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All Mountain Twin-tip Shootout: PE vs. Karma

post #1 of 44
Thread Starter 
Almost every time someone asks for recommendations on all-mountain twin tips here, the K2 Public Enemy and Volkl Karma float to the top of the list. Since I own and ski both of these twins, I figured it would be good to do a head to head review.

About me:
- Age 37
- Level 8-9 skier (most of the time!)
- Height: 6'1" Weight: 185lb
- Ski 150-180 hours and about 1 million vertical ft per year (20-25 days)
- 28.0 Salomon Xwave 9 boots, 325mm sole length

The skis:
- 185cm Volkl Karma with Tyrolia RailFlex LD 12 bindings positioned 1.5cm forward of the "FR" mark
- 179cm K2 Public Enemy with Salomon Z12 Ti bindings mounted 2.5cm forward of mid-sole mark

Snow Conditions Included:
- Groomed packed powder
- Untracked powder 12-16"
- Cut powder and crud
- Corn snow
- Loose and frozen granular
- Spring slush

--

To the eye, the PE and Karma appear well matched in the sizes reviewed. The 179cm PE has an overall length of 178.6cm and tip/waist/tail dimensions of 118/85/109mm. The 185cm Karma checks in at 180.5cm long and 119/87/111mm. Despite being less than 2cm shorter than the Karma, the PE's chord length (running length) is almost 11cm shorter. And herein lies a defining difference between the two skis; while the Karma tips and tails are comparable to tip shapes on most all-mountain skis, the PE's tips and tails are longer and shallower as shown below:


Image: PE tip in foreground, Karma tip in background. Skis are aligned at their forward contact point.


Image: PE and Karma tip, chord, and tail dimensions compared. Skis aligned at chord center.

The effect of tip geometry is fairly dramatic; while the Karma sizes out like a 175cm traditional ski in terms of the running length, the PE is comparable to a 165cm traditional ski. The end result is that the PE has a significantly smaller turning radius than the Karma (18.2m versus 21.5m, calculated from sidecut and actual chord length) and feels a lot more maneuverable on hardpack. In tight spaces or cut up snow, this size difference fades away a small bit as the skier still has to contend with the tips and tails on the PE, but it's a minor issue. In powder, however, the difference all but disappears as the PE's long shallow tips and tails provide usable surface area and float. And this gives the PE a dual personality; it skis shorter and is more fun and maneuverable than the Karma on hardpack, but skis long in powder and soft snow when the tips and tails come into play.

In powder, I find both skis to be great. Both skis will float and ride on top of the snow with enough speed, but the PEs seem to ride up a bit easier. In spring snow, both skis are very good, but the PE seems to surf over the heavier slush more easily. In both cases, I believe the PE's tip geometry is the reason.

I do not think either ski is really strong in crud (say compared to an all-mountain bulldozer like the Elan M666 or M777) and they have different behavior here. The Karma will start to slice or plow through crud like a traditional ski, but not have enough grunt to really pull it off as well. The PE is more likely to ride *over* the crud because of those tips. While not as confident feeling as a true crudbuster, riding the PEs up over crud turns out to be fun and a fairly effective way to handle crud if you can hang on for the ride. Both skis are wide enough that they can deal with cut up snow pretty well.

On hardback, both skis are surprisingly good. I am able to rail hard carves on both skis, and sometimes feel these skis are as good as traditional all-mountain skis in this regard. Except they are slower edge to edge than many all mountain skis due to largish turning radiuses and wide waists. The combination of the smaller turn radius and slightly narrower waist does make the PE about 15% faster edge to edge than the Karma for a 20m/s (45mph) speed -- the shorter chord helps a lot here. Both skis are fairly energetic, but the PE clearly has more energy and spunk than the Karma, especially in the tail. Every once and a while I will get in the backseat at the end of a turn, and the PE let's me know it with a fun kick. The Karma is rather stiff all the way through, and I do not feel it has as much character as the PE.

