TerraNova Ultra 20 cuben backpack

This review isn't on the TGO website yet. Material in the current paper edition doesn't usually appear on the website until a few months later.

However some reviews by me will now appear directly on the TGO website – and may appear later in the paper magazine. The first of my reviews – on the Paramo Torres Sleeves and the Rab Infinity down jacket – are on the website now.

Bottom line. Eddie Meecham likes it. Plans on buying himself one as soon as they are available. Have the TGO copy here if you want a specific answer.

I didn't realize cuben was born from the America's Cup. Fascinating bit of the story!

This pack looks nice, but the article indicates it's made from a thin variant of cuben which doesn't seem like a great idea to me. A thicker variant of cuben like Zpacks uses isn't much heavier and would add a lot of life to the pack. My Zpacks Zero + options pack made of 1.5oz cuben weighs 140g (compared to 115g) and it's much more durable and it has additional features of a center pocket and two water bottle pockets…and I'm sure it's way cheaper.

x

"…and I'm sure it's way cheaper."

The Zero is cheaper, but only because the US dollar is currently so weak: from my point of view, landed in Australia, and specced to the same level (if "specced" is the right word) they're fairly similar in cost.

I'm sure that 1.5 cuben is adequately durable but I'm still perplexed by why you would ever use that weight of cuben. The cost to benefit is nonexistent for cuben that is in the same weight range as silnylon (in my opinion). Its just a novelty at that point.

I've spent a great deal of time deconstructing Cuben Fiber numerically to work out the weight of the mylar film and the spectra fibers in isolation from one another. Luckily CT publishes very good and accurate data which made this fairly straight forward. I then used those same breakdowns to construct different fabrics which are not currently manufactured (at least not that our community knows about). Some of the most interesting appear in the table below. Joe at ZPacks has felt them out and they will make any fabric we want available in 99 yard rolls which is a substantial investment to be sure.

Hypothetical .18 Cuben Fibers

I think the most interesting fabric for a backpack would be CT1K.18 since it would provide a substantial weight decrease as compared to silnylon, would have the same abrasion resistance as the currently favored 1.43 oz/yd² CT5K.18 and would still have more than enough tensile strength to cope with the very mild loads that an UL backpack must cope with.

Just so everyone knows, Quest Outfitters has some stock of the CT0.6K.18 right now. It is pretty strong stuff, and looks like a great material to make a bivy floor.

And I'm pleased to note that Quest states a weight of 0.69 oz/yd² and my calculations predicted 0.68 oz/yd²! I think this would be the ideal material for a tent floor.

"I'm sure that 1.5 cuben is adequately durable but I'm still perplexed by why you would ever use that weight of cuben. The cost to benefit is nonexistent for cuben that is in the same weight range as silnylon (in my opinion). Its just a novelty at that point."

I totally disagree. Cuben is so much better than silnylon. 1.5oz cuben doesn't stretch, it's totally waterproof and most importantly, it's way stronger/durable than silnylon. A 1.5oz cuben backpack is built to last. A silnylon backpack needs to be babied to last an okay lifetime. It's the difference between disposable gear and durable gear.

With a backpack where you are only using 1-2 yards of material, I think it makes a lot of sense to spend the extra $20-$40 in material cost for cuben.

With that said, Terra Nova appears to be using quite a light variant of cuben with this pack, and I don't think that makes a lot of sense. It's basically the same cost and the difference is only a few grams and you are giving up a lot of durability.

Wouldn't the spectra weight be pretty unimportant for use as a ground cloth or floor? There would be very little tensile force being applied, as it's just laying on the ground, so wouldn't it be ok to use the lowest spectra cuben with the thicker Mylar?

I mostly think so as well but people I trust like Joe have stated that they feel that the spectra helps with abrasion resistance. I don't know about abrasion but I can believe that it helps with puncture resistance which is important. I've now come to think that a nice beefy mylar layer for abrasion coupled with a minimal (but not nonexistent) spectra mesh for puncture resistance would produce a bomber tent floor or backpack with an absolute minimum weight. I can't wait until someone is brave enough to make one out of CT0.6K.18 and report back after some nights in the woods. I plan to perhaps this summer but lately my DIY plans have been getting trampled by work/life.

