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Fitting a Backpack

If you routinely experience back pain, shoulder pain, or hip pain when you carry a backpack, there’s a good chance that your backpack doesn’t fit you or that you’re not wearing it properly. This is surprisingly common among backpackers and kids returning to school.

The Biggest Mistakes that People Make

The number 1 reason why backpacks don’t fit is because people buy packs with the wrong torso size. Before you buy a pack, be sure to measure your torso size. Backpacks with adjustable torso lengths can somewhat relieve this problem, but they tend to be heavier.

The number 2 reason why backpacks don’t fit is because the hip belt is too big or too small (or you’re not using a pack with a hip belt: HUGE MISTAKE). Many manufacturers only make hipbelts in one size for their backpacks, and that size might not fit you. Come to terms with this and find a backpack that fits your waist, as it is today. Some manufacturers also offer replaceable hipbelts that can be switched out on backpacks, ensuring a perfect fit.

Don’t be tempted to buy a pack because it’s on sale, unless it fits your torso and hip size. Doing that is a mistake and you’ll suffer needlessly for it.

Here are a few things to check to make sure your pack is properly fitted:

Find Your Torso Length

To do so, you’ll need a friend and a flexible tape measure.

  • Have your friend locate the bony bump at the base of your neck, where the slope of your shoulder meets your neck. This is your 7th cervical (or C7) vertebra. Tilt your head forward to locate it more easily. This is the top of your torso length.
  • Place your hands on top of your hip bones (also known as your iliac crest), with fingers pointing forward, thumbs in back. This is the “shelf” on which your pack will rest. The middle of an imaginary line drawn between your thumbs is the bottom of your torso length.
  • Using the tape measure, your friend should measure the distance between the C7 and the imaginary line between your thumbs. Be sure you stand up straight when being measured. You now should have your torso length.

Use your torso length measurement to find your best pack size. Generally, manufacturers size their pack frames something like this:

  • Extra Small: Fits torsos up to 15 ½”
  • Small: Fits torsos 16″ to 17½”
  • Medium/Regular: Fits torsos 18″ to 19½”
  • Large/Tall: Fits torsos 20″ and up
Hip Belt
  1. Does the hip belt cover your hip bones (illiac crest) or has it slid below them?
  2. If you can’t tighten your hip belt enough and it keeps falling below your hips, it may be too long.
  3. If your hip belt rests on your lower back and not the sides of your hips, it may be too short.
  4. Is your hip belt snug, but not so tight that it causes back pain?
  5. If you loosen your shoulder straps completely, can you feel the pack resting on your hips?
  6. Drop your arms so they hang along your sides. If your hip belts pocket are behind your arms, your hip belt is probably too short.
Torso Length
  1. Do you know the length of your torso and does it match the torso size of your backpack?
  2. If there is space between the tops of your shoulders and your shoulder straps, your pack’s torso length is too long. If your pack is adjustable, make the torso length shorter. Otherwise, return your backpack and get one with a shorter torso length.
  3. Carrying all of the weight of your pack on your shoulders shows that your pack’s torso length is too short. If your pack is adjustable, make the torso length longer, so most of the weight rests on your hip belt. Otherwise, return your backpack and get one with a longer torso length.
Shoulder Straps
  1. If the front of your shoulder get very sore when your backpack, make sure that most of the weight is on your hips and not your shoulders. If the cause of the pain is because your pack is too heavy, get a new pack with wider or more padded shoulder straps, or lighten your load.
  2. If the shoulder straps on your pack rub against your neck, loosen the sternum strap. If this doesn’t work, your pack may have a harness that is too narrow for you and you should exchange it.
Sternum Strap
  1. If you can feel your sternum strap on your neck, try lowering it. It is too high. If that still doesn’t work, try getting a pack with a larger torso size.
  2. If tightening the sternum strap doesn’t keep the shoulder pads on your shoulders, you probably need a backpack with a narrower shoulder harness.
Load Lifters

If your backpack doesn’t come with load lifters, don’t panic. They are often provided on higher volume packs where you need to carry heavy loads, but not on smaller volume or ultralight backpacks.

