abrupt tail can make the back of the ski kind of hooky, whereas turned up and shaped tails will feather the load smoothly. It's just a more gradual way of going from full load to nothing at the back end of the ski. The various fish-tail, swallow tail, and scarfed-tail skis are shaped for this reason. I'm sure it's a voo-doo art.
post #21 of 24
comprex,

I thought the definition of contact points was the points where the tips and tails of the ski lose contact when two skis are held base to base. I think we are agreeing in principal but equivocating on that term.
post #22 of 24
I reckon you're right on that there, tromano.

My reason for being a curmudgeonly stickler is that it's not intuitively obvious at all for the edge to be able to engage snow beyond the flat-base contact point.

So we need to define an 'edge contact point length'. I think the concept is -quite- meaningful for hardpack skiing as it defines the starting and end points of a carve.

Case in point (sorry): look at the RX8 pictured above. How often is that RX8 not on edge? That's a 6 cm offset there. 9cm or so for the Watea. Which "running length" is meaningful? If one correlates time-of-nonzero-tipping angle to overall skill, we might make a prediction that a beginner will find the RX8 "squirrely" and a higher level skier "rock stable"?
post #23 of 24
This thread should help make it more obvious just how painfully short a lot of men in the east are skiing their fatter skis.

comprex- if you are skiing on hardpack, will the edge contact "point" (loosely defined) be the widest point of the ski? I know on many of my hard snow skis this would describe a length a good bit longer than the running length described here. This sort of sidecut design has been popular since 1999 or so, no?

On hard snow it seems that a 165 SL ski "skis longer" than many/most 170-180 freeride skis currently on the market.

I'm going to keep my 193 Blowers for tree skiing and pick up something 200+ with a flat tail for open pistes.
post #24 of 24
My understanding is that a full twin-tip ski is simply designed to allow the skier to ski switch - nothing more. The compromise is that a twin-tip sacrifices running length, so a twin-tip skis like a much shorter ski that it is. No problem if you're just doing park and pipe, or taking off and landing switch on natural features outside the park. In addition, most twin-tip skis are lighter, softer in flex and don't have the torsional rigidity to hold an edge as well - desirable for a park ski, but not an all-mountain ski.

So, as an all-mountain ski for conditions where running length on the snow matters, the twip-tip is not as suitable as a ski with a flatter tail.

I have a pair of 190cm wizard Volkl Explosivs that have a partial twin-tip - that is, the tail is only slightly turned up and there is not much loss of running surface, so this design is a good compromise. I have had to back up on several occasions when I have been faced with unskiable terrain ahead, and this feature made it much easier.

I like to have my bindings mounted so that the ball of my foot is at the mid-point of the running surface of the ski. This position makes pivoting easier and quicker, gives me more agility in bump skiing and better feel in carving - because then there is roughly the same amount of lumber ahead of or behind the ball of my foot.

The compromise is that for high speed skiing, the optimum position would be about 1cm further back. However, its been a few years since I last did 100km/hr, so.....
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