Welcome! Ultralight backpacking is my passion, and keeping up on new technologies, gear, and techniques relevant to UL backpacking is what floats my boat. I'm always looking for the lightest, most functional gear to improve a lightweight or ultralight backpacking kit, and report my impressions and field testing results here. For hikers wanting to keep up on the latest and greatest ultralight backpacking gear, this is a good place to hang out. Also, there is a lot of information here (and on our informational website Southwest Ultralight Backpacking) on useful techniques and backcountry etiquette -- food for thought for hikers wanting to lighten their load and their impacts.

My goal for Ultralight Insights is to understand, test, and report on new technologies and gear of interest to lightweight and ultralight backpackers. It's a passion after all, so we just plain enjoy talking about it. I hope readers will add their own wisdom and comments, respond to my questions, ask their own questions, and correct me if I get something wrong. Happy hiking! Will

Sunday, August 18, 2013

GEAR REVIEW: Big Sky International Evolution 2P Tent

By Will Rietveld and Janet Reichl

When a backpacker is looking to save weight by purchasing a lightweight tent, she typically compares tent weight and features. A double wall tent is usually preferred by lightweight backpackers, and for a two person model, two side entry doors with vestibules is the most convenient. Nowadays, there are several two person double wall tent models weighing less than 4 pounds to choose from.

One way to go wrong in choosing a lightweight tent is overlooking tent dimensions and specific features. Some manufacturers make their tent lighter by making it smaller, for example, only one entry for a 2-person tent, less floor area, less headroom, and fewer features. Personally, I don’t like to play that game; I want a 2-person tent that’s roomy, fully featured, and lightweight.

Nobody does that better than Big Sky International. The Evolution 2P is a full-size free-standing roomy 3-season 2-person double wall tent with two doors with vestibules, four storage pockets, and total weight less than 3 pounds. And that weight includes stakes and aluminum poles.

The Big Sky International Evolution 2P tent weighs just 3 pounds, yet it’s roomy inside, full-featured, and well-designed.

Evolution 2P (Revision J)
Configuration Tested
SuprSil UL fly, mesh interior with clips, UL DAC aluminum poles, 8 stakes in sack (2 tubular stakes for vestibules and 6 titanium shepherd hook stakes), storage compression sack
3 pounds, 0.35 ounces (includes mesh interior, fly, poles, 8 stakes in stuff sack, 4 guylines, compression storage sack
Floor Dimensions
91” long x 53/47” wide x 42” high (verified) Area is 31.6 sq ft
Two side entry doors with vestibules, large mesh interior doors with 2-way zippers, 4 interior storage pockets, two closable top vents
MSRP as Tested
Other Options Tested
ShelterSaver groundsheet, grommet kit

Most Big Sky International tents are purchased ala carte, meaning that for each tent component (fly, poles, stakes, etc.) you have a choice from a list of options. As one would expect, the lightest options (such as UL fly fabric and composite poles) cost more to reduce tent weight. This is a really nice approach for knowledgeable buyers, because it allows them to purchase the exact configuration they want. Although the process can be a bit daunting for inexperienced buyers, choosing the basic configuration still results in a very lightweight tent. Hopefully this review will help with those decisions.

The Evolution 2P double wall tent is Big Sky’s flagship model. It first came out around 2005 and is now in Revision J, that’s nine updates since its initial introduction. Big Sky continually updates their tents to incorporate lighter and better components as they become available, and adjust the design. So, the current model is very refined.

The Evolution, like other Big Sky tents, is made of silnylon, which is silicone impregnated 1.3 ounce per square yard ripstop nylon. Big Sky offers two weights of silnylon, or SuprSil as they call it. Regular SuprSil is equivalent to regular Silnylon at about 1.3 ounces per sq yd; SuprSil UL is the lighter version at about 1 ounce per sq yd. There are many versions of silnylon, and the one that Big Sky uses is very high quality.

Another interesting point is that Big Sky tents do not need to be seam sealed like other silnylon tents. I tested that claim with a garden hose spraying 30 psi directly at the seams, without any leakage.

Side View. Both sides of the tent have a large vestibule and entry door, plus a large top vent. Door closed (left), doors open (right).

