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Contents: Selecting a Backpack | Using your backpack

Selecting a Backpack

Internal Frame Packs:
- The only choice for snowshoeing and ski trips, off-trail scrambling,
  because of less shifting and more control.
- Easier to stow in a car or airplane.
- Some now using tensioned mesh or channel to create a cooling air space

External frame packs:
- Cooler because of airflow between frame and your back.
- Great for hauling big, heavy and/or awkward loads.
- Allows you to carry big loads without leaning forward
- Cheaper.

Note: Almost everyone has an internal frame pack now. Occasionally you'll see an old timer like me with an external frame pack. I keep my old one in NJ. My internal frame pack is in Calif.

Ultralight packs favored by thru hikers are internal frame packs that weigh around 2 pounds. (Most internal frame packs are from 4 3/4 to 5 1/2 pounds.)

Features of internal frame packs:
Generally the more features the heavier the pack so there is a trade off.
  • Front panel access so you don't have to take everything out from the top to reach something at the bottom.
  • Multiple compartments (e.g.Sleeping bag compartment)
  • Adjustable suspension (shoulder harness adjustments [load-lifter or stabilizer], width adjustment for attachment point)
    Also hip-belt adjustments (compression straps, stabilizer straps, snuggers, trim straps, delta straps or load-lifter straps)
  • Ventilation system to keep your back dry (mesh or foam channels)
  • Lumbar pad to transfer loads to hips
  • External pockets
  • Pocket on waist belt
  • Hydration pack sleeve
  • Compression straps so load doesn't shift when pack is not full.
  • Gear loops (for snow shovel, crampon, sleeping pad, ...)
  • Attachment for skis and/or snowboard (e.g. straps at the top and pass-thru holes in side pocket or bottom loops)
  • Detachable day pack. Usually on travel packs.

Pack Bag Volume
Length of Trip External Frame
(in3 [cu in] and Liters)
Internal Frame
2-4 Days 1,500+ in3 (25+ Liters) 3,500-4,500 in3 (57+ L)
5-7 Days 2,000+ in3 (33+ Liters) 4,500-6,000 in3 (73+ L)
8-10 Days 3,000+ in3 (39+ Liters) 5,500+ in3 (90+ L)
Source: http://www.princeton.edu/~oa/ft/equipment.pdf

REI recommends 40 L (2,400 in3) to 70 L (4,200 in3) for overnight trips.
I've done overnights with a 1,200 in3 daypack, but had a lot of stuff hanging from the outside.
My old (late 60's) external frame (kelty style) pack is 2,600 in3 in two main compartments, and has worked for 5 day hikes.
Plus 650 in3 in 5 external pockets.

External frame packs can be smaller than internal frame packs because there are spaces outside the packbag to strap large items directly to the frame.

  • Under 2,000 in3: Small packs for day trips like hiking and ski touring. They have no frame, a thin belt, and possibly a chest strap, and vary in the number of pockets and other features.
  • 2,000 to 3,500 in3: Stream-lined packs for gear-intensive day trips like climbing and winter hiking. Most have a thin foam back pad, and straps to draw the pack against your hips (stabilizer straps) and upper back (load-lifters). The design is generally minimalist to reduce weight and bulk.
  • 3,500 to 4,500 in3: For light packers on warm-weather weekend trips. If your gear is bulky, get a pack closer to 4,500 in3ches for weekend trips.
  • 4,500 to 6,000 in3: Large enough for treks of up to a week, year-round. These popular packs vary greatly in design, features, and fit.
Source: Buying a Backpack: Fitting Solutions for Every Frame at AMC

The Complete Walker IV has a formula for computing the correct size which is available at Backpacking-guide.com
It makes a big difference if you go alone or with a group and how warm you sleep. For example: Spring or Fall 3 day trip, 150 lb hiker:
Cold sensitivity Number in group
Solo 2 3 ≥4
warm 2805 1870 1309 1122
normal 4208 2805 1964 1683
cold 5611 3741 2618 2244
winter trip
6734 4489 3142 2603
6 day trip
spring - normal
5952 3968 2777 2380
The Complete Walker formula doesn't distinguish between internal or external frame packs, but since internal frame is preferred now I would guess it assumes all gear will fit inside.

