What makes a pack an "alpine climbing pack"?
Alpine climbing packs are usually simpler in design, lower profile, and offer the features needed to attach alpine climbing specific gear - namely ice tools / axes, crampons, and a climbing rope. They differ from backpacking packs or hiking daypacks in that they are intended for use both hiking (on approach) and while climbing technical terrain - be it easy ridge scrambling, steep rock, or ice couloirs. Generally speaking, and alpine climbing packs may sacrifice hiking comfort and frame support for increased climbing performance.
What's the best size?
The first step in choosing the right alpine pack is deciding on what capacity is best for your climbing objectives. No single pack is perfect for every climb, and for this reason the best performance is achieved by owning two packs - one smaller and one larger - allowing you to choose the appropriate capacity for the trip at hand. An alternative and cheaper option is to purchase a midsize-capacity pack in an attempt to get the maximum versatility.
30 Liter packs
A 30L pack is the perfect capacity for car-to-car alpine climbs and one-night trips where you have a super light bivy set-up. 30L packs are compact, low profile, and are therefore much more comfortable to climb technical terrain with than larger packs. If you do the majority of your alpine climbing over the weekend, perhaps mostly long days car-to-car, the climbing performance, low-bulk, and low-weight of a 30L pack will serve your needs much better than a larger pack will. Using a 30L pack on climbs longer than one day does require traveling light due to limited pack space. Traveling light will make climbing technical terrain much more enjoyable however.
40 Liter packs
This is a fairly versatile capacity. Not too big, not too little. If you take lots of trips that are of a moderate length, perhaps 3 days for example, then you will best appreciate this size pack. With the extra 10 liters or so of capacity over a 30L pack you can much more easily accommodate the items you need to live comfortable in the mountains - stove, fuel, shelter, and all the extra food. 40 liters is still relatively small however, meaning that many 40L packs have simple and light frames and are thus still reasonably comfortable to climb with. A 40L pack may also be the best size if you frequently partake in winter alpinism and/or ice climbing. All the extra clothing layers, you'll likely be taking in winter tend to fit more easily in a pack of this size than a small 30L pack. If you want to purchase only one alpine climbing pack, and take multi-day trips occasionally, a 40L pack is likely the best choice. We recommend having a 15-20L pack as well for day-long rock climbs, as it will feel much better on your back than your 40L pack.
45 Liter plus packs
Packs of this size are intended for multi-day alpinism. In our opinion most people are better served by a smaller alpine pack since the bread and butter of most people's mountain climbing happens on the weekend or the occasional day off work. A pack of this size is a good choice if your taking an extended trip and can pair it with a superlight and packable "summit pack" or if you are attempting a long route in one of the "greater ranges" of the world.
What materials are used?
Another differentiator of a quality daypack can be found in the materials used. Here is a quick fabric overview:
1. Nylon is frequently used because it withstands abrasion and tearing. Nylon twill, which features a sturdy diagonal weave, is also commonly used.
2. Ripstop fabrics (nylon or polyester) are woven in a manner that creates box- or diamond-shaped patterns, creating a reinforced grid. Such "ripstop" fabric inhibits a tear from expanding beyond its point of origin.
3. Kodra fabrics (usually nylon) use high-tenacity fibers to enhance resistance to abrasion and tears. Their downside: The burly fibers tend to be heavy. Kodra is a generic name for such fabrics; the brand-name variation is Cordura.
4. Nylon oxford is a light, smooth fabric (characterized by a plain weave) that has been used in pack construction for decades.
5. Nylon/polyester blends are principally used to provide different colors within a single fabric. It's a fashion thing.
6. Hypalon is flexible synthetic rubber used to reinforce areas of high abrasion, often the edges or key touch points of packs. It is sometimes used to create patches. It is used sparingly on packs due to its weight.
Just as significant as the type of fabric is the fabric's denier. Denier is a unit of fineness for the yarn of a fabric. As it relates to a pack, denier influences its abrasion resistance and, subsequently, its weight. Higher abrasion resistance comes with a higher denier fabric, which includes a corresponding higher weight. Packs made for the minimalist or ultralight explorer may use fabrics as light as 70 denier. Rough, tough ballistic nylon, meanwhile, is often rated 1,600 denier or higher.
Fabrics often feature 1 of 2 coatings:
Polyurethane (PU) is the standard coating applied to the interior walls of packs. It provides significant water resistance (though not waterproofness—so if you dunk your pack in a lake, its contents will eventually get wet).
Silicone is a coating (or impregnation) used on lightweight, low-denier fabrics to minimize weight. It provides very high tear strength, though silicone can break down faster than a PU coating. PU coatings may also provide better water resistance.
What to look for durability?
The two critical features on any backpack that are most prone to wear and tear are the straps and zippers. Look for double stitching, good quality metal zippers, and buckles that don’t feel flimsy or fragile. You can pretty well judge how prone a zipper is to locking up just by trying it a few times back and forth.
Good backpacks have ventilation systems or netting that keeps the load off of your lower back so that your clothes will not sweat through. While this certainly helps comfort, do take more care as these are slightly more prone to getting torn up than just a simple back pad.
Tip: Measure your torso
Before you even start shopping, determine your torso length, so you can find the proper size pack for your body. Nothing is more important in fitting a large-capacity backpack because without the proper measurement, your shoulders, back and hips will not bear the load correctly, causing discomfort and, potentially, injury. To do this, you’ll need a friend and a soft tape measure or a length of string. Follow these three steps:
1. Tilt your chin down so that the C7 vertebra at the base of your neck protrudes. This is the starting point of your measurement.
2. Put your hands on your hips and use your thumbs to feel for the top of the iliac crest. Draw an imaginary line between your thumbs. Where this line intersects your spine is the end point of your measurement.
3. Have your friend drape the string or tape measure along the contours of your spine between the two points. You now have your torso length. (Most adults have torso lengths that fall between 16 and 22 inches.)
A note on women’s packs
These aren’t just smaller men’s packs in pretty colors. Good women’s packs have subtle but important fit differences that can really improve comfort for women: shoulder straps that are closer together, thinner, and more tapered to meld with narrower shoulders, and hipbelts that are canted to better cup women’s hips.