Verging on pannier territory, this backpack attaches to a seatpost-mounted alloy rack. The unusual thing is the position of the pack when fitted to the rack: upright, rather than prone.
The pack itself had ample space for our test load while the padded laptop sleeve takes a 15in machine snugly. The 600 denier fabric is durable and will take a dousing of rain, though it isn’t fully waterproof.
Fixing to the rack takes seconds, as does removal, and accidental removal is near impossible. It’s reasonably comfortable to wear on your back, though not as good as others with more flexibility.
The rack is a bit weighty, given some of the light seatpost options we’ve tested.