Almost every pack has them, those funky webbing straps that crisscross the sides. They're called compression straps, and their main purpose is to squish the load closer to the pack frame, bringing the weight and bulk nearer your back for better weight transfer and balance-in other words, more comfort. When cinched just right, compression straps help you avoid doing the boogie-woogie bumble while trotting down Mt. Lottasteps. Besides providing simple compression, side straps:
Control light loads that would otherwise flop about on short hikes from basecamp.
Tame weird cargo that the main sack can't manage. Items often lashed here include (but are hardly limited to) tent poles, sleeping pads, tripods, fishing rods, trekking poles, and dirty laundry.
Hold skis for those springtime jaunts to the snowline. To affix skis, slide the tails down through the straps with the edges facing the pack and lash the tips together. If the tails drop too low, they'll bump your calves going downhill; too high, and the skis will hang up on every low limb.
You probably won't buy a pack based on its compression straps, but you will come to either love or curse them. Look for these features:
Quick-release buckles, which speed attaching and removing things. When you must pitch a tent in a driving rain, it's no fun to wrestle the poles away from reluctant straps.
Straps long enough to secure something even when the pack is already bulging at the seams.
Straps that span the pack's side so they can squeeze a big pack small.
Appropriate placement of the lowest compression strap, which may cross the side water-bottle pocket. Some hikers like the security that affords, while others prefer quick, unfettered access to their bottles.
Even spacing up and down a pack-preferably three straps on each side-for consistent compression and load stabilization.
Webbing that doesn't stick or slip when sliding through the buckle.
Straps that don't block access to side pockets.
Easy entry into all zippered pockets without unbuckling or loosening the compression straps.
Heavy-duty stitching and reinforced anchors where the straps meet the pack so they can withstand abuse on
For really small loads, compress the straps before filling the pack. Otherwise, your goods will collect on the bottom when your goal is to distribute them evenly up and down your back.
If you're packing a full load, lash gear to the outside after the packbag is full so you don't compress the interior volume.
Don't lash self-inflating sleeping pads to the sides on thorny trails.
When bushwhacking, lash everything to the rear of the packnot the sidesunless you like to get stuck.
Crank the strap with an even motion; don't jerk, overtighten, or lift the pack by its compression straps.