Krux vs Xcurve, a photo essay

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Apr 9, 2012
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Fishhook, Alaska
I’ve been using Stone Glacier packs since the first ones hit the market. I’ve had my hands on most of the bags and used both the wrap belt and 3 pc belt versions of the frame. Recently I’ve had several people ask me about the current Xcurve frame. I don’t have one myself, but arranged to borrow a preproduction version from a member here (thanks snowcamoman). This isn’t a review exactly, but with both frames in hand I thought I might be able to highlight the differences between the two. Consider this more a pictorial than an actual review.

First off, the Xcurve is VERY closely related to the older Krux. These aren’t just close cousins, they are more like brothers. Kurt has mentioned this before, but when I looked at them side by side, they are clearly the same basic frame and harness with a few evolutionary upgrades.


Krux on the left, Xcurve on the right


Rear view. Size, shape, and basic construction are identical.


The main differences between the two are essentially:
1.) New curved stays
2.) Modified straps on the hip belts

Other differences are all minor tweaks, including standard “power pulls” and some small reinforcements and adjustments. Lumbar pad is now rubber coated fabric vs. the mesh on my older Krux although I think the current Krux may be the same way.
First thing I did was put them on the scale. My old Krux weighs 2 lb 8 oz. The Xcurve adds half a lb to come in at 3 lb 0oz.

More to come.
 
OP
Yellowknife
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STAYS

I pulled a stay out of each frame to compare. The original stay used in the Krux frame is a straight solid carbon fiber rod. The new Xcurve stay consists of 3 sections of CF rock solidly epoxied into titanium tubing at the bends.







The change in stays are clearly the main contributor to the difference in weight. The new stays are over double the originals and each pack takes four so it adds up.




 
OP
Yellowknife
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LUMBAR

The lumber pad on the Krux 3 pc belt is tapered to fit a person’s lower back. The new Xcurve matches the lower back curve with the frame angle, and has a pad that is slightly thinner and generally single thickness.


Krux lumbar with tapered pad


Xcurve with curved frame and a rounded pad

BELT

The new belt set up is one of the larger changes. Essentially the old belt used the fairly traditional system of a single wide strap over the belt as the primary tension piece. Same as used by Mystery Ranch, Exo, Barneys, Kuiu and countless backpacking packs. The new one uses a two straps, with the idea that it would increase the “cupping” of the belt and lead to a better fit.



And illustration of how it works in real life. With the original Krux belt cranked down, you can see the padding kind of flares top and bottom.



With the new belt, this isn’t the case.




I did find that the amount of “customization” is pretty limited. The straps are close together and the foam is stiff enough that you aren’t going to significantly change the amount of cupping you get. However, it is enough to be a difference from the original.


How important is this? Dunno. I’ve never personally had an issue with the standard belt, even loaded heavy. The center strap rides right above my hip bone and it all fits nicely. If you tend to get bruising on the points of the hip bone, or have issues with the belt sliding down this may be just the answer. Only real disadvantage I see is the extra straps (I’m not a fan of more straps than needed).

Side note and minor rant here on the “power pull” belt. I’m personally not a fan and never understood the hype. Like many of these systems, the SG one locks at the buckle, and then tail just threads back through a loop on the belt in a sort of primitive pulley system. For me, I’ve never had an issue cranking down a normal belt as tight as I want it to go with a quick two hand tug. And that’s even with my scrawny non-gym biceps. The double back through doesn’t really help since I still have to pull on it with one hand and kind of work the webbing through the buckle with the other. Don’t have one in hand right now, but believe Kifaru, Exo do the same type systems. The Mystery Ranch and I believe the Icon Pro packs are different, with the locking portion on the belt and a free sliding buckle. That kinda makes more sense to me… but what do I know. Either way, all I’ve ever found them to be is extra webbing and junk. Maybe someday an awesome one will come along and convince me I’m wrong.

 
OP
Yellowknife
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Finally, I rounded up 55 lbs of assorted junk and loaded it down for the weekend dog walk to get a quick subjective “feel” evaluation. The usual dog trot is just under three miles and 800 ft of elevation gain, so hardly a serious test, but I’m pretty familiar with the Krux, and wanted to see if any significant differences were obvious.



Generally, there are a few differences but both very much feel like you are wearing a Stone Glacier. Much more similar than different. The curved frame does ride a bit closer and with more contact to the back and certainly sits a little more solidly into the lumber. I’m guessing that becomes a positive when really loaded down, but for lighter loads it limits spine movement more and just kind of made the whole system feel “stiffer”. I think I have a slight preference for the straight stays for my typical use, but might change my mind if I was mostly doing heavy packing. The hip belt was very comfortable at that level, but then again… so was the old one for me.