In moguls, I find the Karma to be much too stiff and plank-like. Now, keep in mind that I am not a great mogul skier, but I have run across skis that make it easier for me, and the Karma is not one of them. The PE is notably better in bumps, where it turns quicker, spins easier, and seems to flex a whole lot better. Almost makes me feel like I am skiing the bumps half decent! Both skis suffer from their width in bumps, which makes them less nimble feeling than narrower skis I have sampled.

Overall, I think the PE is a better east coast twin tip because the dual personality of the tip/tail geometry makes it strong on hardpack and soft snow. This was never more apparent to me than when skiing some spring conditions today. Through most of the day, the snow was soft and the PE was surfing/riding over it quite effectively. Towards the end of the day, the snow firmed back up and even got icy in spots, and the PE was carving quite well. Most late-day runs were a combination of soft and firming snow, and the PE handled the variable conditions with aplomb. When I did 5-6 bump runs earlier in the day, I found the PEs to be excellent in the "kiddie" line I took down the side of the trail where the bumps were smaller and easier to ski.

Note that binding position has an important effect on the behavior of these skis. I position my bindings with the BOF method, which generally puts my boot midsole 6-7cm behind the ski's chord center. This tends to enhance overall feel and performance but often makes the skis less apt to ride high in powder. The PE's longer tips alleviate this somewhat, by adding more float up front as the tips come alive in powder. It's kind of like having an on-demand longer ski when needed, and works well with BOF mounting.
post #2 of 44

Have you used the binding to alter the performance of the ski?

Hi skier219,

Very nice review! It’s a deep analysis and well written; thanks for posting. Since you’re using the Railflex binding have you tried moving the binding throughout a day of skiing? If you have what was your experience?

Thanks again,

Michael
post #3 of 44
Nice reviews. Have the older PE's (80cm under foot) and mounted only 1 cm forward. In your opinion, how till this change the character of the ski from the 2.5 cm position?
post #4 of 44
Good review and certainly well written. I may disagree with some aspects but reviewing skis is not a science.
post #5 of 44
Great review; nice that someone is looking at the (vast) diffs in twin tip design. I have Priors with the PE style - long, slowly curving tip - and it handles like a fatter version of how you describe the PE - skis short on groomers, "finds" the extra length in pow and crud, tends to float sooner than expected so can get jouncy in hard crud. Prior says this design also reduces the need to backseat in serious pow, although I've only had my Priors in calf-high, so can't say.
post #6 of 44
Great analysis. I do have a question relating to the surface contact aspect. How does this differ from non-twin tipped skis when measuring from the tip? All tips are turned up so how is this different? I understand the tail issue.
post #7 of 44
Thread Starter 
Quote:
Originally Posted by michaelsnead View Post
Hi skier219,

Very nice review! It’s a deep analysis and well written; thanks for posting. Since you’re using the Railflex binding have you tried moving the binding throughout a day of skiing? If you have what was your experience?

Thanks again,
Michael
Michael,

I have moved the bindings around some on the Karmas, and it has a notable effect. I feel like the Karmas ski better on groomed/hard snow when I go +1.5 (which gets me about 1cm behind my BOF point). At the center point (which puts me on Volkl's FR mark) the tips don't get enough pressure on groomed in my opinion, but the skis float over crud and through powder better. I have not gone to -1.5, since I haven't seen the need (maybe in super deep powder on steep trails).

If I was to mount the RF plate again, I would probably set it up so that the rear point was on the "FR" mark, and then +1.5 would be close to my BOF point, with the center point in the middle. I think this would cover the full range of bindings positions I would need for the kinds of conditions I encounter on these skis.

