背包选择指南（转载请注名：卡拉奇单峰驼翻译）

How to Choose
　　
　　http://www.sportextreme.com/Se_Shop/HTC/Climbing/Backpack/Backpack.page.index.html
　　
　　
　　 Move on to:
　　Quick Read
　　Step 1: Decide how long and where you're going
　　Step 2: Choose a frame design
　　Step 3: Choose the Right Capacity?
　　Step 4: Choose a loading design
　　Smart Features
　　
　　There you are, scaling the lofty peaks of some noble mountain range. Gradually your mood begins to sour as the snazzy-looking, ill-fitting pack on your back starts to feel like a sack of potatoes. "But the industry polls said it was a great pack!" you protest.
　　
　　If you'd like to avoid that scenario, do some research to find the pack that's right for you. No doubt, there is a backpack that will suit your torso length, backpacking plans, and budget. And after several days on the trail, you'll be glad you took the time to choose the perfect one. Then, as you walk under the sun and the stars, you won't even notice that house on your back.
　　Quick Read: How to choose Backpacks
　　Choosing the right backpack is all about choosing a back that fits your needs! So before reading on take a moment to think about what you need a back for, you don't want a 7000 cubic inches (ci) monster back for a one day hike or even worse a 2500ci back for a 10 day hike. Done thinking? Okay read on!
　　
　　
　　Up to 3000 cubic inches is for one day trips where you don't have to carry tent, sleeping back.
　　3000-4000 cubic inches is for 2 days trips where you overnight.
　　4000-5000 cubic inches backs are good for up to 3 days of overnight camping.
　　5000-6000 cubic inches is good for up to a week outside.
　　6000 plus cubic inches for long trips a week or more.
　　
　　
　　More movement than External
　　Better balance
　　Better fit and comfort
　　Cost more than external
　　Less ventilation
　　Fewer storage compartment
　　Good for:
　　Climbers/Mountaineers
　　Peack-baggers
　　Skiers
　　Off trail
　　
　　Can carry more than Internal.
　　Cost less.
　　It's not possible to squish in small places
　　Gives less movement than internal
　　Better ventilation
　　Good for:
　　Beginning Hikers
　　Hikers with heavy loads
　　
　　
　　Top-Loading: Top-loading packs have one big hole at the top. Pro: These are stronger and more moisture resistant than panel-loaders. Con: They require more careful packing than panel-loaders, both to balance the load and to make items easily accessible.
　　Panel-Loading: These have a large U-shaped front zipper, allowing access to more of the pack. Pro: You can find things faster, and don't have to pack as carefully. Con: You can't pack this as fully as a top-loading model, and zippers can fail.
　　Hybrid-Loader: The best of both worlds. Usually a top-loader with vertical side zippers.
　　
　　Step 1: Decide how long and where you're going
　　The type of trip you're planning will help to narrow your choices. Here is a range of possible outings:
　　
　　An overnight in a campground You probably only need a daypack for day hikes, if you can set up camp by your car.
　　
　　A weekend on the trail in an area with a temperate climate.
　　
　　Five to seven days on a trail without any access to camping facilities or resupply.
　　
　　A longer (10 days or more) trip in areas where you need to carry your own water, or where you may encounter severe storms.
　　
　　Step 2: Choose a frame design
　　 Long-haul backpacks (suitable for 2-day trips or longer) are known as frame packs, meaning a metal frame supports the packbag and helps focus the weight where your body can most effectively carry it - on your hips. Manufacturers offer 2 styles of frame packs: internal-frame packs and external-frame packs.
　　
　　
　　Internals feature a narrow, towerlike profile and integrate their framework inside the pack, behind the shoulder harness. The frame usually consists of "stays," or flat bars, about an inch wide and 1/8-inch thick. Stays are usually aluminum and are configured in a V-shape. Alternative frame materials (such as composites) and stay-alignments (parallel, X-shaped; U-shaped) are sometimes used. Stays are removable and can be shaped to conform to your torso.
　　
　　Internals are popular packs with many advantages:
　　Flexibility Stays make internals stiff, but not rigid. This allows the pack to more easily move in harmony with body movements, a big plus for climbers and skiers.
　　
　　Balance Internals hug your body. This holds your equipment closer to your natural center of gravity and helps you keep your balance when it counts - for example, while you're scooting across a log above a stream.
　　
　　Stability Compression straps are everywhere on an internal. You use them to cinch down your load and keep individual items bunched together. This keeps them from shifting and throwing you off-balance if you make any abrupt moves.
