There are plenty of well designed backpacks out there with excellent padding and wide shoulder straps -- but many don't have sternum straps. Luckily, you can add one cheaply and get better support from your bag.
My Belkin business backpack is still serving me well after four years. However, when it was full, I found myself getting severe shoulder strain. This was because it's natural motion was to pull back on my shoulders rather than down on them.
If this sounds like your backpack, there's a solution: buy a third party sternum strap and add it yourself. These straps are an integral part of most camping backpacks, but unfortunately not for the packs you'd wear about town. There are a bunch of affordable options on Amazon.
Fitting the strap to your backpack can be done in a simple, three-step process:
- Depending on the straps you get, you may need to unfasten the shoulder straps on your backpack. If you've already got them at the perfect length, I recommend putting a stitch of coloured thread on your strap so you can save the sweet spot.
- Slot each sternum strap on to the respective shoulder strap and fasten your shoulder straps in place.
- Put on the backpack and fasten the sternum strap. Slide it up to the most comfortable level, and then adjust the tightness of the strap and tie it off.
This was the best modification I ever made to my business pack. The only annoyance is that the straps slide down to the bottom of the shoulder straps after the pack is taken off, so you'll have to pull them up every time you put it back on. However, compared to the back strain it used to cause me, this is no trouble at all.