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Some backpacks have shoulder straps that are connected near the top with a bridge as shown in the pictures below.

I tend to find backpacks with this strap configuration to be the least comfortable and was curious as to why they exist. Maybe I'm not wearing them properly.

Do straps like these have any advantages compared to straps that aren't bridged together?

backpack bridge strap example 1 backpack bridge strap example 2 backpack bridge strap example 3

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(Comment because I'm just hypothesizing, but it's way too long for a comment.)

I strongly suspect this is a matter of trying to build it cheap. I just went through the house examining all the packs I own and I find I have exactly one bridged pack here. (One pack is in another city, I can't examine it.)

Some notable differences between it and the various other packs I own: It is the cheapest pack. It is the only pack with no internal structure to it. It is a checkpoint-friendly laptop bag--it is not the sort of thing you're likely to lug around for an extended period. Everything else I have here is meant for being carried for hours at a time.

Note how the straps in all your pictures are diverging as they leave the pack. Pretend there's no bridge--note that in the simple case this produces a force at an angle to the attachment point and thus will apply a shear force to the connection point. Note that the bridges in all your pictures will transfer this shear force across to the other strap where it will be countered by the load from that side--the force connecting the straps to the pack itself will be straight.

There are other ways of accomplishing this but the bridge is the simplest, cheapest, and lightest approach. Also, with a pack with an internal structure the straps start from higher up but when there is no internal structure there is nothing to enforce a separation between the attachment points and thus they inherently will be lower on your body--making a bridge less of a detriment. (I have also observed an awful lot of people who carry such packs leave the straps too loose, causing it to ride lower and the make the bridge less of an issue.)

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  • It might also be newer and/or narrower cheap packs. My commuting bag is old and cheap, and doesn't have one (Karrimor Skye25, black/grey pack here) while my much newer hydration pack sort of does (blue straps at the same link), in that the straps come from one piece of fabric above the body of the pack. The cost of manufacture may be less if a single piece can be attached in one step, more than offsetting the extra fabric and offcut
    – Chris H
    May 25 at 8:08
  • @ChrisH My laptop bag is the oldest one I own, I do not believe this is a recent thing. And I wasn't thinking so much of attaching in one step as a matter of how strong that attachment must be and what must be done to keep it from bowing the pack. May 26 at 2:40
  • Fair enough on the age (though some of my kit is so old your oldest could be far newer). I liked your point about the strength, having seen the stitching stressed at the inside top of separate straps, but thought the manufacturing aspect could be additional, or at least offset the extra cost
    – Chris H
    May 26 at 6:13
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It helps transfer weight away from the shoulders to the back. It also helps balancing the weight by bridging an off-balanced load to the other side.

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  • Is there a proper way of having the pack or bridge sit on your back or shoulders? I can't really figure out a good position with a heavy pack. The bridge tends to dig into my shoulders and/or limit my movement when reaching for something or looking up. Jul 2 at 1:55
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    Try lowering the backpack so it sit's as close to your hip as possible. The bridge transfers the weight to your back when you lean forward. It is not meant to transfer weight to your back when you are erect. In the standing position, the bridge functions solely to aide in balancing the load. With a heavy load, you should have a waist belt. If the backpack is constricting your movements at the shoulder, your back pack does not fit properly or has not been adjusted properly. youtube.com/watch?v=xsVJwVKfg-k
    – Bookaholic
    Jul 2 at 21:49

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