The Nucleon is a neat design, neither so tall it crashes into the back of your helmet, nor so wide it grabs passing branches. Its 20L space is simple: a cavernous main pocket with a small internal zipped pouch, and a medium-sized outer zipped pocket with no compartments.
We’ve run it as a hydration system – a 3L Widepac bladder is sold separately for £20 (US$29) and other bladders fit the generous compartment that’s held away from your back with comfy padding and a mesh cover. As a daypack without the hydration system (there are bottle pockets) it swallows even more kit.
Wide shoulder straps are matched by a removable waist strap bearing semi-mesh hip pockets. At 750g it’s big but tough. Its showerproof-ness has faded but there’s barely a bramble scratch on it; part of the chest strap clip has snapped but still works, and the zips remain as smooth and secure as it was on the first day.