I really like my backpack (a Gossamer Gear Gorilla 40l). It has compression straps on the sides which are very useful to attach a tent or a sleeping pad. But when I use it on shorter adventures and tighten all the straps it becomes a hellish bundle of dangling webbing straps. Of course I can shorten all the straps and cut them to the minimal needed length. But I like the compression straps to attach things sometimes. And I need the shoulder straps to be a bit longer when I'm wearing an insulation jacket in winter.
Some backpacks have small pieces of velcro at the end of the straps to roll them up and fix them in place. But you always have to open the velcro, adjust the length and close them again.
I found a solution that is extremely easy and fast to implement (no sewing required). It works best if the ends of your straps are folded two times and thus have a small closed channel that you can use. If they don't come like this, it's very easy to sew them in that way.
Maybe this will help you to tidy up your backpack and ban the dangling mess forever.
Step 1: Materials
You only need some shock cord (elastic string), scissors and a lighter to tidy up the ends. And some very minimal knotting skills.
Step 2: Adding the Shock Cord
Cut a small piece of shock cord. Put one end of the shock cord through the loop/channel at the end of the strap. Guide the other end under the returning strap. It should be obvious when you look at the pictures.
Step 3: Making the Knot
Make an Overhand Knot (not that sure it's called that way but I'm pretty optimistic that a helpful sailor will soon correct me and point out the correct term) with both ends. Pinching the knot with your thumb and index finger and pulling with the other hand at the loose ends, try and bring the knot as close to the webbing as possible. Ideally the shock cord should stay under tension so the two webbing parts are always pulled together. When you're convinced that the knot is tight enough, shorten the loose ends and use the lighter to carefully burn the ends a bit to prevent them from fraying.
Repeat these steps for all the straps you want to roll up/shorten.
Step 4: How to Use
Now comes the easy part. When you want to compress the backpack, just grab the loop and pull. To shorten the strap, just roll it until it's short enough. Should you not like this solution you can easily cut the shock cord away without any harm done to your backpack.
I did the same to the shoulder straps, but I don't roll the straps since I adjust them quite often. I simply pull them down and they stay close to the load bearing straps without dangling around and annoying me.