limit twisting of the shoulder strap 150 under tension from lace 140 reinforcement panel 176 can be made from any suitable material for example but not limited to polypropylene polyethylene or composite materials in certain embodiments reinforcement panel 176 can include one or more cutouts 177 for example a cutout 177 for adjustment device 130 and a cutout 177 so that lace 140 can pass through reinforcement panel 176 in certain embodiments reinforcement panel 176 can include a groove or channel similar to channel 172 in fig5 for example between cutouts 177 so that lace 140 can be disposed within the channel as also shown in fig1 and separately in fig1 in certain embodiments back panel 110 can include frame 190 in certain embodiments frame 190 can be disposed inside of back panel 110 so that it is not visible from the exterior of backpack 100 frame 190 can provide additional structure to back panel 110 in order to facilitate forming a smooth curve frame 190 can help distribute force imparted to back panel 110 when spacing panel 120 is placed under tension by tightening the lace 140 frame 190 can be made from any suitable material for example but not limited to polypropylene polyethylene other plastics or composite materials in certain embodiments frame 190 can be a solid flexible board for example in the shape of back panel 110 extending from upper edge 115 to lower edge 117 and across the width of back panel 110 in certain embodiments for example as shown.