To echo what Dan wrote: I have both a ZPacks Zero in 1.43 Cuben (CT5K.18 to be precise) and a Gossamer Gear Murmur in 1.35 oz silnylon and the zero is clearly more robust/durable than is my Murmur. Not to mention the zero is 4 ounces lighter at 3 oz as opposed to 7!!!

The spectra in cuben prevents any tiny holes/tears from spreading, so indirectly it makes the groundsheet more durable. It's amazing when you play with cuben….the outer edges of a roll of cuben contain no spectra and you can easily mutilate the mylar, but if you try the same thing where the spectra exists the cuben is far stronger. This may not show up easily in simple abrasion/rubbing tests, but it makes the cuben much harder to puncture and it prevents holes/tears from enlarging or even starting.

Good work on the chart Chris!

Hypothetical:

Cuben pack that would last 50 trail days at 3oz?

OR

Same pack and features in heavier cuben for 5oz that would last 100+ trail days?

''I can't wait until someone is brave enough to make one out of CT0.6K.18 and report back after some nights ''

Done , except for the actual trip, have laid it out on gravel though, see my cuben tent thread here somwhere.

RON:

id rather carry your dyneemaX and last the Triple Crown.. but that's just me :)

Ron, without a doubt I'd opt for pack B. 50 days is far too short of a lifespan.

"I then used those same breakdowns to construct different fabrics which are not currently manufactured (at least not that our community knows about)."

That's very cool Chris.

So, we UL'ers starting out by searching out and adopting fabrics like silnylon and cuben that weren't then being used for backpacking gear – and now we're creating theoretical fabrics for the manufacturers to make. I guess that is the next logical step.

"And I'm pleased to note that Quest states a weight of 0.69 oz/yd² and my calculations predicted 0.68 oz/yd²!"

It's kind of like discovering an element by filling out the periodic table by extrapolation.

Thanks Ron! I see no reason not to make both available. There must be many people like me who work far too much to allow a thru hike on any trail (until I retire) but when they do get into the woods have fun doing it as lightly as possible. It would take me several years to log 50 days on a backpack so I'll take option A please! I would think that weekend warriors outnumber thru hikers by a comfortable margin. I don't mind spending $100 every few years on a backpack.

BTW, there is nothing hypothetical about my ZPacks Zero which weighs 83 grams even made out of CT5K.18. The same pack made out of CT0.6K.18 should weigh about half (hard to scale because of strap padding, webbing, buckles, etc) and I think last me several years at my current usage rate.

Like the order for breen cuben a year ago, if we could get together 99 metres of a special order cuben cubic tech would make it for us. Just to see if there is enough interest I will give this rolling ball a little push. 3metres for me. Anyone else?
I already asked Jon Holweger whether 18 (micron?)mylar is the most abrasion and pierce resistant membrane that cubic tech knows of, for that weight.

Each of the two Mylar layers is 18 mils or thou depending on your background. To be very formal each Mylar layer is 0.018" thick.

I think there's only about a yard of cuben in a Zero backpack (depending on the size), so even with really light (ie. CT0.6K.08) cuben you'd probably not save more than an ounce. With a pack a good portion of the weight is in the padding, straps, fasteners, cord etc, so I'm not sure switching to a fabric lighter than 1.5oz cuben really makes sense. Even if you don't put on a lot of days on the trail, going with 1.5oz cuben adds a margin of safety against pack failure. The material is way stronger, so you've got much less risk of a shoulder strap tearing off, a seam tearing open or a fall onto a sharp rock cutting the pack open.

I'm super excited about my Zero pack. It's CT5K.18 (1.5oz) cuben with 2 water bottle pockets, a rear mesh center pocket and simple webbing hipbelt for 140g or 4.96oz. It's got everything I want for 1-2 night trips. I think it's a good balance between simplicity and functionality.

Joe at Zpacks makes a nice cuben backpack and its smart of him to use the CT5K.18 material for added durability. If Joe's pack will last 100 days then the Terra Nova built with "very thin" cuben will last 10… Terra Nova better hope they buy some sort of warranty insurance because they are going to need it using such a light weight material.

Maybe Terra Nova should leave the gear building up to the "fringe"