Craig
post #8 of 44
Thread Starter 
Quote:
Originally Posted by bumpdad View Post
Nice reviews. Have the older PE's (80cm under foot) and mounted only 1 cm forward. In your opinion, how till this change the character of the ski from the 2.5 cm position?
It really depends on your boot sole length, or more directly, where the ball of your foot (BOF) lies in relation to the ski's center mark. If you have a larger foot than me (my boots have 325mm sole length) then +1cm may put you in the same sweet spot I find at +2.5cm. If you have smaller feet, your BOF is likely behind the chord center a bit, so you would probably get better powder performance but less efficient/direct turns on hardpack than I get.

K2 does have some guidelines on positioning for the PE, and they say 0 to 2cm forward is a good place for all-mountain use. But without knowing the specific boot sole length or how the foot is positioned in the boot, that is really a very general guideline. I do think it makes sense to come forward a certain amount for everyone on this ski (short of dedicated powder-hounds).

If you know your boot sole length, and where your BOF lies in relation to the midsole mark, we can figure out what the +1cm mount really means to you and how it would compare to me.

Craig
post #9 of 44
Thread Starter 
Quote:
Originally Posted by beyond View Post
Great review; nice that someone is looking at the (vast) diffs in twin tip design. I have Priors with the PE style - long, slowly curving tip - and it handles like a fatter version of how you describe the PE - skis short on groomers, "finds" the extra length in pow and crud, tends to float sooner than expected so can get jouncy in hard crud. Prior says this design also reduces the need to backseat in serious pow, although I've only had my Priors in calf-high, so can't say.
Interesting to hear -- your description sounds exactly like what I experience with the PE, so I wasn't imagining it after all .

I skied some awesome powder last week, 8-16" deep depending on the time of day and trail, and found the PE was fairly neutral in powder when I was skiing my normal powder style turns. However, I discovered that it would float on top of the snow and ride big fun arcs if the trail was steep enough and I got going fast enough. This took a little bit of backseat pressure, but not a lot. However, the float/ride party would end pretty quick if I went even the slightest bit forward of neutral -- the tips would slowly dive and I was back to powder turns. I have a feeling a mount point farther back would have improved the behavior.

Craig
post #10 of 44
Thread Starter 
Quote:
Originally Posted by Finndog View Post
Great analysis. I do have a question relating to the surface contact aspect. How does this differ from non-twin tipped skis when measuring from the tip? All tips are turned up so how is this different? I understand the tail issue.
It really varies from ski to ski, but I found most of my regular (non-twin) all mountain skis have tips that are about 10-12cm long, maybe 12-14cm in some case (these are skis in the 176-185cm range by the way). The two twins here had tip lengths of 15.5-19.5cm. If all else were assumed equal, these twins effectively move the forward contact point aft, lengthening the tip and shortening the running length of the ski.

If you look at the photo, it shows how much shorter and abrupt the Karma tip is compared to the PE tip. A typical all-mountain ski would probably have a slightly shorter and more abrupt tip than the Karma.

Craig
post #11 of 44
Thanks, that helps, so it will really vary from one twin tip to another? Some may end up being several mm shorter, others just a few then.
post #12 of 44
I still dont why you mounted both skis forward. My 179cm PEs are mounted at the Freeride center.

I too was surprised how good the realitivty skinny PE is at skiing powder too.

and you finding on the PEs length explain why is great nimble groomer ski but destroys soft crud and tracked up powder. I can really lean into the front of my boot all the time cause of being mounted back.
post #13 of 44
Thread Starter 
The midsole mark on any ski is somewhat of an average location, and it is not the right mount point for every skier (in fact, it would really only be the right location if you match the average profile that went into establishing that mark). That is because we generally don't turn skis about our midsoles, we turn about the balls of our feet when we're in the front seat (ideally). Using the BOF method (advocated by Noodler and others here -- so I will defer to their previous knowledge base) I try to get exactly in the right spot where my BOF lines up with the ski's chord center, and that happened to be +2.5cm on the PEs. Actually, I stay about 0.5cm back of the BOF myself based on my positioning experiments with the RailFlex and other skis with adjustable bindings. My Elans are factory mounted on "the mark" but that ends up being only about 0.5cm back of BOF and I like their feel a lot. Most other ski brands have me 3-5cm farther back than the Elans and my self-determined sweet spot. Same would have been true of the PE's midsole mark, to the tune of 2.5cm.

