Rating: 3 / 5
After loving my old Gregory Z-Pack, I had high hopes for the beautifully ventilated Z-55. As a southeastern hiker, I usually head west to high cool mountains when summer heat and humidity begin to batter Tennessee and the surrounding region. Thus, the airy backpanel of the Z-55 looked ideal for the 200+miles of Kentucky's Sheltowee Trace, which I hiked in late May and early June.
The pack's suspension proved to be finicky. The large bow in the back panel means I only achieved small areas of contact. Unfortunately, this resulted in undue pressure in the lower back (initially), followed my a downward sag, which resulted in increasing shoulder contact and fatigue.
Making the situation worse was the sternum strap. If it had held securely, it would have placed more support on my chest, which I far prefer to my shoulders. But the strap kept sliding upward until it eventually reached my throat, requiring me to stop and push the strap back down to my sternum.
However, the suspension was the only downside to the pack. There were thankfully a number of pluses to the Z-55. The hip belt pockets were a real blessing, a genuine improvement on the Z-Pack. All the access options (front pocket, stow-it pocket, and lid) remain, and they were very helpful.
The biggest plus was the vented back panel which WORKS. Despite a consistent heat index in the 90's and occasional 100's, I experienced a degree of ventilation and back comfort unlike any other pack I have tried. This ventilation comes at a heavy cost in less comfortable suspension, but may still be worth it if I venture out into very hot conditions in the future (so long as I am not on a long-distance hike, where day after day of shoulder and lower back discomfort became routine.)
With modification, this pack may recapture some of the great function of the Z-Pack (which I rated a 5/5 last year). But for now, the Z-55 is, for me at least, an unfortunate step back.