My opinion is that if the Krux already works for you, then then the gains are probably minimal. If you have issues with sliding belt or bruising hips I’d bet this is a nice improvement. Personally I’m happy with the 8 oz lighter and simpler Krux, but there are no obvious flys on the new Xcurve.
 
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Great review and just what I needed. I have been eyeballing new packs. I'm almost to the point of ordering one from each major manufacturer, SG, Kifaru and MR.

When you said the hip pad "center strap rides above my hip bone", does this mean that the buckle is over top your navel? Or does the pack belt ride on top of your pants belt?

Sorry for the questions, I'm just having a hard time figuring out exactly where the belt/pads are supposed to ride.

Sent from my SCH-I545 using Tapatalk
 
OP
Yellowknife
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When you said the hip pad "center strap rides above my hip bone", does this mean that the buckle is over top your navel? Or does the pack belt ride on top of your pants belt?

Speaking only for myself, the pack belt overlaps my pants belt but is centered higher and the buckle is just under the navel.
 

oenanthe

WKR
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Thanks for the info - good stuff!

I've been using the Krux for a few years, and my only beef (and it's a minor one) is that the shoulder straps could use a bit more padding. The foam is not quite dense enough and the straps end up cutting in to my shoulders. It's not unbearable but it is annoying. I've heard this from other Krux users too.

Would you mind taking a careful look to see if the foam density or thickness has changed?
 
OP
Yellowknife
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Would you mind taking a careful look to see if the foam density or thickness has changed?

Honestly couldn't tell you. My straps were replaced late last fall, and this pack was a pre-production that appears to have been partially constructed from a Krux at about the same time. Consequently, the straps on these one's are identical. Would have to ask Kurt if there was a difference in the current version.
 

sr80

WKR
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Thanks for the info - good stuff!

I've been using the Krux for a few years, and my only beef (and it's a minor one) is that the shoulder straps could use a bit more padding. The foam is not quite dense enough and the straps end up cutting in to my shoulders. It's not unbearable but it is annoying. I've heard this from other Krux users too.

Would you mind taking a careful look to see if the foam density or thickness has changed?

the shoulder strap foam is definetly a little more dense, and not as flimsy. They might be a hair thicker, but nothing crazy. I didnt have any issues with my shoulder straps on my old krux frame. I noticed with the x-curve i had to angle my shoulder straps outwards away from my neck a little bit with the denser foam. Not sure if that helps
 

MT_Wyatt

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the shoulder strap foam is definetly a little more dense, and not as flimsy. They might be a hair thicker, but nothing crazy. I didnt have any issues with my shoulder straps on my old krux frame. I noticed with the x-curve i had to angle my shoulder straps outwards away from my neck a little bit with the denser foam. Not sure if that helps

I've actually had to do the same thing.

The shoulder strap foam is most assuredly thicker on the new frames, Kurt told me 20% thicker and 40% denser.

Another key belt difference is the switch to a dual density foam, which I am a huge fan of.
 
OP
Yellowknife
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Another key belt difference is the switch to a dual density foam, which I am a huge fan of.

The early copy I have here may not have that. If it does, I can't feel the difference. Guess I should have been careful about making statements about a pack design that wasn't finalized yet!

Either way, I'm good. The foam in my old hipbelt has held up well. The old shoulder straps did eventually start getting thin after three years of pretty steady use. Never caused me any issues, but they were slowly wearing out. Current ones seem good to go. Only thing I wouldn't mind upgrading is going from the mesh fabric lumbar pad to the newer rubber coated fabric. There are pluses and minuses (rubber coated is going to be hotter, sweatier), but seems worth it for those occasions when I'm forced to wear it over goretex and could use a little more traction.
 

Trr15

WKR
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Feb 16, 2014
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Thanks for the write up. Very well done. I just picked up a Stone Glacier w/Krux frame. I've experimented with most of the other popular pack systems, but this will be my first test of the SG. Looking forward to trying it out while bear and shed hunting.
 

oenanthe

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Thanks to YK, Wyatt, and sr80 for the detailed info. I may contact Kurt and see how much a shoulder strap upgrade would run.
 

luke moffat

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Feb 24, 2012
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Great write up YK!!! Nice breakdown and now I know what I missed by jumping straight to the XCurve ;)
 

pdp

FNG
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Jun 17, 2017
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Interesting...just agonizing over which pack to buy. Paralysis of analysis.
 

Blackcow

WKR
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central Az.
And now they have a "new" xcurve. They sent me an email yesterday. I think just the stays are different, supoosed to be stiffer, and overall 3oz less.
 

SCOGS

Lil-Rokslider
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Apr 4, 2016
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In case anyone is interested in purchasing just a set of the new x-curve stays, I contacted SG and they said they would sell stays only, but they're $200.
 
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