after a lot of research I bought this
for mountain biking and love it. I considered the octane xct, but that had much less caring capacity for essentials.
I've got two tubes, pump, multitool, first aid kit, chain links, zip ties, light, and gels, and still have room for more. all of this is in the main compartment using the organizers. the accessible side pockets are unused but can carry my phone, keys, and more food bars easily.
the pack is super comfortable,I didn't even think about it or feel it on my 1.5 hour maiden voyage today. sits on my hips well, the shoulder pads just hold it up.
if you're thinking about this pack for trail and mountain riding, buy it!