Avalon Tyro recurve Backpack review

The NEW Tyro recurve Backpack from Avalon, is slimline, lightweight, but packed full of features.
Large zip storage compartment, to place your recurve riser and limbs inside, arrow tube included. On the inside of the front flap there are 3 mesh storage pockets for your smaller accessories, secured with a velcro fastening.
Adjustable padded straps for comfortable transportation.

[@CheMysteryLabs]

I have this backpack, and I'm having trouble adjusting the length of the arrow tube for 800 spine arrows (30"). I was previously using 28" 1100 spine arrows. The strap seems too short to extend the tube any further. Any help would be awesome :)