End views. Head end (left) and foot end (right). The head end has black stakeout loops and the foot end has red stakeout loops, so it’s easy to orient the tent when you set it up. The head end is 6 inches wider than the foot end.

The inside the Evo 2P has four large storage pockets (left), two at the head end and two at the foot end. Each side of the tent has a large closable top vent (right) to enhance ventilation. A top vent is a very important feature to look for in a backpacking tent because it utilizes the “chimney effect” to exhaust moist air from the tent.

Floor dimensions are generous by lightweight standards: 91 inches long x 53/47 inches wide head/foot x 42 inches of headroom (verified). Since the floor is slippery silnylon, it’s a good idea to paint stripes of silicone across the floor. Use McNett SilNet and dilute it with paint thinner to the consistency of pancake syrup, then paint it on. The seams on a Big Sky tent do not need seam sealing, which is a big plus.

The Evolution’s floor fabric is 30-denier silnylon. If you would like a more durable floor, order the Evolution 2P with the Eclipse 2P interior. The Eclipse has the same dimensions as the Evolution but has a 40-denier floor (polyurethane-coated ripstop nylon, seam taped); the heavier floor fabric adds 7.65 ounces to the weight.

My test tent came with the compact UL DAC Featherlite aluminum poles, which fold to a 14.25 inch length, a $7 upgrade. These poles are more compact (3 inches shorter) and  weigh 0.2 ounce more than Big Sky’s standard 17-inch UL DAC aluminum poles.

Field Testing
We tested the Evolution 2P on a number of summer backpacking trips in the southern Rockies, where we experienced lots of weather conditions including warm/calm nights, heavy rain followed by a calm night, strong winds, plus a few bugs thrown in for good measure.

Setup – Setup is easy and fairly fast, but not as fast as a single wall tent. 1) Lay the inner tent on the ground in the orientation desired (black stakeout loops on the head end) and stake the corners. 2) Lay the poles across the tent and connect one end to the grommets (or slide the poles through the sleeves if you have a tent with pole sleeves). Arch the poles and connect the other grommet ends. 3) Attach tent clips to the poles. 4) Lay the fly over the top (again, black stakeout loops on the head end) and hook to loops at the corners. 5) Stake out the vestibules. 6) Go inside and connect eight Velcro loops on the fly around the tent poles. And 7) stake out the four corner guylines and end/center guylines, using the four stakes originally used on the corners.

This full setup requires 8 stakes. We recommend a pair of tubular stakes for the vestibules and titanium shepherd hook stakes for the guylines.

The full setup, as described above, provides a bomber pitch ready for strong winds and wind-driven rain. It also fully extends the mesh interior so it doesn’t contact the fly, and allows maximal ventilation. For a quick pitch in good weather and a protected location, the tent can be secured with only two tubular stakes on the vestibules. However, in unpredictable backpacking conditions and to optimize the benefits of a double-wall tent, its best to go with the full setup.

Wind Stability and Ventilation – For good wind stability, it’s essential to attach the eight Velcro tabs on the fly to the poles. Also, we highly recommend getting the guyline kit when ordering the tent, and using them to secure the four corners of the tent. This requires some extra effort, but it results in a much sturdier pitch and tensions the interior mesh. Bottom line, the tent performs at its best if you do this.

Without the full setup (Velcro tabs not used, no guylines), in a strong wind the poles slide under the fly and the tent deforms badly, springing back after a gust. With the full setup the tent is rock solid.

The combination of a raised fly (about a 6-inch gap above the ground all around the tent) and two top vents provides maximal natural ventilation. This is as good as it gets. In good weather with a low bug count, it improves ventilation a lot to leave the inside mesh doors open at night. Under ideal conditions you can tie all the doors open for maximal ventilation and some star gazing.

Condensation is unavoidable on a calm/cool night following a rain. In a double wall tent the condensation is on the inside of the fly, so the interior mesh shields you from the moisture. You are exposed to condensation on the inside of the vestibules, but you can carefully unzip the door and flip it to the rear, where it will stick if the tent is wet. Bottom line, a double wall tent shields you from contacting condensation, but you still pack up a wet tent, unless you take the time to dry it out before packing it.