I have seen some skis that have a whole set of midsole marks labeled by boot sole length, which gets you closer to the ideal BOF location, but that still has an assumption built in -- namely, where the BOF falls in relation to the midsole.

If you search on "BOF" you'll see some of the posts from Noodler and others that can probably explain the concept better than me.

Craig
post #14 of 44
I checked a bunch of the twintips around my house after getting some PEs and finding what skier219 found. Initially, I couldn't find any twins with a similar running surface then I remembered my Pocket Rockets had what I called reverse camber in their tips......when skiing on groomers you could see that a large part of the tip was not engaged with the snow. I checked them out and found they do have a significantly shorter running surface like the PEs. Sounds like K2 borrowed a trick from the Pocket Rockets when making the Public Enemies. No wonder WTFH likes them so well.
post #15 of 44
Great review, well thought out and written. And timely too, given the popularity of these two skis.

You raise a couple of interesting points that I had previously noted in a mini review of my scratch BC's. That is that a lot of these twin tips actually ski shorter in a carving context. Don't know if it is due entirely to the tip geometry or the ollieband (rocking chair?) in the tips but the 178 scratch bc's actually ski like a 20m radius 168 on hard pack due to the fact that the tips and tails do not fully engage on hard snow. While they are not as quick edge to edge due to the 99mm under foot, they other wise ski a lot shorter and carve really well. I was surprised that on some hard snow conditions they were actually gripper than my Atomic SL:11's.

My personal experience on the PE's was similar. I demoed these last year in a 179 and found them to carve like a shorter ski. They did seem a little light for me. While I really liked them at slower speeds and in the bumps, I had the feeling that I was overpowering them at higher speeds and that they were getting knocked around a bit. Just not grippy enough for me on hard snow, but then I am 6'3" and 225lbs. Which is kind of funny, because I have a pair of the first generation k2 enemys which I love and which hold up much better at speed. I am seriously thinking about a pair of the new PE's for my daughter who is still pretty tall but quite a bit lighter. I think these could be a really good ski for her.

Again this was a great technical review. Two thumbs up for 219
post #16 of 44
Great review...

Curious.....how are you measuring length? Point to point, or along the running surface?

Thanks...
post #17 of 44
Thread Starter 
Quote:
Originally Posted by Highway Star View Post
Great review...

Curious.....how are you measuring length? Point to point, or along the running surface?

Thanks...

The overall length I gave was the linear length from tip to tail, measured by projecting the tip and tail position down onto my workbench surface.

I measured running length a bunch of different ways, and they all came within about 0.5 cm of each other. I ended up putting the skis base to base, marking the forward and rear contact points, and using that to spec the running length.
post #18 of 44
Thread Starter 
Quote:
Originally Posted by viking kaj View Post
Great review, well thought out and written. And timely too, given the popularity of these two skis.

-snip-

My personal experience on the PE's was similar. I demoed these last year in a 179 and found them to carve like a shorter ski. They did seem a little light for me. While I really liked them at slower speeds and in the bumps, I had the feeling that I was overpowering them at higher speeds and that they were getting knocked around a bit. Just not grippy enough for me on hard snow, but then I am 6'3" and 225lbs. Which is kind of funny, because I have a pair of the first generation k2 enemys which I love and which hold up much better at speed. I am seriously thinking about a pair of the new PE's for my daughter who is still pretty tall but quite a bit lighter. I think these could be a really good ski for her.

