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Reviews > Packs > Internal and External Framed Backpacks > Gregory Z45 > Test Report by Shane Williams

Gregory z45 Technical Pack
Test Series by Shane Williams
Initial Report: July 15th, 2011
Field Report: October 25th, 2011
Long Term Report: January 3rd, 2012

Initial Report

Tester Information:

Name: Shane Williams
Email: sherpa[dot]colorado[at]
Age: 37
Location: Colorado Springs, Colorado USA
Gender: Male
Height: 6' 0" (1.83 m)
Weight: 170 lb (77 kg)


As a child I lived in the last house on a dead end street. Just beyond my house was a wilderness area. I started hiking and exploring there, and I've never stopped. I started backpacking in the South Eastern Appalachian Mountains, including portions of the Appalachian Trail. Today I primarily hike in the Colorado Rockies. My pack weight is approximately 30 lbs (13.61 kg) to 50 lbs (22.68 kg). I often carrying more gear than necessary hoping that I wonít need it. I enjoy weekend excursions into the High Country with friends and lower elevation day trips with my family.

Product Information:

Manufacturer: Gregory Mountain Products
Year of Manufacture: 2011
Manufacturer's Website:
MSRP: $189.95 US
Reported Weight: 4.062 lb (1.85 kg)
Measured Weight: 4 lb (1.81 kg)
Tested Size: Large
Capacity: 50 L (3051 cu in)
Max Load: 40 lb (18.14 kg)
(Photo courtesy of

Product Features:

  • JetStreamô LTS Suspension with 3 waistbelt size adjustment options
  • Ventilated and moisture wicking harness and waistbelt
  • Side zipper access that goes the length of the pack
  • Large stretch mesh front pocket
  • Dual hydration ports and sleeve
  • Removable top lid
  • Side, bottom and top compression
  • Dual quick access waistbelt pockets
  • Exterior side pockets with pass-through compression
  • Single axe/tool attachment points with secure carry under compression flaps
  • Water-resistant zippers
  • 7001-T6 hollow aluminum stay
  • 210D double diamond ripstop and 210D x 420D HD flat weave fabrics


Torso Sizes: Small: 16 to 18 inches (40.64 - 45.72 cm) Medium: 18 to 20 inches (45.72 - 51 cm) Large: 20 to 22 inches (51 - 56 cm)
Waist Sizes: Small: 22 to 28 inches (56 - 71 cm) Medium: 28 to 34 inches (71 - 86 cm) Large: 34 to 56 inches (86 - 142 cm)

Product Overview:

The Gregory z45 is a mid-weight technical pack consisting of 7 storage compartments and an internal hydration pouch. Equipped with Gregoryís proprietary ďJetStreamĒ LTS (Load Transfer Suspension) system and a 7001-T6 hollow HDPE aluminum framesheet, it certainly isnít lacking in comfort or features. The auto-fit shoulder harness is a contoured, moisture wicking and reinforced with a hybrid sewn/bound pad. Similarly the waistbelt is also comprised of the same sewn/bound padding on the internal surface. The waistbelt also has a fixed dual density lumbar pad to transfer weight from the pack to the hips. A top loading access point provides main entry into the large center compartment. A side access zipper spanning the majority of the pack provides an alternative approach to pack access. Two hydration ports are positioned on the upper right and left to allow unobstructed access for hydration hoses. The z45 has a load rating of 40lbs (19 kg).

Construction and Design

When reading the specifications for this pack, itís easy to become overwhelmed in the specification details, especially where it concerns the fabrics. The following is a brief technical overview of the two fabrics that make up the majority of the fabric used in the construction of the z45.


210D double diamond is a denier polymer fabric that derives its name from the linear mass density of the fibers. In the ď210Ē portion the name denotes the mass in grams per 9000 meters. The ďDĒ portion of the 210D naming convention specifies the unit of measurement in Denier. A single Denier equates to 1 gram per 9000 meters. Double diamond rip-stop is the type of weave given to this fabric that helps to isolate tears should the fabric become compromised. The majority of this pack is constructed with the 210D fabric.

210D Double Diamond Fabric

410D follows the same nomenclature as stated above. The numeric portion of the name indicates that the weight for this fabric is 200 grams heavier than the 210D fabric mentioned above. This fabric is used along the bottom (gray) portion of this pack, as well as the underside of the top lid and the internal hydration pouch. Gregory has selected the 410D fabric for these areas intentionally. For the bottom of the pack the heavier fabric will provide additional strength to the pack. This area is particularly susceptible to abrasion when setting the pack down on the ground with a heavy load or sitting while wearing the pack. The underside of the pack lid has been selected to provide additional water resistance to the top loading access port, which helps to keep the pack contents dry. Likewise, the internal hydration pouch is comprised of this heavier fabric to help contain any moisture produced from a hydration bladder.