Livability – The Evolution 2P has plenty of room inside for two people plus gear, and headroom is abundant. Note in the photos above that the head end is very steep, and the foot end is also a very high angle. This means that essentially all of the interior volume is usable. The floor is 90 inches long and 53/47 inches wide (measurements verified) so there is extra space between the occupants and at the foot of the tent. Four really large storage pockets in the corners hold numerous smaller items to keep them handy. When the inside mesh doors are tied back, the interior of the tent really opens up, adding the space in the vestibules within easy reach

Fly-Only Option – By purchasing Big Sky’s groundsheet and grommet kit, or X-strap with grommets, the Evo 2P’s fly can be set up by itself, providing a lot of interior space and saving a little weight. This setup requires the fly, poles, stakes, groundsheet, and guylines, with a total weight of 35 ounces with the carry bag. In less buggy conditions this is a good way to go because it’s dry and roomy. However, the raised perimeter allows wind/breezes to pass right through, and it’s a single wall tent, so condensation may be an issue. In my testing on a very rainy 3-day trip, condensation was minimal because of the shelter’s excellent ventilation.

Mesh Tent Only Option – In good weather, pitching the tent’s mesh interior only provides protection from bugs and creepy crawlers, and allows some good star gazing. Simply set up the mesh interior with the poles and skip the fly.

The Evolution 2P is not the very lightest 2-person double tent to be found anymore. At almost 3 pounds, it’s a few ounces heavier than some of the newest lightweight tents featured in my Summer 2013 Outdoor Retailer Show shelter coverage in the blog post following this one.

What is hard to find however, is a lightweight tent that gets everything right. Many of the lightest tents are missing something – they have only one entry door, small floor area, small vestibules, no top vents, low headroom, or they use exotic materials that are very expensive. Frankly, it’s hard to find a tent that gets everything right.

The Evolution 2P is such a tent – it gets everything right. It’s easy to enter, roomy inside for two people, has great livability, lots of storage in pockets and vestibules, has great ventilation, and is very storm-worthy and wind stable (if you do a fully secured pitch, as described above). The Evolution 2P has received nine upgrades over the past eight years, so it’s very dialed in to make it as good as it can be. And the $450 cost (with options) is reasonable compared to other high quality tents.

The only downside of the Evo 2P is the time it takes to set it up securely. The extra setup time is due to its double wall design; a single wall tent like the Mirage 2P is significantly faster to set up.


  1. Will - Is the ground sheet option alone 36 ounces? That can't be right...what components were needed to set up the fly only configuration in your picture?

  2. Hi Philip, the fly only pitch requires the fly, poles, groundsheet with grommet kit, guylines, and stakes. Total weight is 35.65 ounces. It creates a very roomy shelter that's easy to enter and well-ventilated. But its open around the perimeter and there is no way to lower it to the ground to seal out bugs and wind. Best, Will

  3. Hi,

    What about a 6-inch gap above the ground all around the tent? When raining hard, the rain dont comes in tent under rain fly and comes to ground sheet? What distance between ground sheet and rain fly? Its possible to build tent with both inner and outer fly sheets?

    1. Yes, the bottom of the fly is 6 inches above the ground for ventilation purposes. If you are camped on bare ground, when it rains hard you get splashback onto the sides of the tent, which is the lower fly and the bathtub floor. It rarely gets inside the tent. I prefer to camp on vegetation to avoid that problem, but often you don't have any choice.

  4. Has big sky fixed their production problems that they used to have according to many old message board threads?

    1. http://bigskyproducts.com/Big-Sky-International-product-availability.aspx

    2. Early on, Big Sky was overly optimistic about the arrival time of products from an Asian manufacturer, so they accepted orders and payments assuming the product would arrive any day. They got in a big bind (and learned a valuable lesson) when the shipments did not arrive, wait time drug out, and buyers got really impatient and upset. Nowadays Big Sky has their own factory that produces an ample supply of tents. However, there are still some wait times because Big Sky is continually updating their products, and production runs are smaller. That's good news because the tents are highly refined, but bad news if you are in a hurry and they are temporarily out of supply. Their website now has a "Click here for product availability" link so you can see if the tent is in stock and what configurations are available.