　　
　　Maneuverability Because internals feature a slimmer shape, it's easier to swing your arms freely - another reason why these packs are popular with climbers and Nordic skiers. This narrow profile also helps hikers whenever they have to squeeze through tight spots or when they're bushwhacking through thick brush.
　　
　　 Adjustability Internals use suspension systems (involving the shoulder harness and hipbelt) that can be adjusted more precisely than external-frame systems.
　　
　　The downside of internals:
　　The black hole
　　Most internals have 1 cavernous main storage compartment, plus a separate section for a sleeping bag. Other than a lid pocket, nearly everything gets stuffed into that single, deep compartment. So, if it's necessary to find 1 particular item during a rest stop, you may have to hunt a while to locate it.
　　Hot stuff
　　You'll sweat more wearing an internal because it rides so close to your back. The design offers little room for ventilation.
　　Cost
　　Internals typically cost more than externals of a similar size.
　　Which people are better suited for an Backpack with internal Frame?
　　Climbers/mountaineers
　　Scramblers/peak-baggers
　　Skiers
　　Off-trail (cross-country) hikers covering rough terrain
　　Why? The snug fit of an internal allows your load to move with you, helping you stay balanced and agile on uneven terrain. Recreational backpackers have also grown to prefer internals, valuing their comfort and versatility. Internals have emerged as very popular general-purpose packs, typically outselling externals by a sizable margin.
　　
　　
　　Externals connect a packbag to a rigid frame made of aluminum tubing. Externals ruled the backcountry until internal-frame design was introduced in the late 1970s. Internals have surged in popularity, yet externals are still a great choice for transporting heavy loads along trails. With an external, the pack's weight sits more squarely on your hips; with an internal, the back, shoulders and hips share the load.
　　
　　The advantages of externals:
　　Cooler to carryAn external's load does not sit flat against your back, allowing air to circulate.
　　Easier to packExternals feature at least 2 main compartments plus several side pockets. You can organize your gear into "zones" and locate it more easily.
　　Heavy loads won't sagThey might in an internal, depending how you pack it. Plus, since your center of gravity sits higher in an external, it's easier to walk upright.
　　CostYou'll pay less for an external.
　　The downside of externals:
　　
　　Minimal agility They tend to make you walk more stiffly, making externals cumbersome when you try to walk off-trail. Attempting to scramble up rocks or hop across a boulder field while wearing one is difficult, even unpleasant.
　　Poor traveling companions Sometimes you can squish a loaded internal into a car truck or back seat; an external frame won't give an inch. Plus, in the luggage-transport systems of airports, externals sometimes can take a pounding.
　　Which people are better suited for an Backpack with external Frame?
　　Beginning hikers
　　Hikers hauling heavy loads over easy to moderate trails and terrain
　　Why? Externals appeal to juniors and beginners because they cost less. For people toting monster loads, the frame becomes an efficient extension of your upper thighs and pelvic region - an area of stout bones and thick muscle groups that are well-suited to the task of bearing the weight of a backpack. Are externals becoming obsolete? Don't count on it. Tradition is on their side, and they're a great bargain.
　　
　　 Rucksacks are a third category of overnight packs. These are usually frameless packs (some models include a single stay) that can store between 2,500 and 3,500 cubic inches of gear, enough for 1 or 2 nights - or more, if you are an ultralight specialist. These are essentially overgrown daypacks and often feature lightly padded backs. They are popular with skiers, trail-runners, rock scramblers and peak-baggers.
　　
　　Step 3: Choose the Right Capacity?
　　As the phrase goes, your numbers may vary. But here's a general guide for internals:
　　
　　
　　Up to 3,000 cubic inches: Good for day hiking or a 1-night trip in warm weather where your supplies will be minimal.
　　3,000-4,000 cubic inches: Enough space for 1- or 2-night trip. You can go even farther if you team up with a partner who could help carry the load of shared items.
　　4,000-5,000 cubic inches: Generally good for up to 3 days of overnight camping.
　　5,000-6,000 cubic inches: Can accommodate up to 6 days of overnight camping. The lower end of this range is good for most backpackers. Don't buy too large a backpack, though, if you don't anticipate needing the space. The more compact and lightweight your load, the better.
　　6,000-plus cubic inches: For long hauls lasting a week or more.
　　
　　
　　Capacity figures for internal and external packs vary significantly. Sleeping-bag storage accounts for the discrepancy. Internals carry sleeping bags in a special compartment behind the hipbelt, and synthetic bags can consume 2,000 or more cubic inches of a pack's stated capacity. With externals, bags are usually strapped to the underside of the packbag. This does not influence the pack's capacity figures.