Again this was a great technical review. Two thumbs up for 219
Thanks for the comments! I had an interesting ski weekend with the PEs. Saturday was frozen granular with about 3-5" of fresh snow on top (dust on crust basically) and I skied my Elan Mag 12. Sunday started on the Mags until I realized there was 8-10" of fresh powder on most trails : so I ran back in and switched out for the PEs. In the few runs I got in before the powder was tracked all to oblivion, the PEs were great. Later in the day they gave a fun bronco ride in the chopped snow and crud. Today (Mon) was groomed packed powder, which was quite hard on most trails. I would normally have skied the Mags today, but they were already packed in the car under all our crap, so I stayed on the PEs one last day. I was amazed to see how well they carved on the hard snow -- I was basically pushing them as hard and fast as I can ski, and they responded wonderfully. I was doing one steep run with a lot of large rollers and drops, and the PEs were ideal for hard carves followed by short hops and then more carves. After today, I found myself thinking that the PEs could be my only skis. I get more and more impressed with them every time I ski them.
post #19 of 44
Hey 219, what length do you think would work best for my daughter in the PE? She's 5'11" 130 lbs level 8-9 and skis everything on the hill except the park. She skis well enough that she is mostly on racing skis on hard pack (GS and SL) with one pair of fatties for pow days. The PE's would be her fourth ski. I'm thinking she will mostly use the PE's in an all mountain role with perhaps a few forays into the park with some of her pals who are jibbers.

I was thinking a either a 169 or a 174, and kind of leaning toward the 169 because of the possible park angle. Does this feel right to you?
post #20 of 44
Thread Starter 
Quote:
Originally Posted by viking kaj View Post
Hey 219, what length do you think would work best for my daughter in the PE? She's 5'11" 130 lbs level 8-9 and skis everything on the hill except the park. She skis well enough that she is mostly on racing skis on hard pack (GS and SL) with one pair of fatties for pow days. The PE's would be her fourth ski. I'm thinking she will mostly use the PE's in an all mountain role with perhaps a few forays into the park with some of her pals who are jibbers.

I was thinking a either a 169 or a 174, and kind of leaning toward the 169 because of the possible park angle. Does this feel right to you?

I think 169cm would be better considering she is only 130lbs (if only considering height, 174cm would be ideal for big-mountain use). But I am curious -- what are her other skis and what are the lengths? We can use that as guidance to figure out which PE would be right.
post #21 of 44
Quote:
Originally Posted by skier219 View Post
I think 169cm would be better considering she is only 130lbs (if only considering height, 174cm would be ideal for big-mountain use). But I am curious -- what are her other skis and what are the lengths? We can use that as guidance to figure out which PE would be right.
Rossi World Cup 9s 155

Dynastar Course Comp 66 176

Dynstar Little Big Fat 169

I'm leaning towards the 169 because if your analysis is right the PE in this length should ski like a 159 with a 14.5 meter radius on hard snow, should give her plenty of float in powder, and will be easier to get around on in the park than the 174.
post #22 of 44
Quote:
Originally Posted by viking kaj View Post
Hey 219, what length do you think would work best for my daughter in the PE? She's 5'11" 130 lbs level 8-9 and skis everything on the hill except the park. She skis well enough that she is mostly on racing skis on hard pack (GS and SL) with one pair of fatties for pow days. The PE's would be her fourth ski. I'm thinking she will mostly use the PE's in an all mountain role with perhaps a few forays into the park with some of her pals who are jibbers.

I was thinking a either a 169 or a 174, and kind of leaning toward the 169 because of the possible park angle. Does this feel right to you?
out west 174.... east thats a gray area and I skied the 174 and it felt less nimble than my 179s because I didnt have enough edge to do quick poppy turns.

Longer park skis are easier to land on BTW too.

FYI look at S&C right now
post #23 of 44
Quote:
Originally Posted by skier219 View Post
The overall length I gave was the linear length from tip to tail, measured by projecting the tip and tail position down onto my workbench surface.
Ok.....that sounds like point to point.