Torso Length:
According to Wayne Gregory, your correct frame size can be found by measuring your torso from the seventh vertebra down the spine to the point in the small of your back which is horizontally level with the top of your hip bones. To find this point, use your fingers to trace the hip bone upwards till you feel the point where the top edge of your hip bones curve inwards, on the side of the hip, creating something of a shelf. This measurement is the torso length, especially useful to consider those packs with non-adjustable back system. In fact this system that is used throughout the outdoor industry today to measure the exact body size and to determine the correct frame's size.

Sources: rootball at WhiteBlaze.net/forum/         Pack Fitting - Deuter
Measuring torso length at REI

Small - 16 - 18.5 in      Note: Some packs have several attachment points for the
Medium - 17.5 - 20.3 in         shoulder-straps and load lifters allowing you to adjust them.
Large - 19 - 22.5 in
Other adjustments:
Some (see Arc'tereyx link below) say you can bend the metal stays if there is a lot of space between your back and the pack frame when the pack is fully loaded.
I asked the manager of REI at Reno about this with my Gregory pack. He checked with the engineers at Gregory and they said leave them alone.

Arc'tereyx also allows you to adjust the angle of flare of your hip belt for the differences in mens and women's hip shape.

Backpacks: Finding Your Torso and Hip Size: Expert Advice from REI
Pack Fit Guide / Arc'teryx


Gregory     Arc'teryx   Deuter  Osprey   REI (These seem to be the most recommended)
Northface   Kelty       Lowe    Granite Gear
Reviews at OutdoorGearLab, Backpacker Magazine
 and BackpackGearTest.org - Packs
Top 5 Lightweight Backpacks For Thru-Hiking | Erik The Black's Backpacking Blog
The Nov. 2010 Backpacker gave the Gregory Baltoro 70 their editors choice hall of fame award.

Sierra Trading Post

Using your Backpack

How much weight to cary:
backpack weight distribution 15 - 25% of your body weight is a general rule.
On longer expeditions or winter trips this may go up to 1/3 of body weight.

How to Load a backpack:
The general rule is heaver items should be placed in the center and as close to your back as possible.
Usually higher up so with a slight forward bend you can center the load over your hips. The diagram to the right appears in many places, but it has more to due with the type of terrain than the pack type. For uneven steep or rocky trails you may want to put heavy items lower for stability.
I was getting in shape by tying heavy weights to the top of my external frame pack and when I made a slight slip on a rock in a stream crossing it pulled me in head first.
backpack weight distribution Usually the sleeping bag goes in the bottom compartment first along with whatever other small items you can fit around it. This acts as a foundation for the main compartment.
Weight should be balanced side to side to avoid the pack listing one way. See:
Gregory Packs - Trail Smart Packing System

There are two basic considerations in packing:
1. Weight distribution - See above diagram.
2. Ease of access. Items you may need in a hurry e.g. rain gear, water shoes for water crossings, should be toward the top, in front of the sleeping bag in the bottom compartment on the outside.
Your 10 essentials, and other items you may need in a hurry, sun screen, insect repellent, gloves, wind shirt, lunch, camera, headlamp, first aid kit, extra water, ... can go in the lid pocket or a side pocket for easy access.

Fuel canisters should go below food or in a side pocket.
When hiking in Harriman Park in NY we ran across some West Point cadets who had packs with several pockets in the front. Good idea, So I got some straps sewed on a small organizer which I can fasten to the front of my shoulder straps for things like my map, gps, notebook and camera.

Try to avoid attaching gear externally because it will swing, rattle, or snag plants on the trail.