210D Double Diamond (blue) and 410D (gray) Fabrics


JetStreamLTS (Load Transfer Suspension)

Gregory has designed a proprietary load suspension system, JetStream LTS, that aims to properly transfer and balance the weight from the pack to the hips and shoulders. LTS is an acronym for ďLoad Transfer SuspensionĒ and is a series of features that contribute to this technology. These features are the dual density foam lumbar pad, the Thermo-formed die cast HDPE (High Density Polyethylene) framesheet, the hollow 7001-T6 aluminum stay, the hybrid sewn/bound auto-adjusting shoulder harness, and upper foam placed between the top of the shoulder blades.

The Lumbar pad, as the name indicates, is positioned at the base of the back along the lumbar portion of the spine. This is a dual density foam pad thatís made of the same moisture wicking perforated foam material as the interior of the waistbelt. This dual pad has a thickness of 1.25 in (3.17 cm) and seems to have a beaded gel substance internally that molds easily when pressure is applied. This pad provides lower back support but also assists in keeping the pack balanced and in place.

Between the lumbar pad and the upper shoulder blade pad is a mesh section that houses the thermo-formed die cast HDPE framesheet and 7001-T6 aluminum stay. These two elements work together to provide a lightweight support system to absorb the weight of the pack. A unique feature of these items is that is has a slightly convex curvature. This creates a space between the back and the pack which is designed for ventilation and air to flow. This removes unnecessary points of contact on the back, which is the ďJetStreamĒ feature.

The hybrid sewn/bound shoulder harness is also made of moisture wicking perforated mesh and foam. This material has been selected for the shoulder harness to help reduce hot spots caused by excessive rubbing. These straps are contoured to fit over the shoulders and come together at the sternum strap. The exterior portion of the straps have gear loops for clipping items such as watches or holding a hydration hose in place.

The upper foam pad positioned between the shoulder blades is a thinner version of the lumbar pad and provides the upper contact point making the zero point of contact ventilated airflow possible. This is also made of the same perforated mesh moisture wicking foam.

JetStream LTS System


The z45 is a mid-weight 50 Liter (3051 cubic inch) technical pack. Equipped with dual compression straps along the left and right sides as well as the bottom rear, it can be customized to fit a variety of loads. The top lid has extendable straps that can be used to increase the capacity to accommodate loads that may be slightly larger than the main compartment. The lid itself also serves as a zippered compartment that includes an internally fixed clip for securing car keys or a small clip pouch.

The center front of the pack also has a large stretch mesh pocket with a compression strap and clip that attaches to a permanently fixed anchor at the top of the pack. This is large enough to hold a wind shell, light weight jacket, or poncho that can be accessed quickly. In addition to this large center pocket, the lower right and left flank have two pockets of the same material. These pockets are a perfect fit for water bottles and have their own compression straps that can be used to compress and extend as needed.

The waist belt has two large raised pockets constructed of mesh and 210D fabric. The dimensions for these pockets are 5 in (12.70 cm) wide by 4 in (10.16 cm) high and have a depth of 2.25 in (5.72 cm). This size pocket can easily hold a couple of energy bars, GPS unit or cell phone.

The main pack compartment has 2 access points, the largest being the top loading opening covered by the lid, the second is a 15 in (38.10 cm) vertical zip opening. This compartment provides the majority of the packs storage volume. The interior section of the main compartments houses the hydration pouch.

The Contents Unpacked
The Contents Packed

Initial Impression:

Upon receiving the Gregory z45 Technical pack, I found it to be in excellent condition and free from rips, tears, or stains. Right away I could tell that I was going to like this pack. When I first tried it on it didnít have the weight to load the pack, but it had a nice feel. When the pack was fully weighted, the JetStream LTS system certainly gave it a different feel from any pack that Iíve ever worn. The lumbar pad keeps the waist belt from slipping. This coupled with the HDPE framesheet and 7001-T6 aluminum stay gave the pack a very solid feel. I intentionally tried to sway the pack to see how it would respond if I were to be pitched to one side or another and it didnít slip or shift.

I did find a couple of features that were a little concerning. I was surprised to find that the internal hydration pouch doesnít have a way to hang a hydration bladder. This seems like it would cause the bladder to become bunched and bind the hose. Another feature that was a little surprising was the bottom compression straps. These seem fairly short for a pack this size. I typically roll a foldable camp chair around my small backpacking tent and use the lower compression straps to affix them to my pack. These compression straps were too short to allow for this configuration, which Iíve accomplished with smaller packs. I was still able to carry the tent and chair, but moved the tent to the upper portion of the pack.

All in all Iím really excited about testing the z45 pack. It has a superb fit and feel, a nice set of features, and a versatile size. I look forward to seeing how it performs in the field.


- Just the right size to be a small overnight pack or large day pack.
- Removable lid for expansion.
- JetStreamLTS System.
- Vertical zipper entry.