The commonly accepted way to measure is along the base/running surface, from tip to tail. The PE's should measure around 182 or something like that. The 179 measurement is a nominal sizing, which doesn't include part of the tail/twin.
post #24 of 44
Thread Starter 
Quote:
Originally Posted by viking kaj View Post
Rossi World Cup 9s 155

Dynastar Course Comp 66 176

Dynstar Little Big Fat 169

I'm leaning towards the 169 because if your analysis is right the PE in this length should ski like a 159 with a 14.5 meter radius on hard snow, should give her plenty of float in powder, and will be easier to get around on in the park than the 174.

My rough guidelines suggest that the 174 PE will carve about like a 160-162cm traditional ski and the 169 PE will carve like a 155-158cm ski. Here's what I get for the turning radius of each size:

179cm: 18.21m
174cm: 16.97m
169cm: 15.77m

(note, this assumes the tip geometries on the shorter skis are similar to what's on my 179cm PEs, which makes this a *rough* estimate). K2 puts the numbers this way:

179cm: 20m
174cm: 18m
169cm: 17m

Float among the three sizes is very similar for a 130lb skier according to my calculations:

179cm: 0.0062 psi
174cm: 0.0064 psi
169cm: 0.0066 psi

However, the longer skis put the float out further from the ski center, and this makes it more useful in my opinion.

In every other respect that matters, the skis will feel similar. So maybe pick among 169cm and 174cm based on the kind of groomed snow turning radius you think she would like, knowing the float and other characteristics don't change a whole lot between the two sizes.

Craig
post #25 of 44
Thread Starter 
Quote:
Originally Posted by Highway Star View Post
Ok.....that sounds like point to point.

The commonly accepted way to measure is along the base/running surface, from tip to tail. The PE's should measure around 182 or something like that. The 179 measurement is a nominal sizing, which doesn't include part of the tail/twin.

I think it varies from manufacturer to manufacturer (and even from ski to ski within manufacturer lines). Volkl clearly measures the Karmas the way you mention, as I get 184cm+change when I measure along the ski base from tip to tip with a flexible fabric ruler (I would call that measurement an arclength). They must have rounded up to 185cm. K2 seems to use point to point, as their 179cm PEs are 178.5cm point to point.

I think the important thing is to be consistent within a review, whichever measurement is chosen, or perhaps use both. I tend to think point to point is slightly more useful when considering float, as it projects the area of the tips down to give their horizontal component, which is what counts for float. Beyond that, the shape/geometry of the tip is probably important for how well the ski rides up to give the float, and the arc length is more appropriate for that. So both measurements have merit.
post #26 of 44
Quote:
Originally Posted by skier219 View Post
I think it varies from manufacturer to manufacturer (and even from ski to ski within manufacturer lines). Volkl clearly measures the Karmas the way you mention, as I get 184cm+change when I measure along the ski base from tip to tip with a flexible fabric ruler (I would call that measurement an arclength). They must have rounded up to 185cm. K2 seems to use point to point, as their 179cm PEs are 178.5cm point to point.

I think the important thing is to be consistent within a review, whichever measurement is chosen, or perhaps use both. I tend to think point to point is slightly more useful when considering float, as it projects the area of the tips down to give their horizontal component, which is what counts for float. Beyond that, the shape/geometry of the tip is probably important for how well the ski rides up to give the float, and the arc length is more appropriate for that. So both measurements have merit.
I know it varies between companies - it always has.

I'm telling you that the most common, universally accepted way to actually measure a ski is from tip to tail along the running surface........period. Just so you know. "Point to point" is not.

As far as I'm aware of, K2 is giving a theoretical length, where they do not include the rear tip.....they are saying the effective measurement is 179, if the ski had a normally shaped tail, so it can be compared to normal skis.

Not trying to pick a fight, just trying to eleviate some of the confusion you might be causing with your terms and measurements, there is lots of other info out there on the PE.