　　
　　
　　Not every manufacturer measures cubic inches the same way. So one company's measurement of 4,000 cubic inches may differ a bit from another company's calculation.
　　
　　
　　 Internals tend to be a touch lighter, but the differences are minimal. Large packs can weigh up to 8 pounds. That's 8 pounds on your back before you add any gear! This should remind you to buy a pack that fits your ambitions. If you hike only modest distances, you don't need a monster pack.
　　Step 4: Choose a loading design
　　Again, there is lively debate on the virtues of each design, but the bottom line is the same--there's always a trade-off. Every good aspect has its negative result.
　　Top-Loading: Based on the traditional rucksack, top-loading packs have one big hole at the top. Pro: These are stronger and more moisture resistant than panel-loaders. Con: They require more careful packing than panel-loaders, both to balance the load and to make items easily accessible.
　　Panel-Loading: These have a large U-shaped front zipper, allowing access to more of the pack. Pro: You can find things faster, and don't have to pack as carefully. Con: You can't pack this as fully as a top-loading model, and zippers can fail.
　　Hybrid-Loader: The best of both worlds. Usually a top-loader with vertical side zippers.
　　Smart Features
　　 Look for packs that have features you need--and don't bother with the ones you don't. When everything's on your back, every ounce counts, and those special features can get heavy. Here's a list of some of the things you can look for.
　　
　　
　　Generously padded hipbelts (unlike the thin cloth waistbelts found on Sixties-era backpacks) represent a major advancement in pack design and greatly enhance your ability to carry tonnage into the backcountry.
　　
　　Most consist of various grades of foam: open-cell foam for cushioning, closed-cell or molded foam for firmness. The hipbelt should straddle your "iliac crest" - the 2 prominent bones on the front of your hips. This is the area where your pelvic girdle begins to flare out, providing the hipbelt with a stable, fortified foundation.
　　
　　 Some packs offer interchangeable belts, permitting a more customized fit, and even belts where the angle of the fit can be adjusted. The hipbelt's padded ends should not touch; you need some space to be able to cinch the belt securely. On the other hand, don't tighten a belt excessively. Your hips could be irritated if you do.
　　
　　 Internal-frame models include a lumbar pad. This large pad should offer cushioning yet should not feel spongy. If it does, it could break down quickly under a load.
　　
　　
　　Some internal packs place a thin but stiff sheet of plastic between you and the packbag. Often this is a material known as HDPE, or high-density polyethylene. This adds stiffness to the frame without adding much weight. Plus, it prevents objects in your pack from poking you in the back.
　　
　　Internals sometimes include some type of mesh or foam panel that rests near the middle of your back. This is an attempt to separate the pack from your back and encourage some air flow between the two. It offers modest help. Here is a trail-tested truth: Count on having a sweaty back if you tote an internal.
　　
　　
　　This involves the shoulder straps (padded and contoured), load-lifting straps, a sternum strap and belt-stabilizer straps. These items, and tips for adjusting them, are discussed in our clinic Fitting a Backpack. So-called ladder suspensions typically allow you to reposition the shoulder harness in 1-inch (or, preferably, smaller) increments. The more fine-tuning a pack permits, the better the fit.
　　
　　
　　Common materials are packcloth (a sturdy grade of nylon) and Cordura, a burly fabric with a brushed finished. Both resist abrasion and are coated for water resistance. Cordura is tougher and a bit heavier. Ballistics nylon, a strong, lightweight material, has popped up in newer pack designs and seems to work well. Internals usually offer an "extendable collar" or "spindrift collar" - additional nylon with a drawstring closure that allows the main compartment to stretch higher and hold extra gear.
　　
　　
　　Many internals allow you to detach the "floating lid" pocket from the pack and convert it into a fanny pack or daypack. That's a handy feature when you choose to make day hikes from a backcountry basecamp.
　　
　　Water-bottle holders/hydration pockets: Externals offer plenty of side pockets where you can stash a water bottle. Internals rarely do, although several now offer elasticized mesh "holsters" on the side where you can keep small bottles handy. Hydration systems (water reservoirs, or bladders, connected to a long sipping hose) have boomed in popularity. Many high-end packs now offer such systems.
　　
　　
　　Lash points allow you to attach even more gear to your pack if you feel the need. Climbers and early-season hikers should look for ice-axe loops, daisy chains (a series of small loops where you can dangle gear, such as carabiners) and crampon patches. A so-called shovel pocket holds items tight against the back of your pack; it's a good place to stash wet things. All of these extras, of course, add weight to a pack.