When packing your backpack, be sure to fill in all empty space with small or compressible items. For example, you can stuff a shirt inside a pot, sox inside a cup, put a roll of duct tape around your hiking poles, or remove your sleeping bag from its sack and stuff it around other gear.
See How to Pack a Backpack | Wild Backpacker.
How To Pack A Lightweight Backpack | Erik The Black's Backpacking Blog

  • Loosen all suspension straps.
  • Position the middle of the hip belt over the hip bones and tighten. If the belt sits too high, it might constrict the stomach. If the position is too low, the fins might chafe.
    Over the hip bones is preferred, but some people wear it higher to avoid chaffing. Others put moleskin over the hip bones.
    Osprey has a heat mold system to custom fit your belt.
  • Tighten the stabilizer straps connecting the belt to the pack's bottom. It transfers the weight to the sides of the hips, allowing a more upright hiking position.
    You can adjust the stabilizer straps during your hike to relieve pressure points.
  • Tighten shoulder straps so 70 - 80% of the weight is on your hips.
  • Next, tighten the load-lifters. They should should angle back toward the pack body from a 30° - 60° angle.
    You may want to go back and adjust your shoulder straps again. As you tighten and loosen your shoulder straps it changes the angle of the load lifters so they have different effects. A higher angle means they have more effect on lifting the shoulder straps up. A lower angle means they do more to bring the pack closer to your back. It's a combination of the shoulder straps and load-lifters you need for comfort.
    There is some difference of opinion on their primary purpose. See load-lifters below.
  • Finally, tighten the chest strap. It can be minutely adjusted to relieve pressure on your shoulders
Some packs have several attachment points for the top or bottom of the shoulder straps and/or the load lifter straps. You may need to move these to match your torso size.

Load-lifters should angle back toward the pack body from a 30° - 60° angle.

There is some difference of opinion on the purpose of load lifters.
In my opinion they serve both purposes, transfer of weight and stabilization.

Transfer weight from shoulders:
Arc'teryx and others say, "The purpose of the load lifters is to slightly lift the shoulder straps from the shoulders, transferring more weight to the hips. There should be about a finger's width of space (a gap) between the top of your shoulders and the shoulder harness.
REI says "Gently snug the load-lifter straps to pull weight off your shoulders. (Over-tightening the load lifters will cause a gap to form between your shoulders and the shoulder straps.)"
Gregory says, "Tension the shoulder stabilizer straps until there is a loop in the top of the harness."

Stabilize the load:
Backpacker Magazine and Deuter say, "Snug the load lifter straps for a more stable load."
Tighten to pull the weight closer to your back for better control, and loosen them to allow the load to settle onto your hips for more comfortable striding.
The Complete Walker IV says, "When going uphill you tend to lean forward. So, slack off on the lift straps slightly to balance the load on your hips."
Backpacker Magazine says, " On long ascents, loosen the hipbelt and stabilizer straps to increase mobility for hips and legs. When going downhill, retighten."

Change adjustments thru the day to relieve pressure points on the shoulders.
You can adjust to load-lifter straps and sternum strap to shift pressure points from the shoulder straps.
Tighten the load-lifter straps to move pressure to the front of the shoulders and loosen to move pressure toward the top of the shoulders.
Loosen sternum strap to widen shoulder straps to minimize pain around neck.
Tighten to pull in and relieve pressure on arm pits.
You can make these adjustments back and forth during your hike.

Steep trail
Tighten straps for more control.

Lumbar strap on hip belt- Minimal effect.

More adjustment links:
Video at Backpacker Magazine
Internal Frame Pack Fitting | ALPS Mountaineering
Pack Fit Guide / Arc'teryx
How To Fit Your Backpack | Looking Glass Outfitters
Pack Fitting - Deuter Sport GmbH & Co. KG
Backpacker Magazine - Beginner Basics: Fitting A Backpack

Expert Advice from REI:
  How to Choose a Backpack
  Backpacks: Adjusting the Fit:
  How to Hoist a Loaded Backpack
Hiking Backpacks - Making The Right Choice at Backpacking-guide.com
Backpacks and Backpack Reviews - Trailspace.com
packs at outdoorsMalaysia.blogspot.com
Find the right pack at AMC
Buying a Backpack: Fitting Solutions for Every Frame at AMC
packs at OutdoorsMalaysia.blogspot.com
Panel Loader Backpacks for Hiking Photographers | Mountain Photographer : a journal by Jack Brauer
How to Adjust a Backpack | eHow.com
BackpackGearTest.org - Packs

last updated 7 Aug 2013