Also, I take issue with your assessment of the sidecut vs. ski length and turn shape. While the tip bend does go very deep into the ski, the sidecut does extend past what would be the normal contact point, well into the tip of the ski, by about 5 cm. A little bit on the tail too. Even when carving hardpack, this part of the sidecut will be engaged in the turn. Thus, you can't really say a 179 carves or skis like a 165-167cm, with any degree of accuracy.....infact, if it did, I sure as hell wouldn't like it. Mounted at 0, it skis like a 185-190 cm ski. This also puts into doubt your sidecut calculations, because you are using the true running surface length, and not the actual distance along the base from the widest point ot the tip, to the wide point in the tail. The 179 does feel like a 20m sidecut ski, and again, if it was actually 18m, I would notice it and not like it (yes, I can notice something like that, and can't stand sidecuts less than 20m...even by a small amount). The 179 PE is close enough to a 22m+ GS sidecut, to where I can get comfortable on it.
post #27 of 44
Thread Starter 
Quote:
Originally Posted by Highway Star View Post
I know it varies between companies - it always has.

I'm telling you that the most common, universally accepted way to actually measure a ski is from tip to tail along the running surface........period. Just so you know. "Point to point" is not.

As far as I'm aware of, K2 is giving a theoretical length, where they do not include the rear tip.....they are saying the effective measurement is 179, if the ski had a normally shaped tail, so it can be compared to normal skis.

Not trying to pick a fight, just trying to eleviate some of the confusion you might be causing with your terms and measurements, there is lots of other info out there on the PE.
I don't see how it matters -- I have six recent/current model skis in the garage, and they all have slightly different measurement conventions when spec'ing "length". I am sure some conventions are more accepted than others, but in the end they are all somewhat arbitrary. The important thing is to be consistent when comparing skis in a relative sense, which is what I did in this review of the PE and Karma. While spec'ing out the chord length (linear and independent of the ski shape) I thought it was natural to go point to point for the overall length, but that too was arbitrary -- I could just as easily have gone with the arc length. In future reviews I will include both for thoroughness. Either way, it doesn't change the important conclusion that the PEs have much longer tips and tails than the Karmas!

Quote:
Originally Posted by Highway Star View Post
Also, I take issue with your assessment of the sidecut vs. ski length and turn shape. While the tip bend does go very deep into the ski, the sidecut does extend past what would be the normal contact point, well into the tip of the ski, by about 5 cm. A little bit on the tail too. Even when carving hardpack, this part of the sidecut will be engaged in the turn. Thus, you can't really say a 179 carves or skis like a 165-167cm, with any degree of accuracy.....infact, if it did, I sure as hell wouldn't like it. Mounted at 0, it skis like a 185-190 cm ski. This also puts into doubt your sidecut calculations, because you are using the true running surface length, and not the actual distance along the base from the widest point ot the tip, to the wide point in the tail. The 179 does feel like a 20m sidecut ski, and again, if it was actually 18m, I would notice it and not like it (yes, I can notice something like that, and can't stand sidecuts less than 20m...even by a small amount). The 179 PE is close enough to a 22m+ GS sidecut, to where I can get comfortable on it.
Your points are fine, but again keep in mind the focus on relative differences between the two skis. All the numbers I gave are consistent between the two skis. The fact that manufacturers quote sidecut and radius differently means that there isn't going to be a direct comparison using each manufacturer's specs; as far as I am concerned, any reasonable set of metrics is OK as long as it's consistent and can be referenced. In this case, I determined the chord length by placing the skis base to base and marking the forward and rear contact points; this was something I could do the same way for both skis. Interestingly, some manufacturers spec sidecut dimensions at the widest and narrowest points of the skis, others do it at the contact points (chord length). Whichever method is used should be consistent in a comparison. Myself, I prefer the method I used as it gives the turning radius you'd experience with minimal edging required to engage the edge. The skier would have to lay the ski over beyond the minimal active edge to form a radius from the max width points if they are beyond the contact points of the chord. That seems somewhat arbitrary to me, as it depends on more than merely engaging the edge -- it would depend on the geometry of the tip/tail and the actual angle the ski is placed at. Not something that is easily determined with standard measurements!