- Doesnít have a hang device for a hydration bladder.
- Small underside compression straps.

This concludes my initial report. Come back in September to see how the z45 Technical pack performed in the field. A special thanks to and Gregory Mountain Products for the opportunity to be a part of this test series.

Field Report: October 24th, 2011

Field Conditions:

During the past two months of testing Iíve utilized the Gregory z45 pack on 1 overnight backpacking trip and 4 day hikes. These trips have ranged from casual strolls to steep arduous ascents. During my overnight camping trip I visited the Sangre De Cristo Mountain Range in Southern Colorado. The round trip distance was 14 miles (22.54 km) and an elevation gain of 6250 ft (1905 m). The overall weather conditions couldnít have been better. Temperatures ranged from the 45 F (25.00 C) to 83 F (46.11 C). This hike was broken up into two days to maximize the changes of summiting these two peaks on the second day. Day 1 consisted of 2850 ft (869 m) in elevation gain over 5 miles to an alpine lake where we camped for the evening. I had a fully loaded pack weighing around 50 lb (22.68 kg). Day 2 was comprised of 3400 ft (1036 m) in elevation gain over the remaining 2 miles (3.22 km). After spending a while on the summit we returned via the same route, gathered our overnight gear at camp then descended back to the trail head for a total distance of 9 miles (14.49 km). Pack weight on day 2 was around 25 lbs (11.34 kg) for the ascent. The remaining hikes in this series consisted ranged from 2 m (3.22 km) to 6 m (9.66 km). Conditions were mostly sunny and pretty with the exception of a hike up the Manitou Incline at the base of Pikes Peak, where a fair amount of the hiking was done before dawn.

Field Report:

First and foremost I have to say that this pack rides like a Cadillac. During the trip to Challenger and Kit Carson peaks I really pushed the weight limits with this pack. The large model is rated for 40 lb (18.14 kg) and I had upwards of 50 lb (22.68 kg). Even with the extra weight the pack rode well and felt very stable, even while negotiating streams and loose rocky terrain. I think there were several factors that played into the comfort and stability of this pack. The lumbar pad does an excellent job of keeping the pack from sliding off the hips. The LTS Jet Stream system works well at bringing stability to the pack and providing ventilation to the center of the back. The contoured shoulder straps bring stability to the upper portions of the pack by allowing the weight to rest more towards the center of the chest rather than the outsides of the shoulders. The waist belt keeps the lower portion of the pack solidly anchored. I also really like the double adjustable belt clip and deep dual pockets affixed to the front of the waist belt. These are handy and have great storage capacity for accessory pockets.

During my Initial Report I had some concerns about the lack of hanger for a hydration bladder. While the z45 does have an internal hydration sleeve it doesnít provide a way for the bladder to be suspended so it simply rests within the sleeve. I thought that this would cause the bladder to bind, making it difficult to draw water. This wasnít an issue, but I did encounter other issues with the placement of the hydration system. When I arrived at the campsite at the end of Day 1 of my overnight excursion of Challenger/Kit Carson, I hung my pack on a branch. When I came back 30 minutes later I noticed a large wet area on the ground, upon closer inspection I realized that the pressure within the pack was pressing on the bladder, causing it to push water out the bite valve. Fortunately, there was a nearby stream to refill the bladder. This was the only time during the test period that this type of thing happened, which leads me to wonder if exceeding the recommended maximum load capacity contributed to this issue. This is something that I plan on experimenting with during the next portion of testing.

Item Placement:

One of the interesting things about hiking with a new pack is figuring out how and where to store the various gear needed. The following is a breakdown of my item placements. Iíve found this to be the best placement for my gear to keep a fully loaded pack properly weighted and balanced. Hopefully it will give some indication to the placement and storage capacity.

Waist-Belt Pockets:

These have been wonderful to have and are nicely placed. I typically carry a compass and altimeter in my left pocket and usually energy bars and gels in the right pocket. Iíve also used the right pocket as a temporary location to house my head lamp just after dawn. It usually rides there until I stop and remove my pack, then I move it to the Lid Pocket.

Side Panel Pockets:

These pockets are nice and will hold water bottles of just about any size. Iíve also used them to carry fuel bottles for my stove, foldable map case, and folded tent poles. When the tent poles are placed in this pocket they to stick out of the top, but the compressions straps higher on the pack can be strapped around them to keep them in place.

Rear Center Pocket:

This pocket usually holds my keys clipped into the anchored latch clip, toilet paper, ski goggles, sun glasses, warm hat, sun screen, knife, and additional hydration lids and accessories.

Lid Pocket:

This pocket usually holds my keys clipped into the anchored latch clip, toilet paper, ski goggles or sun glasses, warm hat, sun screen, knife, additional hydration lids and accessories.

