Ergon BD-2 /// $165
Put some ergonomically obsessed German engineers to the task of designing a mountain bike pack and this is what you get.
The BD-2 is the middle child of Ergon's three-bag family, all of which use a ball-and-socket swivel a rigid plastic frame and a waist harness for support. In short: You can tighten the snot out of the waist strap and literally cut the shoulder straps off the pack and it won't fall off.
In practice, putting the pack on and off took some getting used to. When it's on and snugged tight, it feels like a supportive weightlifting belt, and the actual heft of the pack has a way of disappearing.
The pack's eight (count 'em, eight) pockets sound like organizational bliss, but the BD-2's 915 cubic inches of cargo space is just begging for better layout. A fleece-lined pocket for glasses or electronics is conspicuously lacking, and aside from the main hold, the individual "pockets" range from barely big enough for a multi-tool to accommodation for two tubes, tops.
The bag funnels most of its contents into a gaping main compartment, space that is protected by the hard plastic external frame and cushioned on the bottom by the rain-fly stowed underneath. That plastic frame saved my ass once, literally, when I went down on the road after blowing a bead off a tire. And the few times I needed to use the rain-fly it worked like a charm. But if water is coming from inside the pack, say, from a leaky bladder or as condensation from a cold one, then everything in that main compartment is getting wet.
Aside from its so-so layout, the pack revealed two near-fatal flaws. First, it took a few well-placed zip ties to keep the hip pads tied into the plastic frame. The second problem was the swiveling movement of the pack ratcheted loose the nyloc locknut holding the ball-joint together. Ergon says the problem has been addressed and new packs come with longer bolts and a retention clip.
Despite all this grousing, I like this pack. The concept is sound, and after a $2 trip to the hardware store its execution is there, too. Still, it's pricey, and it comes without a bladder, but if you've got a troublesome neck or back it's worth looking at.