The actual turning radius of the ski lies between these methods (ie, they are the upper and lower limits). Offhand, I don't know how much difference there is between the limits for a given ski, but I can make more detailed measurements for the PE and Karma and include both radius calculations to be more complete. That should address your concerns. I have a feeling the radius won't change much because the slope of the sidecut curve is fairly low and constant near the tip/tail contact points; as you go past the contact points, the increase in width is proportional to the increase in chord length by about the same amount as at the contact points themselves. It's not like the skis suddenly blossom in width past the contact points.

Going back to your point about the PE not skiing short, I do disagree with that. My 179cm PEs turn shorter than my 184cm and 176cm mid-fats and shorter than the 185cm Karmas, and that is apparent on paper (no matter what method you use for radius) and on the snow. For example:



(again, whether you agree with this radius calculation or not, it was done the same for all the skis; using the other radius calculation would not change the order/trend of the turning radiuses significantly in the comparison).

The formula for turning radius depends on the sidecut dimensions linearly, and on the chord length squared. Even with a modest sidecut, the shorter chord length of the PE has a big effect on the turning radius. That is what makes it ski short.
post #28 of 44
I can still ski with these right?(PE) I just picked some up and just wanted to have fun on them. Maybe I should return them? I'm exhausted!
post #29 of 44
Thread Starter 

Additional Info

OK, here are the complete specs for both skis:



I used two different methods for determining chord length [denoted as (1) and (2) in the table], and gave the associated sidecut measurements in both cases. The two methods do result in slightly different radiuses, and the skis are different in this regard; the PE turns longer (by 0.26m) with the dimensions from max width (method 2), while the Karma turns shorter (by 0.521m). The thing is, neither ski can put both max width points in contact with a workbench surface when edged; this is especially obvious with the PE, whose tip and tail max width points are 9mm and 7mm above the workbench surface, respectively. So I do not think method (2) using the max width points is as useful for spec'ing radius, and prefer method (1) which uses the ski's camber contact points to spec the chord and dimensions. It may not matter a whole lot, however, since both methods give similar turning radiuses within 0.25-0.5m (goes back to the suspicion mentioned in my previous post). The difference will surely be blurred in softer snow when the contact points are not well defined.

Regardless of the method used, the 179cm PE turns roughly a 3m shorter radius than the 185cm Karma despite similar overall lengths. This is consistent with the previous comparison on a relative level.

As mentioned in the original review, the 179cm PE measures 178.6cm point to point, and the 185cm Karma measures 180.5cm point to point. Along the ski base, the arc length measurement from tip to tail is 182.3cm for the 179cm PE and 183.5cm for the 185cm Karma. As before, the skis are less than 2cm apart in any of these overall length dimensions, but the shallower tip/tail geometry of the PE gives it over 10cm less chord length than the Karma based on method (1). The chord length based on method (2) adds about 16cm more effective running length to the PE, which reflects the longer soft snow "personality" of the ski mentioned in the review. For the same comparison, the Karma only gains about 4cm more chord with method (2). In fact, if you look at the Float Pressure numbers (lower numbers mean more float) the Karma only gains 3% float with the longer effective length from method (2), while the PE gains a whopping 12% more float. Dual personality indeed!

I hope the expanded set of numbers I provided satisfies everyone; on all points, they reinforce the conclusions in the original review.

Craig
post #30 of 44
interesting review, well done IMO. thanks for all your hard work.

I used your observations in part to make my decision to stick with slightly shorter PE's. well i bought the skis beforehand but now i don;t feel i made a mistake with the purchase as of yet.
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