Center (Main) Compartment:

Pretty much everything else goes in this center compartment. From bottom to top I usually pack sleeping bag, extra clothes, cook ware and stove, poncho, food and water.


One of the nice features of the removable lid pocket is that the lid has fully adjustable front and back straps. This came in handy when looking for a place to carry my tent. I extended the straps out, placed the tent between the top of the pack and the underside of the lid pocket, then I cinched it down until it was snug enough to keep the tent in place. It never slipped or caused any problems while carried in this configuration. This can be seen in the above picture as demonstrated in my initial report. The remaining exterior straps were also used similar fashion as represented in the aforementioned photo.

Field Image: Kit Carson Summit


Iíve thoroughly enjoyed wearing the Gregory z45 pack. The contoured shoulder straps, lower lumbar pad and LTS Jetstream design make this pack a real pleasure to wear. Even when fully loaded it has a comfortable, stable, stream lined fit. Further testing with the hydration system is needed to determine if overloading of the pack caused leakage, or if it was due to the lack of a bladder hang device. All in all this is an outstanding pack.


  • Lumbar Pad
  • Contoured Shoulder Straps
  • Well-designed pocket placements


  • Issue with bladder leakage.

This concludes my Field Report. Please come back in December for my follow-up Long Term Report. A special thanks to and Gregory Mountain Products for the opportunity to be part of this test series.

Long Term Report: January 3rd, 2012

Field Conditions:

During this final series of testing Iíve continued to utilize the Gregory Z-45 pack on one overnight trip and 2 day hikes in the Rocky Mountains of Colorado. The most significant trip was an overnight outing where I ascended the Colorado 14ers Mount Belford and Mount Oxford, located in the Sawatch Mountains of Central Colorado. Above 13,000 ft (3900 m) temperatures dropped to 18 F (-7 C) and wind speeds increased to a sustained 30 MPH (48). This yielded a wind-chill between -5 F (-20 C) and 5(-15 C). Duration above 13,000 ft (3900 m) was 5 hours and total trip duration was 13 hours. The remaining hikes around Colorado Springs and in the Pikes Peak National Forest around Woodland Park. These outings were all casual hikes ranging from 2 to 4 hours. Conditions were sunny with temperatures between 40 F (4 C) and 70 F (21 C).

Field Report:

There are certain types of gear, such as backpacks and boots, that take a fair amount of use before they really start to reveal their sweet spot. While Iíve been impressed with the z45 features and functionality in previous reports, itís only been during this past series in which this pack has begun to feel like ďhomeĒ. During my Field Report I was still working to find the right gear placement that would yield a properly weighted and balanced pack. During the ascent of Mount Belford and Mount Oxford I found that balance and this pack felt as if it were custom made. The pack had a weight of 40 lbs (18 kg) and even after a fatiguing 13 hour day, it remained comfortable. The combination of contoured shoulder straps, lumbar pad, and LTS Jet Stream system makes this pack feel snug, streamlined and balanced.

In my Field Report I mentioned that I had issues with the hydration system placement that caused pressure to be applied to the bladder and caused leaking. I didnít have any further issues with the hydration system and concluded that the leakage was due to overweighting the pack. I didnít have any other issues with the hydration system leaking or any problems with the placement causing binding. Iím still slightly disappointed that the pack doesnít have a way to clip the bladder to the top of the pack so that it hangs rather than sits in the hydration pouch. That being said, the current design is perfectly functional, so this can be regarded as personal preference.

As Iíve tested the z45 there are a couple of features that were unassuming at first, but as Iíve used the pack they have redefined what I would hope for in a pack. One is the expandable lid that accommodates variable sized payloads. Not only that, but it can also be used similarly to a compression fixture that provides an additional method for carrying bulk items such as a tent. When there are wet items such as a wet exterior shell or rain fly the lid can be compressed down over these items as they are draped over the pack which allows them to dry out while in route to the next destination. Second is the vertical zipper access along the left side of the pack. At elevation during winter conditions itís all too easy to lose heat when stopping which make adjustments or get a quick bite to eat. The vertical zipper has been especially useful by providing a quick alternate method to accessing much needed gear.

Field Image: Mount Belford


As Iíve continued to wear the Gregory Z-45 pack itís quickly become my favorite pack. Itís held up nicely and hasnít prematurely shown signs of wear or suffered broken latches or buckles. Itís also obvious that a lot of thought went into the architectural design as well as material selection. The thing that I love the most about this pack is the fit and feel provided by the contoured shoulder straps, LTS Jet Stream system and the lumbar pad. The only thing I would change about this pack would be the provision of a bladder hanger. Other than that, this is an excellent pack that has redefined the features that I consider luxury.

This concludes my Long Term Report. A special thanks to and Gregory Mountain Products for the opportunity to be a part of this test series.

Read more reviews of Gregory gear
Read more gear reviews by Shane Williams

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