  1. If your backpack has load lifters and the back of your head hits the top of your pack, try loosening the load lifters.
  2. Loosen your load lifters if there is a gap between the tops of your shoulders and your load lifters.
  3. If you can feel your pack pulling you backwards, tighten them. This will narrow the gap between your back and the pack and tilt the pack forward, so more of the load is carried by your hips. Also make sure that the heaviest items in your pack, such as water, are located as close to your back or sides as possible and not in the back of your pack.
Try on Lots of Backpacks

Buying a backpack should never be an impulse decision. Try on lots of different packs and test them fully loaded on a long day hike before you commit to keep them. Come to grips with the fact that some packs will never fit you because you are too tall, too short, too round, too skinny, or you have no hips. Backpacks are just like business suits (men’s and women’s): some fit and some don’t.

Manufacturer and retailer return policies are also flexible enough these days, that you can try lots of backpacks before committing to one, guilt free. Backpack makers want you to enjoy your backpack and tell your friends how much you love it. Buying a backpack is one of the most important decisions you can make if you like hiking, so take your time in making a decision.

A Few more thoughts….

There are a lot of reasoning and philosophies about what fits with backpacks. Pehaps the strongest point made is “Try on Lots of Backpacks.” If still in doubt, choose the tallest size between two  comfortable packs…it will put more of the load on your hips/legs directly, bypassing the spine and shoulders.

Different people will also advocate different framed packs. No frame, internal frame and external frames. All fit a bit differently. Raw measurements do not take this into account. The shape of a frame and harness system can also influence fit. Straight frames are never fully comfortable. Curved frame sheets tend to hug your back better, with less additional weight in padding. Stiff, tubular frames can restrict hip movement while hiking, important for comfort while walking.

Width of a backpack makes a big difference. Tall and narrow, vs, short and wide. Often these are chosen for a more specific purpose. Narrow packs seem to be better for climbing, and bushwhacking. Wider packs (and more compact loadings) can be better on flatter, open trails. You should pay attention to the size of the pockets (if any) and how vulnerable they are to snagging. I find narrow 11″-12″ pack-body width comfortable. Wider 13″-14″ pack-bodies can catch on all sorts of things on narrow trails.

The overall use of load lifters is a rather controversial subject. Like belt stabilizers, they are designed for keeping the loaded pack near your center of gravity.  There is no such thing as a magical “load” lifter. Putting them at 45 degrees “above” your shoulders, or straight across your shoulders, or at 70 degrees above your shoulders doesn’t do anything for carrying the loads. They DO help manage any “overload,” though. Keeping the weight close to your body will reduce any “pulling back” with the loaded pack.

Compression straps can help by keeping a load more stable and “rattle” free. Also, they help keep the center of gravity closer to your body. They also keep the pack stiff and nearly self supporting, resulting in a better carry, generally.

Center of gravity seems to be in two major places with packs. The first is the overall COG mistake will force you to lean forward to balance a load while walking. This will  happen when the  load is high on  your back. The second COG mistake is forcing the pack to pivot on the wast belt. This will put stress on your shoulder harness. The two combined, can be quite uncomfortable. This has more to do with loading, than fit( other than not using your waist belt correctly)

The packs COG, load lifters, torso strap, and shoulder straps can all combine to put a lot of stress on your chest. Women pick up early on this with any pressure on the breasts becoming quite uncomfortable. These all conspire to reduce breathing. In high exertion activities, such as hiking or climbing, this is bad. You should NEVER feel like the pack is restricting your breathing. Often this is just a matter of adjustment, Keep the heaviest items low in your pack. This will move the packs COG closer to the waist belt and reduce the need for loading on the shoulder straps. The next heaviest items should be loaded close to your back and as low as possible. Ready items (lunch, sweaters, jackets) should be placed on top.

If your tent is the heaviest single item, where should it be? In the pack and on the bottom of course. Or, get a lighter tent, so you can put it next up, in the pack, ready to be used in wet weather. If you have trouble with pack collapse, try rolling it tightly and placing it upright, next to your back. There are tricks you can play with gear to help the pack be more comfortable. But there is no fix for an ill-fitting pack. If you do not have the correct size pack, then all the tricks in the world will not make the pack fit better. I would avoid the weighted bags at REI or EMS when checking the load balance of a pack. These are usually very dense pushing the weight and COG very low.

You would do better to simply take all your gear, and load it to get a good idea of how the pack will carry. They will not usually complain, but tell them you are looking to buy a new pack. Often they will help.

Sources: Section Hiker, Patagonia


Jennifer Penrose

Penrose Physical Therapy

"Leading Experts Helping People Become More Active and Mobile, Reduce Stress and Achieve Longevity… So They Can Enjoy Great Health For Years to Come!"

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